Del Mar Photonics - Newsletter Fall 2010 - Newsletter Winter 2010
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Photonics West 2011: Presentations on Terahertz Wave Technology and Applications
Course: Terahertz Wave Technology and Applications
Date: Wednesday, 26 January 2011
Time: 8:30 AM 12:30 PM
Instructor(s): Xi-Cheng Zhang, Rensselaer Polytechnic Institute (United States)
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A pulsed terahertz (THz) wave with a frequency range from 0.1 THz to 10 THz is
called a "T-ray." T-rays occupy a large portion of the electromagnetic spectrum
between the infrared and microwave bands. However, compared to the relatively
well-developed science and technology in the microwave, optical, and x-ray
frequencies for defense and commercial applications, basic research, new
initiatives and advanced technology developments in the THz band are very
limited and remain unexplored. However, just as one can use visible light to
create a photograph, radio waves to transmit music and speech, microwave
radiation (MRI) or X-rays to reveal broken bones, T-ray can be used to create
images or communicate information. This course will provide the fundamentals of
free-space THz optoelectronics. We will cover the basic concepts of generation,
detection, propagation, and applications of the T-rays, and how the up-to-date
research results apply to industry. The free-space T-ray optoelectronic
detection system, which uses photoconductive antennas or electro-optic crystals,
provides diffraction-limited spatial resolution, femtosecond temporal
resolution, DC-THz spectral bandwidth and mV/cm field sensitivity. Examples of
homeland security and defense related projects will be highlighted.
THz patterned antennas for THz-TDS
Paper 7937-13 of Conference 7937
Date: Sunday, 23 January 2011
Time: 3:00 PM 3:15 PM
Author(s): Pouya Maraghechi, Abdulhakem Y. Elezzabi, Univ. of Alberta (Canada)
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We report on a comprehensive investigation of radiation characteristic of THz
emitters using structures with specific patterns. Such unique geometrical
properties in these antennas result in improving the coupling radiation to the
free space. It is shown that these novel antennas produce higher radiation power
when compared to the bow-tie antenna and their un-complementary structures. It
was found that the complimentary structure having the highest structure
complexity gave the best radiation power compared to all other antennas. To the
best of our knowledge this is the first time that complimentary antennas have
been used as emitters for generating THz radiation.
Terahertz holographic interferometry
Paper 7957-42 of Conference 7957
Date: Wednesday, 26 January 2011
Time: 6:00 PM
Author(s): Andrei A. Gorodetsky, Victor G. Bespalov, Saint-Petersburg State
Univ. of Information Technologies, Mechanics and Optics (Russian Federation)
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We present our new modeling and research results on terahertz holographic
interferometry, a technique allowing to reconstruct changes in inner dielectric
object structure. The technique is somehow alike the corresponding one in
optics, but allows managing optically opaque objects. Using the broadband pulse
THz radiation with a spectrum in the range of 0.1-2.5 THz we can reconstruct
object deformations up to several microns in the bulk 3d object.
Stimulated Smith-Purcell semiconductor THz sources
Paper 7953-28 of Conference 7953
Date: Tuesday, 25 January 2011
Time: 4:30 PM 4:50 PM
Author(s): Don D. Smith, Texas A&M Univ. (United States)
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A simple three-layer planar semiconductor device consisting of a Gunn drift
region, a dielectric layer and a metallic grating generates stimulated
Smith-Purcell radiation. Frequency is determined solely by the ratio of domain
velocity to grating period. The radiation is monochromatic, coherent, and
strongly polarized along the axis of the device. Simulations of the device agree
well with analytic calculations. InP yields radiated power density of 30nW per
micron of device width at 0.27 THz. A hypothetical InN device yields 3.5uW/um at
0.25THz and 21nW/um at 1THz. The device is simple to fabricate, operates at room
temperature, and warrants experimental investigation.
Terahertz antiresonant reflecting hollow-core waveguides for sensing
applications
Paper 7938-18 of Conference 7938
Date: Thursday, 27 January 2011
Time: 4:40 PM 5:00 PM
Author(s): Borwen You, Ja-Yu Lu, National Cheng Kung Univ. (Taiwan); Chi-Yu
Chan, Chin-Ping Yu, National Sun Yat-Sen Univ. (Taiwan); Hao-Zai Chen, National
Cheng Kung Univ. (Taiwan); Tze-An Liu, Jin-Long Peng, Industrial Technology
Research Institute (Taiwan)
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A dielectric hollow tube utilized as a terahertz antiresonant reflecting
hollow-core waveguide (THz-ARRHW) sensor has been demonstrated to detect the
minute variation of both refractive index and thickness in macromolecule layers
deposited on the tube wall, and to identify liquid vapors from the various core
indices. The minimum detectable variations of sample-quantity and concentration
are down to 1.2picomole/mm^2 and 0.2%, corresponding to the variation of
2.9ตm-thickness and 0.001-refractive-index, respectively. A THz-ARRHW sensor is
also used to identify various volatile liquid vapors in the hollow-core based on
different induced core indices, and the detectable vapor density is down to
0.0001g/cm^3.
Recent progress of THz generation and detection in ambient air or gases
Paper 7917-15 of Conference 7917
Date: Tuesday, 25 January 2011
Time: 1:30 PM 2:00 PM
Author(s): Xiaofei Lu, Benjamin W. Clough, I-Chen Ho, Jingle Liu, Jianming Dai,
Xi-Cheng Zhang, Rensselaer Polytechnic Institute (United States)
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THz time domain spectroscopy has been largely applied on the measurement of
semiconductor, electro-optic crystals, and selected chemical, biological and
explosive materials. Here we will highlight THz gas photonics and its
applications, with an emphasis on spectroscopic capabilities. The most recent
results of using air (and selected gases) as the emitter and sensor material for
both generation and detection of broadband THz waves will also be reported. Air,
especially ionized air (plasma), has been used to generate intense peak THz
waves (THz field > 1.5 MV/cm) with a broadband spectrum (10% bandwidth from 0.1
THz to 46 THz).
Integrated Terahertz pulse generation and amplification in quantum cascade
lasers
Paper 7945-11 of Conference 7945
Date: Sunday, 23 January 2011
Time: 11:20 AM 11:40 AM
Author(s): Sukhdeep S. Dhillon, Simon Sawallich, Nathan Jukam, Dimitri Oustinov,
Julien Madeo, Rakchanok Rungsawang, Ecole Normale Supérieure (France); Stefano
Barbieri, Pascal G. Filloux, Carlo Sirtori, Univ. Paris 7-Denis Diderot
(France); Xavier Marcadet, Alcatel-Thales III-V Lab. (France); Jerome Tignon,
Ecole Normale Supérieure (France)
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We demonstrate an integrated approach to generate and amplify Terahertz (THz)
pulses within a quantum cascade laser (QCL). Using an ultrafast interband
excitation of a THz QCL, THz pulses are generated via charge carrier
acceleration within the QCL miniband. The generated pulses are subsequently
amplified at the QCL gain as they propagate through the laser cavity. As well as
integrating the generation and amplification of THz pulses, this technique can
potentially permit efficient THz pulse injection into sub-wavelength double
metal resonators.
Length dependence of forward and backward THz DFG in a strongly absorptive
material
Paper 7917-17 of Conference 7917
Date: Tuesday, 25 January 2011
Time: 2:20 PM 2:40 PM
Author(s): Yen-Chieh Huang, Yen-Hou Lin, Yen-Yin Lin, National Tsing Hua Univ.
(Taiwan)
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Owing to the vast difference in wavelengths for THz difference frequency
generation (DFG), a nonlinear optical material is often transparent to optical
waves but could be highly absorptive to the THz wave. It has been widely
believed that, in such a strongly absorptive nonlinear optical material, the
useful DFG length is on the order of the THz absorption length. We show in DFG
theory and experiment that the THz wave can grow monotonically over cm distance,
despite an absorption length of 50 microns at 1.5 THz in lithium niobate.
Encoding terahertz signatures into laser-induced plasma acoustic waves
Paper 7938-3 of Conference 7938
Date: Thursday, 27 January 2011
Time: 8:50 AM 9:10 AM
Author(s): Benjamin W. Clough, Jingle Liu, Xi-Cheng Zhang, Rensselaer
Polytechnic Institute (United States)
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The enhancement of acoustic waves, from audible into the ultrasonic range, is a
linear function of the THz intensity incident on a laser-induced plasma, making
THz-enhanced acoustics (TEA) useful for THz detection. By using a dual-color
laser field to produce the plasma detector, THz spectroscopic information can be
encoded into the acoustic emission, making it possible to obtain the electric
field profile of the THz pulse by simply "listening" to the plasma at a
distance.
Semiconductor plasmons for THz frequency plasmonics
Paper 7937-12 of Conference 7937
Date: Sunday, 23 January 2011
Time: 2:35 PM 3:00 PM
Author(s): Euan Hendry, The Univ. of Exeter (United Kingdom)
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Surface plasmons (SPs) are electromagnetic waves that propagate along the
interface between a conductor and insulator. To date, studies of SPs have been
limited to optical frequencies near metallic plasma frequencies, where SP modes
are strongly confined to metal surfaces. However, we have shown that certain
semiconductors can support confined SPs at THz frequencies. We have demonstrated
that SPs play an important role in a variety of physical phenomena, elucidating
their role in the transmission of THz radiation through semiconductor structures
such as sub-wavelength slits and holes.
Coherent control of ultrafast photocurrents in GaAs
Paper 7937-30 of Conference 7937
Date: Monday, 24 January 2011
Time: 1:55 PM 2:20 PM
Author(s): Sangam Chatterjee, Kapil K. Kohli, Jan Mertens, Philipps-Univ.
Marburg (Germany); Mark Bieler, Physikalisch-Technische Bundesanstalt (Germany)
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The relationship between the electrical field of an optical pulse and its
encompassing pulse envelope is characterized by the carrier-envelope phase
(CEP). We show, that by using a phase stable pulse pair generated in a pulse
shaper we can use the relative CEP between the two pulses as a new degree of
freedom in coherent control experiments even for pulses that are not in the
single-cycle regime. We demonstrate how to use the CEP to coherently control the
shift current generation process in bulk GaAs, by measuring the emitted THz
radiation in a standard THz emission setup. A straightforward theoretical model
corroborates our experiment.
Using the gene expression profile of jurkat cells to determine whether terahertz
(THz) radiation couples to DNA and impacts transcription processes
Paper 7897-13 of Conference 7897
Date: Monday, 24 January 2011
Time: 2:20 PM 2:40 PM
Author(s): Jessica E. Grundt, Benjamin D. Rivest, Caleb C. Roth, Bennett L.
Ibey, Michael L. Doroski, Jason A. Payne, William P. Roach, Gerald J. Wilmink,
Air Force Research Lab. (United States)
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Theoretical models suggest that 2.52 THz radiation couples directly to DNA and
affects transcriptional processes; however, this phenomenon has not been
empirically confirmed. In this study, we hypothesized that if THz radiation does
damage DNA then exposed cells will express known damage and repair genes. To
test this hypothesis, we irradiated Jurkat cells using a THz laser (2.52 THz,
252 mWcm-2, t=5-50 minutes), and evaluated their response using viability, qPCR,
and microarray techniques. We found several genes were markedly upregulated in
each THz exposure group; however, the majority encoded for heat shock proteins
and few for DNA repair proteins.
One- and two-dimensional THz spectroscopy on semiconductor nanostructures
Paper 7937-32 of Conference 7937
Date: Monday, 24 January 2011
Time: 2:45 PM 3:10 PM
Author(s): Michael Woerner, Max-Born-Institut für Nichtlineare Optik und
Kurzzeitspektroskopie (Germany)
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Using our novel high field terahertz source we performed various nonlinear
experiments on semiconductor nanostructures. In one-dimensional nonlinear
propagation experiments on n-type GaAs we observed ballistic high-field
transport and THz-induced interband tunneling of electrons. Two-dimensional THz
correlation spectroscopy performed on intersubband transitions of two coupled
quantum wells shows distinct polaronic features of the intersubband transitions.
Using nanoscale molecular dynamics modeling and Raman spectroscopy to
investigate the direct effect of Terahertz radiation on double-stranded DNA
Paper 7897-15 of Conference 7897
Date: Monday, 24 January 2011
Time: 3:00 PM 3:20 PM
Author(s): Gerald J. Wilmink, Jessica E. Grundt, Air Force Research Lab. (United
States); Brett R. Boyce, U.S. Air Force Academy (United States); James E. Parker
III, Air Force Research Lab. (United States) and The Univ. of Texas at San
Antonio (United States); Brady Mcmicken, The Univ. of Texas at San Antonio
(United States); Caleb C. Roth, Bennett L. Ibey, Michael L. Doroski, Benjamin A.
Rockwell, Robert J. Thomas, William P. Roach, Air Force Research Lab. (United
States)
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Theoretical models suggest that 2.52 Terahertz (THz) radiation can couple
directly to the natural breathing modes of double stranded DNA (dsDNA) resulting
in the creation of "bubbles" between dsDNA. In this study, we used Raman
spectroscopy and nanoscale molecular dynamics modeling (NAMD) tools to evaluate
the effect that 2.52 THz radiation has on the hydrogen bonding in dsDNA. Raman
spectra were collected as various wavelengths (414 nm, 514 nm) on both salmon
sperm dsDNA (~2-3k base pairs) and custom-designed dsDNA (polyA/T, 50bps).
Comparable analyses were also conducted for hyperthermic and UV
positive-controls.
Monolithically integrated THz transceivers
Paper 7953-27 of Conference 7953
Date: Tuesday, 25 January 2011
Time: 4:00 PM 4:30 PM
Author(s): Michael C. Wanke, Mark Lee, Christopher D. Nordquist, Michael J.
Cich, Sandia National Labs. (United States); Albert D. Grine, LMATA Government
Services (United States); Chuck T. Fuller, John L. Reno, Sandia National Labs.
(United States)
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We demonstrate a monolithically integrated THz transceiver consisting of a
Schottky diode embedded into a THz QCL waveguide. Besides functioning as a
heterodyne receiver for externally incident radiation, the device is a useful
tool for characterizing the performance and dynamics of the QCL. This talk gives
an overview of the device, demonstrates receiver operation, and presents laser
dynamics measurements especially related to feedback of the QCL's emission due
to retroreflections. Sandia is a multiprogram laboratory operated by Sandia
Corporation, a Lockheed Martin Company, for the United States Department of
Energy's National Nuclear Security Administration under contract
DE-AC04-94AL85000.
Ultra-sensitive, room-temperature THz detection based on parametric upconversion
by using a pulsed 1550nm optical source
Paper 7917-36 of Conference 7917
Date: Wednesday, 26 January 2011
Time: 4:00 PM 4:30 PM
Author(s): Mohammad J. Khan, Jerry C. Chen, Zong-Long Liau, Sumanth Kaushik, MIT
Lincoln Lab. (United States)
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The paper will detail ultra-sensitive room temperature detection of THz
radiation using nonlinear up-conversion. We will describe the experimental
setup, focusing on the architecture and performance of the pulsed 1550 nm
optical pump, the nature of THz sources that are employed, the quasi
phase-matched GaAs crystal and its fabrication process. Temporal and spectral
scans showing the up-converted light generated from continuous-wave and pulsed
THz sources, using bulk and phase-matched GaAs crystals and different optical
detectors, will be presented. Measurements of the noise equivalent power, the
phase-matching bandwidth, and temporal resolution of the THz detector will be
compared with theoretical calculations.
Optical properties and applications of liquid crystals in the THz frequency
range
Paper 7955-25 of Conference 7955
Date: Wednesday, 26 January 2011
Time: 4:30 PM 5:00 PM
Author(s): Ci-Ling Pan, National Tsing Hua Univ. (Taiwan)
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In the past decade, THz studies ranging from investigations of ultrafast
dynamics in materials to medical, environmental sensing and imaging have been
actively explored. For these and future applications in THz communication and
surveillance, quasi-optic components such as phase shifters are indispensable.
The birefringence of liquid crystal (LC) is well known and extensively utilized
for the manipulation of optical radiation in the visible and near-infrared
range. Recently, there have been increasing interests in the study of
liquid-crystal-based devices for application in the sub-millimeter wave or THz
frequency range. In this paper, we review recent available optical constants of
selected liquid crystals in this important frequency range and recent advances
in liquid crystal THz optic and photonic devices.
1/f noise in Schottky diodes
Paper 7939-64 of Conference 7939
Date: Wednesday, 26 January 2011
Time: 6:00 PM
Author(s): Peter H. Handel, Univ. of Missouri-St. Louis (United States); Hadis
Morkoç, Virginia Commonwealth Univ. (United States)
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MBE-grown ErAs:InAlGaAs metal-semiconductor Schottky diodes are best suited for
use in focal plane arrays for millimeter and sub-millimeter wavelength imaging.
The present paper applies the quantum theory of 1/f noise to individual diodes
of this type, to back-to-back ErAs contacted diodes without sidewalls, and also
to similar diodes fabricated with sidewalls. We start from the quantum 1/f
expression of the spectral density S_I(f)= 2 e I_d +(e^3 alpha_H I_0/3 k_T
f)[v_r v_d/(v_r+v_d)][2N_d(V_dif-V)/e Epsilon]^1/2. This expression takes into
account the image force and is valid both in the diffusion-limited (v_r>>v_d)
and thermionic-limited (v_d>>v_r) limiting regimes. Here V_dif-V is the Schottky
barrier height, Mu the mobility, N_d the concentration of donors, e the
elementary charge, alpha_H the Hooge constant, and Epsilon the permittivity of
the semiconductor. For a small, heavily doped semiconductor, our conventional
collisional quantum 1/f expression of alpha_H is
alpha_H=(4alpha/3Pi)(6kT/m*c^2)=10^-9 Tm/(4m*100K), with v_r=(kT/2Pi m*)^1/2,
v_d=Mu[2e N_d(V_dif-V)/Epsilon]^1/2. For larger semiconductor contacts a
coherent quantum 1/f contribution may yield a much larger alpha_H. Here alpha is
the fine structure constant 1/137, m the electron's mass and m* its effective
mass. Quantum 1/f noise is a property of physical cross sections, a new aspect
of quantum mechanics.
THz and millimeter wave vacuum electronic sources
Paper 7938-14 of Conference 7938
Date: Thursday, 27 January 2011
Time: 2:50 PM 3:10 PM
Author(s): Laurence P. Sadwick, InnoSys, Inc. (United States)
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We will present recent work on a new class of vacuum electronic devices designed
for high power operation in the millimeter wave (mm-wave) to low THz frequency
region. These vacuum electronic devices are built using microfabrication and
micromachining techniques. Power levels ranging from watts to milliwatts can be
produced in a reproducible fashion. Some potential applications of these mm-wave
and THz sources will also be presented.
Modelling of detector cavities at THz frequencies
Paper 7938-17 of Conference 7938
Date: Thursday, 27 January 2011
Time: 4:20 PM 4:40 PM
Author(s): Stephen D. Doherty, National Univ. of Ireland, Maynooth (Ireland)
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Work being carried out at NUI-Maynooth is considering a mode matching approach
to the simulation of closed cavities. This approach is based operates by
cascading the S-matrices across, and conserving power, at each junction. This
talk will examine various approaches to simulating closed cavities and will
focus primarily on this method. An outline of how the introduction of additional
reflection matrices can be employed to model a closed cavity structure will be
presented. The introduction of an absorption matrix, determined by the
dielectric properties of the material in question, to determine the optical
performance of a cavity enclosed absorber will also be examined.
Ultrafast gain switching of quantum cascade lasers
Paper 7937-24 of Conference 7937
Date: Monday, 24 January 2011
Time: 10:35 AM 11:00 AM
Author(s): Sukhdeep S. Dhillon, Nathan Jukam, Dimitri Oustinov, Rakchanok
Rungsawang, Julien Madeo, Ecole Normale Supérieure (France); Stefano Barbieri,
Christophe Manquest, Carlo Sirtori, Univ. Paris 7-Denis Diderot (France); Suraj
P. Khanna, Edmund H. Linfield, Giles Davies, Univ. of Leeds (United Kingdom);
Jerome Tignon, Ecole Normale Supérieure (France)
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Terahertz (THz) time domain spectroscopy is now a widely used technique where it
is essential to know both the amplitude and phase of a THz wave. Nonetheless,
THz amplifiers, capable of increasing the THz wave field, are presently lacking.
In this context THz quantum cascade lasers (QCL) are very promising devices for
amplification. Gain clamping in these devices, however, limits the attainable
amplification. Here we circumvent gain clamping by coupling a THz QCL and an
integrated Auston-switch to perform ultrafast gain switching. The resulting
non-equilibrium gain is not clamped above laser threshold and large
amplification of input terahertz pulses is demonstrated.
Controlling THz plasmons with the electron spin state
Paper 7937-11 of Conference 7937
Date: Sunday, 23 January 2011
Time: 2:20 PM 2:35 PM
Author(s): Cameron J. E. Straatsma, Abdulhakem Y. Elezzabi, Univ. of Alberta
(Canada)
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We investigate the effects of photonic magnetoresistance on the propagation of
terahertz (THz) radiation in multilayered metallic media. These subwavelength
plasmonic structures contain alternating layers of ferromagnetic and
non-magnetic metal thin films, which allow for control over the electron spin
state. In particular, using THz time-domain spectroscopy, a photonic analogous
giant magnetoresistance effect is observed and its application in actively
controlling THz plasmons is studied. We demonstrate the possibility of
implementing this effect to produce active THz guided wave devices.
Ultrafast carrier capture and THz resonances in InGaAs quantum posts
Paper 7937-2 of Conference 7937
Date: Sunday, 23 January 2011
Time: 9:10 AM 9:35 AM
Author(s): Dominik Stehr, Univ. of California, Santa Barbara (United States) and
Forschungszentrum Dresden-Rossendorf e.V. (Germany); Christopher M. Morris,
Univ. of California, Santa Barbara (United States); Diyar Talbalyev, Los Alamos
National Lab. (United States); Martin Wagner, Forschungszentrum
Dresden-Rossendorf e.V. (Germany); Hyochul Kim, Univ. of California, Santa
Barbara (United States); Antoinette J. Taylor, Los Alamos National Lab. (United
States); Harald Schneider, Forschungszentrum Dresden-Rossendorf e.V. (Germany);
Pierre M. Petroff, Mark S. Sherwin, Univ. of California, Santa Barbara (United
States)
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Semiconductor quantum posts - nanowire-like InGaAs heterostructures in a GaAs
matrix - were investigated with respect to their carrier capture dynamics after
photoexcitation into the GaAs matrix. The results of the THz experiment
demonstrate that after ultrafast excitation, electrons relax within a few
picoseconds into the quantum posts, which act as efficient traps. Saturation of
the quantum post states, probed by time-resolved photoluminescence, was reached
at approximately ten times the quantum post density. Additionally, possible
electronic THz resonances with a dipole moment in the growth direction were
probed showing a broad response around 1.5 THz.
Intersubband impact ionization in THz QWIPs: shaping band structure
reorganizations to design novel detectors
Paper 7945-33 of Conference 7945
Date: Monday, 24 January 2011
Time: 8:40 AM 9:00 AM
Author(s): A. Delga, Univ. Paris 7-Denis Diderot (France); F.-R. Jasnot, Ecole
Normale Supérieure (France); Amandine Buffaz, Univ. Paris 7-Denis Diderot
(France); H. Guo, National Research Council Canada (Canada); Laetitia
Doyennette, Univ. Paris 7-Denis Diderot (France); Louis-Anne de Vaulchier, Ecole
Normale Supérieure (France); Zbigniew R. Wasilewski, Hui Chun Liu, National
Research Council Canada (Canada); Vincent Berger, Univ. Paris 7-Denis Diderot
(France)
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In this paper phase transitions and instabilities in Thz QWIPs will be studied.
At low temperature, a current phase transition occurs when the voltage reaches a
threshold where a quantum well can be depleted by efficient impact ionization.
This depletion induces an enhancement of the local electric field and results in
a barrier breakdown at the contact, which dramatically increases the current
injection in the device. Hysteresis is observed between these two states of the
system. It is crucial to understand the physics of the electronic transport in
this device in order to be able to design very sensitive Thz detectors, working
at the edge of the phase transition. In this paper, we describe in detail the
electronic transport, and show how a full calculation of the transport
(including the calculation of impact ionization and electronic capture in the
wells) leads to the full I(V) curve, despite its very sophisticated shape.
Thanks to this modeling, the design of very efficient Thz detectors will be
discussed.
Phonon and polaron enhanced IR-THz photodetectors
Paper 7945-34 of Conference 7945
Date: Monday, 24 January 2011
Time: 9:00 AM 9:20 AM
Author(s): Hui Chun Liu, Chun-Ying Song, Zbigniew R. Wasilewski, Margaret
Buchanan, National Research Council Canada (Canada)
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We investigate the active use of phonons and polarons for realizing new
optoelectronics devices. We present an application of the concept to
photodetection in the infrared-terahertz spectrum. The ability to design a
phonon or polaron is the first step in making use of them. We show this by a
model system employing the electron intersubband excitation in quantum wells
coupled with phonon modes. This results in a photodetector with a high response
at the selected wavelength.
GaN for THz sources
Paper 7945-35 of Conference 7945
Date: Monday, 24 January 2011
Time: 9:20 AM 9:40 AM
Author(s): Michel Marso, Univ. du Luxembourg (Luxembourg)
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In this work we investigate the unique electrical and thermal performance of GaN
to improve two different approaches to generate THz radiation. One method is the
heterodyne photomixing, where the THz output power is restricted by the thermal
and electrical limits of the conventionally used LT GaAs. The aim of our work is
to increase the output power by replacing the LT GaAs with low-temperature grown
GaN. In the second approach GaN-based ultrafast high electron mobility
transistors are developed for use in a high power high frequency oscillator
circuit that acts as source for a frequency multiplier chain.
THz techniques for human skin measurement
Paper 7897-12 of Conference 7897
Date: Monday, 24 January 2011
Time: 2:00 PM 2:20 PM
Author(s): Yu Guan, Takayuki Shibuya, Koji Suizu, Nagoya Univ. (Japan);
Shin'ichiro Hayashi, RIKEN (Japan); Kodo Kawase, Nagoya Univ. (Japan) and RIKEN
(Japan)
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We are developing several novel THz techniques for skin measurement. A
high-resolution tomographic imaging was demonstrated using a reflection-type
terahertz time-domain spectroscopy. The wideband spectrum of the terahertz waves
provided high-axial resolution of 5?m leading to tomographic imaging of
multilayered skin structure. Secondly, we have demonstrated a sensitive THz
imaging method using an interference effect. We applied this technique for the
thickness measurement of human skin adhered onto a sticky tape. Thirdly,
metal-mesh film can be used for sensing when samples adhere to the metal
surface. We report on the spectrum change of metal-mesh with horny layer.
Multi-THz fields exceeding 100 MV/cm: an ultrabroadband source for sub-cycle
nonlinear optics
Paper 7917-11 of Conference 7917
Date: Tuesday, 25 January 2011
Time: 10:30 AM 11:00 AM
Author(s): Alexander Sell, Friederike Junginger, Olaf Schubert, Bernhard Mayer,
Univ. Konstanz (Germany); Tobias Kampfrath, Martin Wolf, Fritz-Haber-Institut
der Max-Planck-Gesellschaft (Germany); Daniele Brida, Marco Marangoni, Giulio
Cerullo, Politecnico di Milano (Italy); Alfred Leitenstorfer, Rupert Huber,
Univ. Konstanz (Germany)
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We present a table-top source of extremely intense multi-THz transients covering
the spectral regime between 0.1 and 140 THz. Electric field amplitudes of up to
108 MV/cm and pulse durations as short as a single cycle are demonstrated with
our hybrid Er:fiber-Ti:sapphire laser system. All THz waveforms are
electro-optically detected. The multi-branch fiber laser generates gate pulses
as short as 4.3 fs. Our high-field THz facility opens the door to extremely
nonlinear optics in a previously hard-to-access spectral regime. First
applications include THz coherent control and four-wave mixing studies as well
as all-magnetic control of coherent spin waves.
Broadband emission from THz quantum cascade lasers
Paper 7953-24 of Conference 7953
Date: Tuesday, 25 January 2011
Time: 2:00 PM 2:20 PM
Author(s): Dana Turcinkova, Giacomo Scalari, Maria Amanti, Mattias Beck, Jerome
Faist, ETH Zurich (Switzerland)
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We demonstrate broadband laser emission at THz frequencies from quantum cascade
laser structures based on heterogenous cascades. The active material is composed
by five stacks of three different active regions. Each active region is based on
a 4-quantum well structure employing a bound-to-continuum transition. Laser
emission is observed over a bandwidth of nearly one THz, spanning from 2.24 THz
to 3.2 THz. Peak powers of more than 2 mW from a double metal waveguide and
maximum operating temperatures of 100 K have been observed with threshold
current densities as low as 230 A/cm^2 at 10 K.
Advancements in photomixing and photoconductive switching for THz spectroscopy
and imaging
Paper 7938-1 of Conference 7938
Date: Thursday, 27 January 2011
Time: 8:00 AM 8:30 AM
Author(s): Elliott R. Brown, Wright State Univ. (United States) and Physical
Domains, LLC (United States)
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Ultrafast photoconductive devices have been an important breakthrough in THz
technology during the past two decades. Photoconductive switches have become the
workhorse in moderate-resolution time-domain systems, and photomixers have been
widely implemented in high-resolution spectrometers of various types. The
primary photoconductive material has been low-temperature-grown GaAs. More
recently, this has been rivaled by ErAs-GaAs: a nanocomposite consisting of ErAs
nanoparticles embedded in a GaAs matrix. ErAs-GaAs photomixers have produced
very useful THz output power levels between 1.0 and 10.0 microwatt when pumped
by low-cost DFB lasers operating around 780 nm. ErAs-GaAs photoconductive
switches have produced average output power approaching 1 mW, and peak power
exceeding 1 W when pumped by frequency-doubled fiber model-locked lasers. The
photomixer performance has been utilized in the first U.S. commercial THz
photomixing spectrometer which has already been demonstrated on a variety of
interesting materials including polar vapors, solid explosives, polysaccharides,
nucleic acids, and nonlinear-optical crystals. The photoconductive switch
performance has been utilized in a THz impulse radar having a broadband power
spectrum centered at around 500 GHz, and a relatively simple gated-receiver to
provide pulse averaging and noise reduction. The impulse radar has been used for
several applications in biomedical imaging, such as imaging of skin burns, skin
cancer, and the ocular cornea.
Semiconductor-coated deep subwavelength spoof surface plasmonic waveguide for
THz and MIR applications
Paper 7938-8 of Conference 7938
Date: Thursday, 27 January 2011
Time: 11:20 AM 11:40 AM
Author(s): Ruoxi Yang, Wangshi Zhao, Zhaolin Lu, Rochester Institute of
Technology (United States)
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We propose integrated waveguides for terahertz (THz) and mid-infrared (MIR)
applications on wafer platform. Based on the prototype of spoof plasmonic
waveguides consisting of textured metallic surface, we explore the possibility
of coating periodic metallic pattern with silicon (at 0.6 THz) or germanium (at
MIR region of 30 THz) to further shrink the relative mode size of propagation
spoof plasmonic waves. Numerical modeling via 3D finite-difference time-domain
(FDTD) has shown deep sub-wavelength mode confinement in transverse directions
to smaller than ?/50 by ?/50, with an estimated propagation loss of less than
0.1 dB for each repetitive unit.
THz lasing concepts based upon InAs/GaSb broken-gap heterostructures
Paper 7938-10 of Conference 7938
Date: Thursday, 27 January 2011
Time: 1:20 PM 1:50 PM
Author(s): Dwight L. Woolard, U.S. Army Research Office (United States); Weidong
Zhang, North Carolina State Univ. (United States)
No abstract available Add to My Schedule
THz thermal emission from a 1D photonic crystal
Paper 7938-12 of Conference 7938
Date: Thursday, 27 January 2011
Time: 2:10 PM 2:30 PM
Author(s): Ian A. Zimmerman, Ziran Wu, Hao Xin, Richard W. Ziolkowski, The Univ.
of Arizona (United States)
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We have experimentally and theoretically investigated a simple 1D, bi-layered
electromagnetic crystal structure composed of air and silicon slabs. We have
calculated the emissivity using Kirchhoff's thermal radiation law, as well as by
calculating the density of states directly, and have compared those results to
the experimental values. Our ultimate goal is to be able to control the spectral
emission of an electromagnetic crystal in the THz region (or other wavelength
ranges, such as the infrared) by engineering its band structure with the desire
to develop a cheap, incoherent broadband THz source.
Electromagnetic crystal (EMXT) based THz components
Paper 7938-16 of Conference 7938
Date: Thursday, 27 January 2011
Time: 4:00 PM 4:20 PM
Author(s): Ziran Wu, Wei-Ren Ng, Michael E. Gehm, Hao Xin, The Univ. of Arizona
(United States)
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All-dielectric Terahertz waveguides based on hollow-core EMXT fiber are
fabricated via THz rapid prototyping using polymer jetting technique. Several
waveguides of identical cross-section and differing lengths are characterized by
THz time-domain spectroscopy (THz-TDS) to extract the waveguide intrinsic
propagation loss. Measurement results agree very well with simulation. This as
an initial example demonstrates a waveguide with low propagation loss of 0.03
dB/mm at 105 GHz. Based on the waveguide, an EMXT antenna is also formed by
modifying the defect shape into a horn. Simulation shows good performance of
this horn antenna. The antenna is fabricated by the same rapid prototyping
method, and its far-field pattern measurement result will be reported.
Nonlinear holographic imaging of terahertz radiation
Paper 7917-12 of Conference 7917
Date: Tuesday, 25 January 2011
Time: 11:00 AM 11:20 AM
Author(s): Jean-Christophe Delagnes, Patrick Mounaix, Lionel Canioni, Univ.
Bordeaux 1 (France)
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We present a theoretical investigation of a non-collinear sum frequency
generation in an electrooptic crystal between a visible and a THz radiation.
This results in the encoding of the spatial phase of the THz object field onto
the visible wave. We can thus record THz scene with conventional optical
detector that are much more sensitive than THz sensors. We show that a Nonlinear
Snell-Descartes' Lens Formula can be derived from our analysis; in comparison to
the classical one this generalized lens formula exhibits an additional
magnification factor proportional to the ratio between the optical and THz
wavelength.
Coherent monolithic THz generation based on quasi-phase-matched GaP bonding
structures pumped by pulsed fiber lasers at ~ 1.5 ตm
Paper 7917-16 of Conference 7917
Date: Tuesday, 25 January 2011
Time: 2:00 PM 2:20 PM
Author(s): Wei Shi, NP Photonics, Inc. (United States); Eliot B. Petersen, NP
Photonics, Inc. (United States) and The Univ. of Arizona (United States); Arturo
Chavez-Pirson, NP Photonics, Inc. (United States); Nasser Peyghambarian, NP
Photonics, Inc. (United States) and The Univ. of Arizona (United States)
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We report the coherent monolithic THz generation by using GaP QPM bonding
structures based on difference-frequency generation (DFG) pumped by the pulsed
fiber lasers in the C-band. The highest average power is about 10.9 uW at 1.5
THz by using 6-period GaP QPM bonding structure. Comparing with the single layer
GaP crystal, 6-period GaP QPM bonding structure has 26 times of enhancement in
THz generation. The azimuthal dependence of the THz generation for the GaP QPM
bonding structure has been measured when the polarization directions of two pump
beams are orthogonal and parallel, respectively.
Terahertz time-lapse video of hydration in physiological tissues
Paper 7938-20 of Conference 7938
Date: Thursday, 27 January 2011
Time: 10:10 AM 10:30 AM
Author(s): David B. Bennett, Zachary D. Taylor, Sijun Sung, Borokh Makkabi,
Priyamvada Tewari, Neha Bajwa, Rahul S. Singh, Martin O. Culjat, Warren S.
Grundfest M.D., Univ. of California, Los Angeles (United States); Elliott R.
Brown, Univ. of California, Santa Barbara (United States) and Wright State Univ.
(United States)
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This study describes terahertz (THz) imaging and monitoring of physiological
tissues over long periods of time based on high sensitivity to hydration levels.
A fast-scanning, gated time-domain THz imaging system (centered at 525 GHz; 125
GHz bandwidth) was utilized which uses dynamic pixel acquisition to image a
4-cm2 area in less than two minutes. THz video was taken on three sample
systems: (1) a simple binary system of water absorbed into a polypropylene
towel, (2) the accumulation of fluid to the site of a sulfuric acid burn on ex
vivo porcine skin, and (3) the evaporative dehydration of a porcine cornea. The
diffusion-regulating behavior of corneal and skin tissue is elucidated. We
conclude from this study that THz imaging can discern the differences between
diffusion of liquid water in physiological tissues and that of inanimate,
homogeneously-diffusing matter.
Investigation of metamaterials for terahertz frequency range
Paper 7917-13 of Conference 7917
Date: Tuesday, 25 January 2011
Time: 11:20 AM 11:40 AM
Author(s): Riad Yahiaoui, Univ. Bordeaux 1 (France); Hynek Nemec, Petr Kuel,
Filip Kadlec, Christelle Kadlec, Institute of Physics of the ASCR, v.v.i. (Czech
Republic); Jörg Schilling, Martin-Luther-Univ. Halle-Wittenberg (Germany); M.
Bari, Science and Technology Research Partners Ltd. (Ireland); Jean-Christophe
Delagnes, Patrick Mounaix, Univ. Bordeaux 1 (France)
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We have demonstrated theoretical and experimental investigation of fishnet
metamaterials at terahertz frequencies. Several prototypes were fabricated using
optical lithography or laser micromachining technique. We carried out
experiments using terahertz time domain spectroscopy THz-TDS. Moreover, we
proposed THz metamaterials showing a tunable spectral interval where the
magnetic permeability reaches negative values. This behavior was confirmed both
theoretically and experimentally. These demonstrated principles represent a step
forward towards a construction of a metamaterial with negative refractive index
capable to cover continuously a broad range of THz frequencies and opens a new
path for the active manipulation of submillimeter beams.
Upper limits on terahertz difference frequency generation power in quantum well
heterostructures
Paper 7953-29 of Conference 7953
Date: Tuesday, 25 January 2011
Time: 4:50 PM 5:10 PM
Author(s): Yong-Hee Cho, Texas A&M Univ. (United States); Mikhail A. Belkin, The
Univ. of Texas at Austin (United States); Alexey A. Belyanin, Texas A&M Univ.
(United States)
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We investigate the upper limits on the terahertz (THz) difference frequency
generation (DFG) power that can be achieved in intersubband quantum well systems
under external mid-infrared pumping. We solve self-consistently three coupled
wave equations, the Poisson equation, and density matrix equations including
pump depletions and nonlinear saturation effects. The maximal THz DFG power is
reached for intermediate pump intensities of the order of the saturation
intensity. Further increase of pump intensities degrades the maximum THz DFG
power and shifts it to large detunings. We compare our results with recent
experiments in GaInAs/AlInAs heterostructures and suggest optimal device
designs.
Comparison of GaAs and DAST electro-optic crystals for THz time domain
spectroscopy using 1.55 ตm fiber laser pulses
Paper 7938-6 of Conference 7938
Date: Thursday, 27 January 2011
Time: 9:50 AM 10:10 AM
Author(s): Matthieu Martin, Juliette Mangeney, Paul Crozat, Univ. Paris-Sud 11
(France); Patrick Mounaix, Univ. Bordeaux 1 (France)
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We report terahertz time-domain spectroscopy system based on Er:fiber laser at
1.55 ตm wavelength that integrate an ion-irradiated In0.53Ga0.47As
photoconductive antenna as emitter and a GaAs or a DAST electro-optic sensor as
detector. Detection using GaAs crystal is performed with an electro-optic
sampling detection based on polarization rotation of optical probe beam. We have
implemented interferometric scheme to detect the phase change of optical probe
beam due to THz-induced electro-optic effect in DAST crystal since the standard
electro-optic sampling technique is not applicable to DAST crystal. The detected
bandwidth is 3 THz using GaAs crystal and reaches 5 THz using DAST crystal.
A mechanically tunable terahertz modulator based on antiresonant reflecting
hollow waveguide
Paper 7938-11 of Conference 7938
Date: Thursday, 27 January 2011
Time: 1:50 PM 2:10 PM
Author(s): JaYu Lu, Hao-Zai Chen, National Cheng Kung Univ. (Taiwan); Chih-Hsien
Lai, Hung-Chun Chang, National Taiwan Univ. (Taiwan); Borwen You, National Cheng
Kung Univ. (Taiwan); Tze-An Liu, Jin-Long Peng, Industrial Technology Research
Institute (Taiwan)
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We have experimentally demonstrated a broadband tunable terahertz (THz)
modulator based on one-dimensional anti-resonant reflecting hollow waveguide
(ARRHW), which consisting of a PMMA-made cladding and a pair of
motorize-controlled metal plates located outside that. By continually varying
the distance d between the PMMA-cladding and the metal plate, it enables
dynamical tuning of the transmission band and linear attenuation of THz power
for a specific frequency. The measured maximum spectrum tuning range of 60GHz
and the power modulating depth of 20dB are achieved. The low loss THz-ARRHW
based device is also promising for the polarization filter application with
extinction-ratio of 20dB.
Phase-locking and synthesis of terahertz quantum cascade laser emission
Paper 7953-26 of Conference 7953
Date: Tuesday, 25 January 2011
Time: 3:30 PM 4:00 PM
Author(s): Stefano Barbieri, Marco Ravaro, Pierre Gellie, Univ. Paris 7-Denis
Diderot (France); Giorgio Santarelli, LNE-SYRTE, CNRS, UPMC (France); Christophe
Manquest, Carlo Sirtori, Univ. Paris 7-Denis Diderot (France); Suraj P. Khanna,
Edmund H. Linfield, Univ. of Leeds (United Kingdom)
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We demonstrate that the carrier frequency and the repetition rate of a Terahertz
(THz) quantum cascade laser (QCL) can be simultaneously phase-locked to the
repetition rate of a mode-locked Er-fiber laser. By combining the two
stabilization techniques we show that all the longitudinal modes of a multimode
QCL emitting at ~2.4THz can be phase-locked, paving the way to the use of these
sources for high power, direct THz frequency synthesis.
High peak power femtosecond pulse VECSELs for terahertz time domain spectroscopy
Paper 7919-38 of Conference 7919
Date: Tuesday, 25 January 2011
Time: 5:00 PM 5:15 PM
Author(s): Keith G. Wilcox, Aaron L. Chung, Adrian H. Quarterman, Zakaria
Mihoubi, Univ. of Southampton (United Kingdom); Ian Farrer, Harvey E. Beere,
David A. Ritchie, Univ. of Cambridge (United Kingdom); Vasilis Apostolopoulos,
Anne C. Tropper, Univ. of Southampton (United Kingdom)
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We report on a high peak power femtosecond modelocked VECSEL and its application
as a driving laser for an all-semiconductor terahertz-time-domain spectrometer.
The VECSEL produced near-transform-limited 335 fs sech2 pulses at a fundamental
repetition rate of 1 GHz, a centre wavelength of 999 nm and an average output
power of 120 mW. We report on the effect that this high peak power and short
pulse duration has on our generated THz signal, where an increase in the THz
power and bandwidth is observed.
Development of broadband optical frequency resource over 8.4-THz in 1.0-ตm
waveband for photonic transport systems
Paper 7958-14 of Conference 7958
Date: Wednesday, 26 January 2011
Time: 5:10 PM 5:30 PM
Author(s): Naokatsu Yamamoto, National Institute of Information and
Communications Technology (Japan); Yu Omigawa, Yuta Kinoshita, Aoyama Gakuin
Univ. (Japan); Atsushi Kannno, Kouichi Akahane, Tetsuya Kawanishi, National
Institute of Information and Communications Technology (Japan); Hideyuki
Sotobayashi, Aoyama Gakuin Univ. (Japan)
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For an enhancing usable optical frequency resources in a future photonic network
system, we have recently focused on a use of a novel wavelength band such as a
1-ตm waveband (Thousand-band: T-band) together with the conventional C- and
L-bands. In this study, we develop broadband potentialities in the T-band. An
error-free 10-Gbps photonic transmission over a few-km long holey-fiber is
successfully demonstrated for the wavelength range of 1037-1068-nm, which
corresponds to the optical frequency range of 8.4-THz. Pioneering a broadband
optical frequency resources is positively applied for a
wavelength-division-multiplex network in the T-band.
Reflection modality continuous-wave terahertz imaging of non-melanoma skin
cancers
Paper 7883A-19 of Conference 7883A
Date: Saturday, 22 January 2011
Time: 4:30 PM 4:50 PM
Author(s): Cecil S. Joseph, Anna N. Yaroslavsky, Univ. of Massachusetts Lowell
(United States); Victor A. Neel, Harvard Medical School (United States); Thomas
M. Goyette, Robert H. Giles, Univ. of Massachusetts Lowell (United States)
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Continuous-wave terahertz imaging has the potential for diagnosing and
delineating skin cancers. Specimens of human nonmelanoma skin cancers were
obtained from Mohs surgeries at Massachusetts General Hospital. The tissue was
sectioned and mounted in between slides of z-cut quartz for terahertz imaging.
Reflection measurements of 240ตm thick sections of skin cancer tissue were taken
at two frequencies of 1.39 THz and 1.63 THz. The terahertz sources used were two
CO2 pumped Far-Infrared molecular gas lasers. For detecting the terahertz
radiation liquid Helium cooled Silicon bolometers were used. The resolution of
the terahertz imaging system was 0.5 mm. The resulting terahertz images were
compared to the H&E histology of adjacent sections of the imaged tissue. The
preliminary results of the imaging experiments will be presented and discussed.
Time resolved spectroscopy on quantum dots and graphene at the FELBE
free-electron laser
Paper 7937-7 of Conference 7937
Date: Sunday, 23 January 2011
Time: 11:35 AM 12:00 PM
Author(s): Stephan F. Winnerl, Dominik Stehr, Harald Schneider, Manfred Helm,
Wolfgang Seidel, Peter Michel, Forschungszentrum Dresden-Rossendorf e.V.
(Germany); Evgeny Zibik, Ben Carpenter, Nathan Porter, Maurice S. Skolnick, Luke
R. Wilson, The Univ. of Sheffield (United Kingdom); Thomas Grange, Robson
Ferreira, Gerald Bastard, Ecole Normale Supérieure (France); Milan Orlita,
Paulina Plochocka, Piotr Kossacki, Marek Potemski, Grenoble High Magnetic Field
Lab. (France); Mike Sprinkle, Clair Berger, Walt de Heer, Georgia Institute of
Technology (United States)
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The relaxation dynamics in self-assembled quantum dots as well as in graphene is
studied by pump probe experiments using the free-electron laser FELBE at the
Forschungszentrum Dresden-Rossendorf. This laser provides picosecond radiation
pulses in the wavelength range 5 - 280 ตm. For the quantum dots long relaxation
times (1.5 ns) are found for level separations of 14 meV (3.4 THz), decreasing
very strongly to 2 ps at 30 meV (7 THz), in very good agreement with our
microscopic theory of the carrier relaxation process. For graphene relaxation
times ~ 20 ps are observed for excitations below the optical phonon energy.
Monolithic focal plane arrays for terahertz active spectroscopic imaging: an
experimental study
Paper 7945-31 of Conference 7945
Date: Monday, 24 January 2011
Time: 8:00 AM 8:20 AM
Author(s): Michele Ortolani, Roberto Casini, Fabio Chiarello, Sara Cibella,
Alessandra Di Gaspare, Istituto di Fotonica e Nanotecnologie (Italy); Florestano
Evangelisti, Istituto di Fotonica e Nanotecnologie (Italy) and Univ. Roma Tre
(Italy); Vittorio Foglietti, Ennio Giovine, Roberto Leoni, Guido Torrioli,
Istituto di Fotonica e Nanotecnologie (Italy); Alessandro Tredicucci, Scuola
Normale Superiore di Pisa (Italy); Miriam S. Vitiello, National Research Council
(Italy); Gaetano Scamarcio, Univ. di Bari (Italy)
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Imaging arrays of direct detectors in the 0.5-5 THz range have been developed
using three different detector technologies: i) Nb superconducting air-bridge
microbolometers; ii) GaAs Schottky diodes with air-bridge sub-micron anodes;
iii) AlGaN/GaN field-effect transistors with 0.15 micron Schottky T-gate length.
Terahertz active spectroscopic imaging was performed by illuminating the target
with two amplitude-modulated quantum cascade lasers (QCL) emitting at 2.5 and
2.8 THz, demodulated at the detector readout level. Performances, requirements
and costs of the different detector technologies are compared.
Accelerated 3D FDTD modeling of terahertz propagation in tissue using graphics
processing units (GPUs)
Paper 7897-14 of Conference 7897
Date: Monday, 24 January 2011
Time: 2:40 PM 3:00 PM
Author(s): Michael L. Doroski, Michael Knight, Jason A. Payne, Jessica E.
Grundt, Bennett L. Ibey, Robert J. Thomas, William P. Roach, Gerald J. Wilmink,
Air Force Research Lab. (United States)
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In this study, we developed 3-D FDTD thermal propagation code to model Terahertz
radiation propagation in biological tissues. We used graphics processing units
(GPUs) and coded in CUDA, an extension of the C language. We modeled the thermal
deposition of THz radiation for both in vitro and in vivo exposures. To
determine the speedup provided by GPUs, we compared the performance of
simulations performed on a GPU (Tesla C1060) and CPU
(Quad-Core,Intel-Xeon-5300). For the in vivo THz exposures, using a six-layer
skin model, we found that the GPU performed 3-D simulations roughly 90X faster
than the CPU.
Optical pump-terahertz probe studies of AlGaN
Paper 7939-42 of Conference 7939
Date: Tuesday, 25 January 2011
Time: 5:00 PM 5:20 PM
Author(s): Timothy M. Sweeney, Univ. of Oregon (United States); Grace D.
Metcalfe, Gregory A. Garrett, Anand V. Sampath, Paul H. Shen, U.S. Army Research
Lab. (United States); Hailin Wang, Univ. of Oregon (United States); Michael
Wraback, U.S. Army Research Lab. (United States)
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We report on ultrafast optical pump and terahertz probe studies of free-carrier
dynamics in AlGaN materials grown with and without nano-scale compositional
inhomogeneities (NCI). We observe an initial fast decrease of the transmitted
THz signal in both AlGaN samples due to the generation of photoexcited
free-carriers. The NCI AlGaN material shows a subsequent fast decrease in THz
absorption, as compared to the NCI-free AlGaN. The faster decay time in the NCI
AlGaN sample could be due to the transfer of free-carriers into NCI states from
the AlGaN matrix as well as exciton formation and carrier recombination.
Synchronized dual wavelength programmable laser with 75nm wavelength difference
tuning
Paper 7914-99 of Conference 7914
Date: Tuesday, 25 January 2011
Time: 6:00 PM
Author(s): Bryan Buorgoyne, Youngjae Kim, Alain Villeneuve, Genia Photonics Inc.
(Canada)
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Today, most tuneable fiber-based lasers generating dual wavelengths yield
identical spacing between the wavelengths while tuning. Having variable spacing
between the wavelengths would give way to a tuneable THz source, up to 10 THz,
through difference frequency generation. We present here such a source which is
a programmable laser based on an actively mode-locked dispersion-tuned
picosecond fiber laser delivering two wavelengths in the C and L bands
respectively. The difference between these wavelengths is rapidly adjustable
over a 75 nm band while the laser is tuning. Laser pulses are as short as 30 ps.
Ultrafast terahertz spectroscopy of few-layer graphene
Paper 7937-64 of Conference 7937
Date: Wednesday, 26 January 2011
Time: 2:40 PM 3:05 PM
Author(s): Hyunyong Choi, Ferenc Borondics, David A. Siegel, Shuyun Zhou,
Michael C. Martin, Alessandra Lanzara, Robert A. Kaindl, Lawrence Berkeley
National Lab. (United States)
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Graphene is attracting significant interest due to the unique physics of its 2D
charge carriers in a linear electronic bandstructure, and due to possible
applications in e.g. high-speed electronics. Here, we discuss the broadband
optical conductivity and ultrafast THz dynamics of graphene in the few-layer
limit. The equilibrium optical response in epitaxial graphene is consistent with
the electrodynamics of a dense Dirac electron plasma, arising from highly-doped
layers at the graphene-substrate interface. We will further discuss the
transient THz response, which reflects the recombination dynamics and unusual
Drude response of graphene and its dependence on the carrier distribution
function.
Optical frequency conductance model of teraHertz/infrared emission and detection
in quantum wells, quantum dots, and narrow-gap semiconductors
Paper 7938-9 of Conference 7938
Date: Thursday, 27 January 2011
Time: 11:40 AM 12:00 PM
Author(s): Thomas Szkopek, Elizabeth Ledwosinska, McGill Univ. (Canada)
Hide Abstract Add to My Schedule
The optical frequency conductance is derived for quantum wells and quantum dots,
and the optical frequency conductivity of bulk narrow-gap semiconductors is
revisited. The teraHertz (THz) and infrared (IR) response of these structures,
in free-space and guided-wave geometries, is simply described within the optical
frequency conductance formalism. The fine structure constant of quantum
electrodynamics sets the natural scale for the optical conductance of
semiconductor structures. Rules of thumb and physical limits to THz/IR gain and
absorption can be derived. The optical conductance formalism is applied to MCT
photodetectors, quantum well IR photodetectors, quantum dot IR photodetectors,
and quantum cascade lasers.
Of Light, Electrons, and Metamaterials
Date: Wednesday, 26 January 2011
Time: 10:30 AM 11:10 AM
Author(s):
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Nader Engheta, Univ. of Pennsylvania (USA)
Abstract: Metamaterials are engineered composite media formed by collections of
properly designed subwavelength elements and inclusions. Owing to the ability to
tailor their material parameters to desired values, metamaterials may manipulate
and control microwave, THz, IR and optical signals at various length scales.
When we merge the concept of extreme-parameter metamaterials with the fields of
nanooptics and nanoelectronics, various interesting possibilities may arise.
These include metamaterial-inspired optical nanocircuitry ("metatronics"),
graphene-based metamaterials and transformation optics and electronics for
taming and routing photons and electrons on 'flatland' structures, supercoupling
in narrow channels, and control of one-way flow of photons and electrons in
desired directions. In this talk, I review these concepts and forecast future
possibilities and directions.
Biography: Nader Engheta is the H. Nedwill Ramsey Professor of Electrical and
Systems Engineering and Professor of Bioengineering at the University of
Pennsylvania. He received his Ph.D. from Caltech. Selected as one of the
Scientific American magazine 50 Leaders in Science and Technology in 2006, he is
a Guggenheim Fellow, an IEEE Third Millennium Medalist, Fellow of IEEE, OSA,
APS, and AAAS, and the recipient of the 2008 George H. Heilmeier Award for
Excellence in Research, Fulbright Naples Chair Award, NSF Presidential Young
Investigator award, and several teaching awards.
Subpicosecond Sub-terahertz soliton laser based on a C-MOS compatible integrated
microring resonator
Paper 7945-37 of Conference 7945
Date: Monday, 24 January 2011
Time: 9:55 AM 10:10 AM
Author(s): Marco Peccianti, Institut National de la Recherche Scientifique
(Canada) and Institute for Chemical and Physical Processes (Italy); Alessia
Pasquazi, Yongwoo Park, Institut National de la Recherche Scientifique (Canada);
Brent Little, Sai-Tak Chu, Infinera Corp. (United States); David J. Moss, Univ.
of Sydney (Australia); Roberto Morandotti, Institut National de la Recherche
Scientifique (Canada)
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We present a novel subpicosecond, Sub THz -repetition rate, passively
mode-locked laser scheme based on high-harmonic four wave mixing in an
integrated CMOS-compatible high-Q nonlinear ring resonator.
Modified Sellmeier equation for ZnGeP2 in the 0.97-1640ตm range
Paper 7917-67 of Conference 7917
Date: Tuesday, 25 January 2011
Time: 6:00 PM
Author(s): Nobuhiro Umemura, Chitose Institute of Science and Technology (Japan)
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This paper reports the modified Sellmeier equations for ZnGeP2 (ZGP) that
provide excellent reproduction of the phase-matching conditions for DFG between
the two CO2 laser wavelengths, and the Nd:YAG laser and the Nd:YAG laser-pumped
OPO in the THz region. Model calculations based on these Sellmeier equations
strongly indicate that there is no significant difference in the refractive
indices of the non-annealed and annealed crystals from 1.0642ตm to 1640ตm
(0.18THz).
Novel concept for long-haul ultrashort pulse fiber delivery without pre-chirping
Paper 7912-41 of Conference 7912
Date: Wednesday, 26 January 2011
Time: 8:20 AM 8:40 AM
Author(s): Tuan Le, Gabriel Tempea, Andreas Stingl, FEMTOLASERS Produktions GmbH
(Austria); Kim G. Jespersen, OFS Fitel Denmark ApS (Denmark); Karin Wiesauer,
RECENDT GmbH (Austria)
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Ultrashort pulse fiber delivery for Ti:Sapphire lasers is basically restricted
to distances below several meters which is due to the application of dispersion
compensating devices that are not capable managing third and higher order
material dispersion. By the use of a novel fiber delivery concept ultrashort
laser pulses in the 800 nm wavelength range can now be transmitted over tens of
meters without the need for any pulse pre-compression. For the first time a
long-haul fiber delivery module will be demonstrated revealing its potential for
remote imaging or THz spectroscopy with femtosecond laser pulses.
Rigorous characterization of surface plasmon modes by using the finite element
method
Paper 7941-34 of Conference 7941
Date: Wednesday, 26 January 2011
Time: 8:30 AM 8:50 AM
Author(s): B. M. Azizur Rahman, Huda Tanvir, Anita Quadir, Ken Grattan, The City
Univ. (United Kingdom)
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A rigorous full vectorial finite element-based approach has been developed to
characterize a wide range of plasmonic devices, both at optical and terahertz
frequencies. Results for wave confinement in gold nanowires, air-core guides and
defect-core metal coated photonic crystal fibers and gain threshold optimization
of quantum cascaded lasers for terahertz (THz) frequencies will be presented.
Optimization of organic NLO materials for integration with silicon photonic,
plasmonic (metal optics), and metamaterial devices (Keynote Presentation)
Paper 7935-1 of Conference 7935
Date: Monday, 24 January 2011
Time: 8:10 AM 8:50 AM
Author(s): Larry R. Dalton, Univ. of Washington (United States)
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The fast response of organic nonlinear optical materials together with the
potential for large optical nonlinearities makes these materials attractive for
the integration with silicon photonic, plasmonic, and metamaterial device
architectures. For example, incorporation of organic nonlinear optical materials
into slotted silicon photonic waveguide device structures leads to dramatic
improvement in the "effective" nonlinearity of organic materials. Drive voltages
approaching 0.1 V have been realized for electro-optic modulation and low
control power all-optical modulation has been demonstrated to approximately 10
THz. While organic nonlinear optical materials in general exhibit excellent
processability-being amenable to both solution and vapor phase deposition and to
a variety of processing methodologies ranging from crystal growth, to
sequential-synthesis/self-assembly, to electrical and optical field poling-the
special device architectures of silicon photonics, plasmonics (metal optics),
and metamaterials can present challenges to useful integration. New organic
nonlinear optical material concepts, materials, and processing options will be
introduced and discussed.
The relevance of positive differential conductivity for quantum cascade lasers
Paper 7953-21 of Conference 7953
Date: Tuesday, 25 January 2011
Time: 11:10 AM 11:40 AM
Author(s): Andreas Wacker, Lund Univ. (Sweden)
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A central feature of Quantum Cascade Lasers (QCLs) is the periodic repetition of
identical active structures forming the cascade for the electron flow through
the device. For operation, the bias must drop homogeneously over the entire
structure which requires the presence of positive differential conductivity in
each period as otherwise domains with different electric field will form. As the
gain transition itself is associated with a source of negative differential
conductivity, this has to be balanced by other processes. This feature is
discussed in detail and various strategies are discussed, which help in the
classification of existing device concepts. Exemplary simulation results are
shown including a new THz design which should operate well above 200 K.
High-temperature performance and broad continuous tunability of terahertz
quantum-cascade lasers
Paper 7953-23 of Conference 7953
Date: Tuesday, 25 January 2011
Time: 1:30 PM 2:00 PM
Author(s): Sushil Kumar, Lehigh Univ. (United States); Qi Qin, Chun W. I. Chan,
Qing Hu, Massachusetts Institute of Technology (United States); John L. Reno,
Sandia National Labs. (United States)
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We demonstrate a terahertz quantum-cascade laser (QCL) operating significantly
above the temperature of hw/kB, which has so-far been an empirical limitation
for such devices. A 1.8 THz QCL operating up to a temperature of 1.9hw/kB (163K)
is realized, with more than 3mW of peak optical power output at 150K. We also
demonstrate broadly tunable terahertz QCLs. Discontinuous tuning over a range of
165GHz is realized for a 4.4THz QCL using an antireflection-coated silicon lens
to reduce facet reflection and as a beam-forming element, with an external
grating providing frequency selective optical feedback. We have also realized
continuous tuning of 137GHz for a 3.8THz QCL with a unique concept of altering
the lateral mode profile of terahertz "wire-lasers" to achieve broad tuning.
Trends in nanoplasmonics: ultrasmall, ultrafast, ultrastrong
Paper 7937-42 of Conference 7937
Date: Tuesday, 25 January 2011
Time: 1:30 PM 1:55 PM
Author(s): Mark I. Stockman, Georgia State Univ. (United States)
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Nanoplasmonics deals with collective electron dynamics on the surface of metal
nanostructures, which arises as a result of excitations called surface plasmons.
The surface plasmons localize and concentrate optical energy in nanoscopic
regions creating highly enhanced local optical fields. They undergo ultrafast
dynamics with timescales as short as a few hundred attoseconds. From the latest
developments and original work in nanoplasmonics, we will consider SPASER
(quantum nanoscale optical generator and ultrafast amplifier), ultrafast
coherent control on the nanoscale, generation of EUV radiation by plasmonic
enhancement, adiabatic nano-concentration of optical energy, and SPIDER
(surface-plasmon-induced drag-effect rectification) that leads to generation of
nanoscale THz fields by femtosecond polaritonic pulses in metal nanowires.
Spontaneous and stimulated Raman scattering in planar silicon waveguides
Paper 7943-40 of Conference 7943
Date: Tuesday, 25 January 2011
Time: 3:10 PM 3:30 PM
Author(s): Sha Wang, Stefan Meister, Shaimaa Mahdi, Bülent Franke, Aws Al-Saadi,
Technische Univ. Berlin (Germany); Lars Zimmermann, Harald H. Richter, David
Stolarek, IHP GmbH (Germany); Viktor Lisinetskii, Sigurd K. Schrader, Technische
Fachhochschule Wildau (Germany); Hans Eichler, Technische Univ. Berlin (Germany)
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Raman scattering in planar silicon on insulator (SOI) waveguides with 2 microm
width, 220 nm height and 2 cm length is investigated. Spontaneous Raman
scattering is observed with as low as 2.5 mW pump power inside the waveguide.
The Raman shift is measured as 15.6 THz, while the FWHM of Raman spectrum is
measured as around 100 GHz. Maximum Raman output of around 90 pW is obtained by
around 22 mW pump. The stimulated Raman gain coefficient is estimated as around
56 cm/GW from the relationship between spontaneous Raman output power and pump
power. A temperature dependence of Raman frequency shift of about 0.6 GHz/K is
measured. The spontaneous anti-Stokes Raman scattering output peak at 1253 nm is
also observed with around 35 mW pump. Stimulated Raman amplification measurement
is carried out with a SLED white light source as probe signal. With 35 mW pump
power, around 0.6 dB gain has been determined with both pump and probe being TE
polarized.
Novel aspects of pulse propagation in photonic crystal fibers
Paper 7946-33 of Conference 7946
Date: Wednesday, 26 January 2011
Time: 8:50 AM 9:20 AM
Author(s): Sebastian P. Stark, Alexander V. Podlipensky, Philip S. Russell,
Max-Planck Institute for the Science of Light (Germany)
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Unconventional wavelength-dependent group velocity dispersion, designed and
realised in solid-core photonic crystal fibers (PCFs), can give rise to unusual
pulse dynamics. Broad-band supercontinua can be generated in the visible
spectral range, with high conversion efficiencies that can be further enhanced
by frequent inter-soliton collisions. The high nonlinearity of small-core PCFs,
along with a strongly uncompensated pulse chirp, can be used to trigger pulse
breakup, leading to the generation of ultrashort THz pulse trains. Experimental
and numerical results on the propagation of femtosecond pulses in
axially-varying tapered PCF structures will also be discussed.
Giant lasing effect in magnetic nanoconductors and its detection by DC
electrical measurements
Paper 7933-51 of Conference 7933
Date: Wednesday, 26 January 2011
Time: 5:00 PM 5:20 PM
Author(s): Anatoly M. Kadygrobov, Robert I. Shekhter, Univ. of Gothenburg
(Sweden); Sergei I. Kulinich, Univ. of Gothenburg (Sweden) and Institute for Low
Temperature Physics and Engineering (Ukraine); Mats Jonson, Univ. of Gothenburg
(Sweden)
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We propose a new principle for a solid-state laser in 1-100 THz regime based on
a new mechanism for creating spin-flip processes in ferromagnetic conductors.
The mechanism is due to the dependence of the electron spin - magnetic moment
exchange interaction on the electron momentum. We predict a giant lasing effect
which provides the optical gain exceeding the one of conventional semiconductor
lasers by 4 or 5 orders of magnitude. This effect may be detected by electrical
measurements. We show that the relative change of the resistance of a
ferromagnetic point contact under irradiation is proportional to the power of
the stimulated emission of photons from the point contact.
Efficient material parameters estimation with terahertz time domain spectroscopy
Paper 7938-4 of Conference 7938
Date: Thursday, 27 January 2011
Time: 9:10 AM 9:30 AM
Author(s): Osman S. Ahmed, Mohamed A. Swillam, Mohamed H. Bakr, Xun Li, McMaster
Univ. (Canada)
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We propose a novel optimization technique for the estimation of material
refractive index in the terahertz frequency range. The algorithm is applied for
materials with arbitrary frequency dependence. Dispersive dielectric models are
embedded for accurate parameter extraction of a sample with unknown thickness.
Instead of solving N expensive nonlinear optimization problems with different
possible material thickness, our technique obtains the optimal material
thickness by solving only one optimization problem. Our approach has been
successfully illustrated through a number of examples with different dispersive
models. The examples include the characterization of doped semiconductors used
in surface plasmon plaritons in the THz regime.
Optical nano-antennas: a new approach for optical imaging and detection
Paper 7945-82 of Conference 7945
Date: Wednesday, 26 January 2011
Time: 2:45 PM 3:05 PM
Author(s): Jacob Scheuer, Inbal Freidler, Yuval Yifat, Zeev Iluz, Michal Eitan,
Yael Hanein, Amir Boag, Tel Aviv Univ. (Israel)
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During the past few years, the field of optical nano-Antennas has experience
extensive growth in activity and has been receiving much focus and attention,
primarily due to their possible applications in telecommunications, field
enhancement, sensing and solar energy harvesting. A Rectenna (Rectifying
antenna) is composed of an antenna connected to a rectifying component (e.g. a
diode), which enable direct conversion of electromagnetic energy to direct
electrical current. The concept, originally proposed in Raytheon during the 60s,
was aiming at achieving highly efficient power transfer and indeed, power
conversion efficiencies exceeding 80% have been demonstrated in RF frequencies.
An attempt to push this concept to the optical domain encounters two primary
hurdles: the fabrication of extremely small structures and realizing very high
bandwidth (10-1000 THz) diodes. Employing state-of-the-art nano-fabrication
tools and extremely high-mobility carbon nano-tubes for the rectification diode,
we believe it is possible to realize a rectenna operating at the far to near IR
bands and maybe even at the visible band as well. Nano-antenna array operating
at telecom wavelength are demonstrated experimentally and their spectral
properties are studied in detail exhibiting excellent agreement with the
theoretical analysis. Applications in the field of imaging and
telecommunications will be presented and discussed.
Recent progress of THz generation and detection in ambient air or gases
Paper 7917-15 of Conference 7917
Date: Tuesday, 25 January 2011
Time: 1:30 PM 2:00 PM
Author(s): Xiaofei Lu, Benjamin W. Clough, I-Chen Ho, Jingle Liu, Jianming Dai,
Xi-Cheng Zhang, Rensselaer Polytechnic Institute (United States)
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THz time domain spectroscopy has been largely applied on the measurement of
semiconductor, electro-optic crystals, and selected chemical, biological and
explosive materials. Here we will highlight THz gas photonics and its
applications, with an emphasis on spectroscopic capabilities. The most recent
results of using air (and selected gases) as the emitter and sensor material for
both generation and detection of broadband THz waves will also be reported. Air,
especially ionized air (plasma), has been used to generate intense peak THz
waves (THz field > 1.5 MV/cm) with a broadband spectrum (10% bandwidth from 0.1
THz to 46 THz).
High peak power femtosecond pulse VECSELs for terahertz time domain spectroscopy
Paper 7919-38 of Conference 7919
Date: Tuesday, 25 January 2011
Time: 5:00 PM 5:15 PM
Author(s): Keith G. Wilcox, Aaron L. Chung, Adrian H. Quarterman, Zakaria
Mihoubi, Univ. of Southampton (United Kingdom); Ian Farrer, Harvey E. Beere,
David A. Ritchie, Univ. of Cambridge (United Kingdom); Vasilis Apostolopoulos,
Anne C. Tropper, Univ. of Southampton (United Kingdom)
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We report on a high peak power femtosecond modelocked VECSEL and its application
as a driving laser for an all-semiconductor terahertz-time-domain spectrometer.
The VECSEL produced near-transform-limited 335 fs sech2 pulses at a fundamental
repetition rate of 1 GHz, a centre wavelength of 999 nm and an average output
power of 120 mW. We report on the effect that this high peak power and short
pulse duration has on our generated THz signal, where an increase in the THz
power and bandwidth is observed.
Multi-THz fields exceeding 100 MV/cm: an ultrabroadband source for sub-cycle
nonlinear optics
Paper 7917-11 of Conference 7917
Date: Tuesday, 25 January 2011
Time: 10:30 AM 11:00 AM
Author(s): Alexander Sell, Friederike Junginger, Olaf Schubert, Bernhard Mayer,
Univ. Konstanz (Germany); Tobias Kampfrath, Martin Wolf, Fritz-Haber-Institut
der Max-Planck-Gesellschaft (Germany); Daniele Brida, Marco Marangoni, Giulio
Cerullo, Politecnico di Milano (Italy); Alfred Leitenstorfer, Rupert Huber,
Univ. Konstanz (Germany)
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We present a table-top source of extremely intense multi-THz transients covering
the spectral regime between 0.1 and 140 THz. Electric field amplitudes of up to
108 MV/cm and pulse durations as short as a single cycle are demonstrated with
our hybrid Er:fiber-Ti:sapphire laser system. All THz waveforms are
electro-optically detected. The multi-branch fiber laser generates gate pulses
as short as 4.3 fs. Our high-field THz facility opens the door to extremely
nonlinear optics in a previously hard-to-access spectral regime. First
applications include THz coherent control and four-wave mixing studies as well
as all-magnetic control of coherent spin waves.
Reflection modality continuous-wave terahertz imaging of non-melanoma skin
cancers
Paper 7883A-19 of Conference 7883A
Date: Saturday, 22 January 2011
Time: 4:30 PM 4:50 PM
Author(s): Cecil S. Joseph, Anna N. Yaroslavsky, Univ. of Massachusetts Lowell
(United States); Victor A. Neel, Harvard Medical School (United States); Thomas
M. Goyette, Robert H. Giles, Univ. of Massachusetts Lowell (United States)
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Continuous-wave terahertz imaging has the potential for diagnosing and
delineating skin cancers. Specimens of human nonmelanoma skin cancers were
obtained from Mohs surgeries at Massachusetts General Hospital. The tissue was
sectioned and mounted in between slides of z-cut quartz for terahertz imaging.
Reflection measurements of 240ตm thick sections of skin cancer tissue were taken
at two frequencies of 1.39 THz and 1.63 THz. The terahertz sources used were two
CO2 pumped Far-Infrared molecular gas lasers. For detecting the terahertz
radiation liquid Helium cooled Silicon bolometers were used. The resolution of
the terahertz imaging system was 0.5 mm. The resulting terahertz images were
compared to the H&E histology of adjacent sections of the imaged tissue. The
preliminary results of the imaging experiments will be presented and discussed.
Ultrafast carrier capture and THz resonances in InGaAs quantum posts
Paper 7937-2 of Conference 7937
Date: Sunday, 23 January 2011
Time: 9:10 AM 9:35 AM
Author(s): Dominik Stehr, Univ. of California, Santa Barbara (United States) and
Forschungszentrum Dresden-Rossendorf e.V. (Germany); Christopher M. Morris,
Univ. of California, Santa Barbara (United States); Diyar Talbalyev, Los Alamos
National Lab. (United States); Martin Wagner, Forschungszentrum
Dresden-Rossendorf e.V. (Germany); Hyochul Kim, Univ. of California, Santa
Barbara (United States); Antoinette J. Taylor, Los Alamos National Lab. (United
States); Harald Schneider, Forschungszentrum Dresden-Rossendorf e.V. (Germany);
Pierre M. Petroff, Mark S. Sherwin, Univ. of California, Santa Barbara (United
States)
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Semiconductor quantum posts - nanowire-like InGaAs heterostructures in a GaAs
matrix - were investigated with respect to their carrier capture dynamics after
photoexcitation into the GaAs matrix. The results of the THz experiment
demonstrate that after ultrafast excitation, electrons relax within a few
picoseconds into the quantum posts, which act as efficient traps. Saturation of
the quantum post states, probed by time-resolved photoluminescence, was reached
at approximately ten times the quantum post density. Additionally, possible
electronic THz resonances with a dipole moment in the growth direction were
probed showing a broad response around 1.5 THz.
Time resolved spectroscopy on quantum dots and graphene at the FELBE
free-electron laser
Paper 7937-7 of Conference 7937
Date: Sunday, 23 January 2011
Time: 11:35 AM 12:00 PM
Author(s): Stephan F. Winnerl, Dominik Stehr, Harald Schneider, Manfred Helm,
Wolfgang Seidel, Peter Michel, Forschungszentrum Dresden-Rossendorf e.V.
(Germany); Evgeny Zibik, Ben Carpenter, Nathan Porter, Maurice S. Skolnick, Luke
R. Wilson, The Univ. of Sheffield (United Kingdom); Thomas Grange, Robson
Ferreira, Gerald Bastard, Ecole Normale Supérieure (France); Milan Orlita,
Paulina Plochocka, Piotr Kossacki, Marek Potemski, Grenoble High Magnetic Field
Lab. (France); Mike Sprinkle, Clair Berger, Walt de Heer, Georgia Institute of
Technology (United States)
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The relaxation dynamics in self-assembled quantum dots as well as in graphene is
studied by pump probe experiments using the free-electron laser FELBE at the
Forschungszentrum Dresden-Rossendorf. This laser provides picosecond radiation
pulses in the wavelength range 5 - 280 ตm. For the quantum dots long relaxation
times (1.5 ns) are found for level separations of 14 meV (3.4 THz), decreasing
very strongly to 2 ps at 30 meV (7 THz), in very good agreement with our
microscopic theory of the carrier relaxation process. For graphene relaxation
times ~ 20 ps are observed for excitations below the optical phonon energy.
Tapered terahertz plasmonic waveguides
Paper 7937-9 of Conference 7937
Date: Sunday, 23 January 2011
Time: 1:30 PM 1:55 PM
Author(s): Daniel M. Mittleman, Hui Zhan, Jingbo Liu, Rajind Mendis, Rice Univ.
(United States)
No abstract available Add to My Schedule
Ultrafast optical control of terahertz surface plasmons in subwavelength
hole-arrays at room temperature
Paper 7937-10 of Conference 7937
Date: Sunday, 23 January 2011
Time: 1:55 PM 2:20 PM
Author(s): Abul K. Azad, Los Alamos National Lab. (United States)
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Ultrafast switching or modulation of the resonant behavior of the 2-D metallic
arrays in terahertz frequencies is of particular interest for high speed
communication and sensing applications. We demonstrate optical control of
surface plasmon enhanced resonant terahertz transmission in two-dimensional
subwavelength metallic hole arrays fabricated on gallium arsenide based
substrates. Optically pumping the arrays creates a conductive layer in the
substrate reducing the terahertz transmission amplitude of both the resonant
mode and the direct transmission. Under low optical fluence, the terahertz
transmission is more greatly affected by resonance damping than by propagation
loss in the substrate. An ErAs:GaAs nanoisland superlattice substrate is shown
to allow ultrafast control with a switching recovery time of ~10 ps.
Controlling THz plasmons with the electron spin state
Paper 7937-11 of Conference 7937
Date: Sunday, 23 January 2011
Time: 2:20 PM 2:35 PM
Author(s): Cameron J. E. Straatsma, Abdulhakem Y. Elezzabi, Univ. of Alberta
(Canada)
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We investigate the effects of photonic magnetoresistance on the propagation of
terahertz (THz) radiation in multilayered metallic media. These subwavelength
plasmonic structures contain alternating layers of ferromagnetic and
non-magnetic metal thin films, which allow for control over the electron spin
state. In particular, using THz time-domain spectroscopy, a photonic analogous
giant magnetoresistance effect is observed and its application in actively
controlling THz plasmons is studied. We demonstrate the possibility of
implementing this effect to produce active THz guided wave devices.
Ultrafast photoconductors based on subwavelength metallic gratings for the next
generation of photoconductive terahertz sources
Paper 7937-14 of Conference 7937
Date: Sunday, 23 January 2011
Time: 3:15 PM 3:30 PM
Author(s): Christopher W. Berry, Mona Jarrahi, Univ. of Michigan (United States)
Hide Abstract Add to My Schedule
We present a new generation of ultrafast and high quantum efficiency
photoconductors fabricated on high quality crystalline semiconductors. The
device consists of a metal-semiconductor-metal photoconductor with a
subwavelength contact electrode grating at the optical pump wavelength.
Ultrafast photocurrent impulse response and high quantum efficiency operation is
achieved through the excitation of surface plasmon waves, which significantly
enhance the concentration of photo-generated carriers in close proximity to
photoconductor contact electrodes. Ultrafast photocurrent impulse response times
as low as 100fs FWHM are estimated for the presented photoconductors, which are
faster than the photocurrent response of previously demonstrated photoconductors
with short carrier lifetime semiconductors.
Correction of tissue perfusion by terahertz waves
Paper 7901-17 of Conference 7901
Date: Sunday, 23 January 2011
Time: 4:45 PM 5:00 PM
Author(s): Alexey N. Ivanov, Vyacheslav F. Kirichuk, Tatyana S. Kiriyazi,
Saratov State Medical Univ. (Russian Federation)
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This work is about influence by electromagnetic therahertz waves at range on
frequencies of a molecular spectrum of radiation and absorption nitrogen oxide
150,176 - 150,664 GHz on microcirculation at white male rats, taking place in a
condition of sharp stress. It was shown, that waves of the specified range are
capable to restore infringements peripheral blood stream, characteristic for
sharp stress - reaction.
Monolithic focal plane arrays for terahertz active spectroscopic imaging: an
experimental study
Paper 7945-31 of Conference 7945
Date: Monday, 24 January 2011
Time: 8:00 AM 8:20 AM
Author(s): Michele Ortolani, Roberto Casini, Fabio Chiarello, Sara Cibella,
Alessandra Di Gaspare, Istituto di Fotonica e Nanotecnologie (Italy); Florestano
Evangelisti, Istituto di Fotonica e Nanotecnologie (Italy) and Univ. Roma Tre
(Italy); Vittorio Foglietti, Ennio Giovine, Roberto Leoni, Guido Torrioli,
Istituto di Fotonica e Nanotecnologie (Italy); Alessandro Tredicucci, Scuola
Normale Superiore di Pisa (Italy); Miriam S. Vitiello, National Research Council
(Italy); Gaetano Scamarcio, Univ. di Bari (Italy)
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Imaging arrays of direct detectors in the 0.5-5 THz range have been developed
using three different detector technologies: i) Nb superconducting air-bridge
microbolometers; ii) GaAs Schottky diodes with air-bridge sub-micron anodes;
iii) AlGaN/GaN field-effect transistors with 0.15 micron Schottky T-gate length.
Terahertz active spectroscopic imaging was performed by illuminating the target
with two amplitude-modulated quantum cascade lasers (QCL) emitting at 2.5 and
2.8 THz, demodulated at the detector readout level. Performances, requirements
and costs of the different detector technologies are compared.
Bound terahertz waves on meta-surfaces and active metamaterials
Paper 7945-32 of Conference 7945
Date: Monday, 24 January 2011
Time: 8:20 AM 8:40 AM
Author(s): Marco Rahm, Fraunhofer-Institut für Physikalische Messtechnik
(Germany) and Technische Univ. Kaiserslautern (Germany); Juan Luis Garcia Pomar,
Benjamin Reinhard, Jens Neu, Viktoria Wollrab, Oliver Paul, Rene Beigang,
Fraunhofer-Institut für Physikalische Messtechnik (Germany)
No abstract available Add to My Schedule
Phonon and polaron enhanced IR-THz photodetectors
Paper 7945-34 of Conference 7945
Date: Monday, 24 January 2011
Time: 9:00 AM 9:20 AM
Author(s): Hui Chun Liu, Chun-Ying Song, Zbigniew R. Wasilewski, Margaret
Buchanan, National Research Council Canada (Canada)
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We investigate the active use of phonons and polarons for realizing new
optoelectronics devices. We present an application of the concept to
photodetection in the infrared-terahertz spectrum. The ability to design a
phonon or polaron is the first step in making use of them. We show this by a
model system employing the electron intersubband excitation in quantum wells
coupled with phonon modes. This results in a photodetector with a high response
at the selected wavelength.
GaN for THz sources
Paper 7945-35 of Conference 7945
Date: Monday, 24 January 2011
Time: 9:20 AM 9:40 AM
Author(s): Michel Marso, Univ. du Luxembourg (Luxembourg)
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In this work we investigate the unique electrical and thermal performance of GaN
to improve two different approaches to generate THz radiation. One method is the
heterodyne photomixing, where the THz output power is restricted by the thermal
and electrical limits of the conventionally used LT GaAs. The aim of our work is
to increase the output power by replacing the LT GaAs with low-temperature grown
GaN. In the second approach GaN-based ultrafast high electron mobility
transistors are developed for use in a high power high frequency oscillator
circuit that acts as source for a frequency multiplier chain.
Terahertz emission from Mg-doped a-plane InN
Paper 7945-36 of Conference 7945
Date: Monday, 24 January 2011
Time: 9:40 AM 9:55 AM
Author(s): Hyeyoung Ahn, Yi-Jou Yeh, National Chiao Tung Univ. (Taiwan); Shangjr
Gwo, National Tsing Hua Univ. (Taiwan)
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We report terahertz emission from Mg-doped a-plane indium nitride (a-InN:Mg)
films with different carrier density, relative to the Mg-doped InN films grown
along the c-axis (c-InN:Mg). While intense terahertz emission (×500 than that of
undoped c-InN) from c-InN:Mg sharply decreases as the carrier density increases,
terahertz emission from a-InN:Mg is equally strong over the wide variation of
the carrier density. The primary terahertz radiation mechanism of both undoped
and Mg-doped a-InN film is due to the acceleration of photoexcited carriers
under the polarization-induced in-plane electric field perpendicular to the
a-axis and that of c-InN:Mg is due to the photo-Dember effect.
Ultrafast gain switching of quantum cascade lasers
Paper 7937-24 of Conference 7937
Date: Monday, 24 January 2011
Time: 10:35 AM 11:00 AM
Author(s): Sukhdeep S. Dhillon, Nathan Jukam, Dimitri Oustinov, Rakchanok
Rungsawang, Julien Madeo, Ecole Normale Supérieure (France); Stefano Barbieri,
Christophe Manquest, Carlo Sirtori, Univ. Paris 7-Denis Diderot (France); Suraj
P. Khanna, Edmund H. Linfield, Giles Davies, Univ. of Leeds (United Kingdom);
Jerome Tignon, Ecole Normale Supérieure (France)
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Terahertz (THz) time domain spectroscopy is now a widely used technique where it
is essential to know both the amplitude and phase of a THz wave. Nonetheless,
THz amplifiers, capable of increasing the THz wave field, are presently lacking.
In this context THz quantum cascade lasers (QCL) are very promising devices for
amplification. Gain clamping in these devices, however, limits the attainable
amplification. Here we circumvent gain clamping by coupling a THz QCL and an
integrated Auston-switch to perform ultrafast gain switching. The resulting
non-equilibrium gain is not clamped above laser threshold and large
amplification of input terahertz pulses is demonstrated.
Terahertz pulsed imaging in vivo
Paper 7897-11 of Conference 7897
Date: Monday, 24 January 2011
Time: 1:30 PM 2:00 PM
Author(s): Emma Pickwell-MacPherson, Hong Kong Univ. of Science and Technology
(Hong Kong, China)
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Terahertz (10^12 Hz) pulsed imaging is a relatively new technique with high
resolution (about 20 ตm) and has only emerged in the last five years as a
potential new clinical tool for medical imaging. It is a totally non-destructive
and non-ionising imaging modality as the average power of the pulse for
producing the radiation is as small as 100 nW. We use a prototype terahertz
probe to perform reflection geometry in vivo measurements of human skin. The
hand-held terahertz probe gives more flexibility than a typical flat-bed imaging
system, but it also results in noisier data and requires existing processing
methods to be improved.
THz techniques for human skin measurement
Paper 7897-12 of Conference 7897
Date: Monday, 24 January 2011
Time: 2:00 PM 2:20 PM
Author(s): Yu Guan, Takayuki Shibuya, Koji Suizu, Nagoya Univ. (Japan);
Shin'ichiro Hayashi, RIKEN (Japan); Kodo Kawase, Nagoya Univ. (Japan) and RIKEN
(Japan)
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We are developing several novel THz techniques for skin measurement. A
high-resolution tomographic imaging was demonstrated using a reflection-type
terahertz time-domain spectroscopy. The wideband spectrum of the terahertz waves
provided high-axial resolution of 5?m leading to tomographic imaging of
multilayered skin structure. Secondly, we have demonstrated a sensitive THz
imaging method using an interference effect. We applied this technique for the
thickness measurement of human skin adhered onto a sticky tape. Thirdly,
metal-mesh film can be used for sensing when samples adhere to the metal
surface. We report on the spectrum change of metal-mesh with horny layer.
Using the gene expression profile of jurkat cells to determine whether terahertz
(THz) radiation couples to DNA and impacts transcription processes
Paper 7897-13 of Conference 7897
Date: Monday, 24 January 2011
Time: 2:20 PM 2:40 PM
Author(s): Jessica E. Grundt, Benjamin D. Rivest, Caleb C. Roth, Bennett L.
Ibey, Michael L. Doroski, Jason A. Payne, William P. Roach, Gerald J. Wilmink,
Air Force Research Lab. (United States)
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Theoretical models suggest that 2.52 THz radiation couples directly to DNA and
affects transcriptional processes; however, this phenomenon has not been
empirically confirmed. In this study, we hypothesized that if THz radiation does
damage DNA then exposed cells will express known damage and repair genes. To
test this hypothesis, we irradiated Jurkat cells using a THz laser (2.52 THz,
252 mWcm-2, t=5-50 minutes), and evaluated their response using viability, qPCR,
and microarray techniques. We found several genes were markedly upregulated in
each THz exposure group; however, the majority encoded for heat shock proteins
and few for DNA repair proteins.
Accelerated 3D FDTD modeling of terahertz propagation in tissue using graphics
processing units (GPUs)
Paper 7897-14 of Conference 7897
Date: Monday, 24 January 2011
Time: 2:40 PM 3:00 PM
Author(s): Michael L. Doroski, Michael Knight, Jason A. Payne, Jessica E.
Grundt, Bennett L. Ibey, Robert J. Thomas, William P. Roach, Gerald J. Wilmink,
Air Force Research Lab. (United States)
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In this study, we developed 3-D FDTD thermal propagation code to model Terahertz
radiation propagation in biological tissues. We used graphics processing units
(GPUs) and coded in CUDA, an extension of the C language. We modeled the thermal
deposition of THz radiation for both in vitro and in vivo exposures. To
determine the speedup provided by GPUs, we compared the performance of
simulations performed on a GPU (Tesla C1060) and CPU
(Quad-Core,Intel-Xeon-5300). For the in vivo THz exposures, using a six-layer
skin model, we found that the GPU performed 3-D simulations roughly 90X faster
than the CPU.
Using nanoscale molecular dynamics modeling and Raman spectroscopy to
investigate the direct effect of Terahertz radiation on double-stranded DNA
Paper 7897-15 of Conference 7897
Date: Monday, 24 January 2011
Time: 3:00 PM 3:20 PM
Author(s): Gerald J. Wilmink, Jessica E. Grundt, Air Force Research Lab. (United
States); Brett R. Boyce, U.S. Air Force Academy (United States); James E. Parker
III, Air Force Research Lab. (United States) and The Univ. of Texas at San
Antonio (United States); Brady Mcmicken, The Univ. of Texas at San Antonio
(United States); Caleb C. Roth, Bennett L. Ibey, Michael L. Doroski, Benjamin A.
Rockwell, Robert J. Thomas, William P. Roach, Air Force Research Lab. (United
States)
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Theoretical models suggest that 2.52 Terahertz (THz) radiation can couple
directly to the natural breathing modes of double stranded DNA (dsDNA) resulting
in the creation of "bubbles" between dsDNA. In this study, we used Raman
spectroscopy and nanoscale molecular dynamics modeling (NAMD) tools to evaluate
the effect that 2.52 THz radiation has on the hydrogen bonding in dsDNA. Raman
spectra were collected as various wavelengths (414 nm, 514 nm) on both salmon
sperm dsDNA (~2-3k base pairs) and custom-designed dsDNA (polyA/T, 50bps).
Comparable analyses were also conducted for hyperthermic and UV
positive-controls.
Carrier dynamics of Mg-doped indium nitride
Paper 7937-33 of Conference 7937
Date: Monday, 24 January 2011
Time: 3:40 PM 4:05 PM
Author(s): Hyeyoung Ahn, Chi-Chang Hong, National Chiao Tung Univ. (Taiwan);
Yu-Liang Hong, Shangir Gwo, National Tsing Hua Univ. (Taiwan)
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Terahertz emission from Mg-doped InN is strongly influenced by the carrier
density in such a way that the strong terahertz emission (×500 than that of
undoped InN) is obtained for InN:Mg with a critical carrier density (~1×10^18
cm-3) and it decreases as the carrier density increases. Here we report that the
carrier dynamics of InN:Mg, especially the decay time constant, is also closely
dependent on the carrier density in the same way as terahertz radiation. The
spatial redistribution of carriers in diffusion and drift is found to be
responsible for the carrier recombination process as well as terahertz emission
mechanism.
Characterization of burn injuries using terahertz time-domain spectroscopy
Paper 7890-25 of Conference 7890
Date: Tuesday, 25 January 2011
Time: 9:00 AM 9:20 AM
Author(s): M. Hassan Arbab, Trevor C. Dickey, Dale P. Winebrenner, Antao Chen,
Pierre D. Mourad, Univ. of Washington (United States)
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The accuracy rates of clinical assessment techniques used in grading burn
injuries are significantly low for partial thickness burns. In this paper, we
present experimental results from terahertz characterization of burn wounds
induced on a rat model. The rats used in this work were divided into two groups
for both acute burn characterization and 72-hour survival studies. Reflection
measurements were obtained from the surface of both burn wounds as well as
normal skin using ultra short pulsed terahertz radiation. Furthermore,
spectroscopic signal processing techniques are described for interpretation of
the acquired waveform and differentiation of burn wounds.
Nonlinear holographic imaging of terahertz radiation
Paper 7917-12 of Conference 7917
Date: Tuesday, 25 January 2011
Time: 11:00 AM 11:20 AM
Author(s): Jean-Christophe Delagnes, Patrick Mounaix, Lionel Canioni, Univ.
Bordeaux 1 (France)
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We present a theoretical investigation of a non-collinear sum frequency
generation in an electrooptic crystal between a visible and a THz radiation.
This results in the encoding of the spatial phase of the THz object field onto
the visible wave. We can thus record THz scene with conventional optical
detector that are much more sensitive than THz sensors. We show that a Nonlinear
Snell-Descartes' Lens Formula can be derived from our analysis; in comparison to
the classical one this generalized lens formula exhibits an additional
magnification factor proportional to the ratio between the optical and THz
wavelength.
Investigation of metamaterials for terahertz frequency range
Paper 7917-13 of Conference 7917
Date: Tuesday, 25 January 2011
Time: 11:20 AM 11:40 AM
Author(s): Riad Yahiaoui, Univ. Bordeaux 1 (France); Hynek Nemec, Petr Kuel,
Filip Kadlec, Christelle Kadlec, Institute of Physics of the ASCR, v.v.i. (Czech
Republic); Jörg Schilling, Martin-Luther-Univ. Halle-Wittenberg (Germany); M.
Bari, Science and Technology Research Partners Ltd. (Ireland); Jean-Christophe
Delagnes, Patrick Mounaix, Univ. Bordeaux 1 (France)
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We have demonstrated theoretical and experimental investigation of fishnet
metamaterials at terahertz frequencies. Several prototypes were fabricated using
optical lithography or laser micromachining technique. We carried out
experiments using terahertz time domain spectroscopy THz-TDS. Moreover, we
proposed THz metamaterials showing a tunable spectral interval where the
magnetic permeability reaches negative values. This behavior was confirmed both
theoretically and experimentally. These demonstrated principles represent a step
forward towards a construction of a metamaterial with negative refractive index
capable to cover continuously a broad range of THz frequencies and opens a new
path for the active manipulation of submillimeter beams.
High-temperature performance and broad continuous tunability of terahertz
quantum-cascade lasers
Paper 7953-23 of Conference 7953
Date: Tuesday, 25 January 2011
Time: 1:30 PM 2:00 PM
Author(s): Sushil Kumar, Lehigh Univ. (United States); Qi Qin, Chun W. I. Chan,
Qing Hu, Massachusetts Institute of Technology (United States); John L. Reno,
Sandia National Labs. (United States)
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We demonstrate a terahertz quantum-cascade laser (QCL) operating significantly
above the temperature of hw/kB, which has so-far been an empirical limitation
for such devices. A 1.8 THz QCL operating up to a temperature of 1.9hw/kB (163K)
is realized, with more than 3mW of peak optical power output at 150K. We also
demonstrate broadly tunable terahertz QCLs. Discontinuous tuning over a range of
165GHz is realized for a 4.4THz QCL using an antireflection-coated silicon lens
to reduce facet reflection and as a beam-forming element, with an external
grating providing frequency selective optical feedback. We have also realized
continuous tuning of 137GHz for a 3.8THz QCL with a unique concept of altering
the lateral mode profile of terahertz "wire-lasers" to achieve broad tuning.
Broadband emission from THz quantum cascade lasers
Paper 7953-24 of Conference 7953
Date: Tuesday, 25 January 2011
Time: 2:00 PM 2:20 PM
Author(s): Dana Turcinkova, Giacomo Scalari, Maria Amanti, Mattias Beck, Jerome
Faist, ETH Zurich (Switzerland)
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We demonstrate broadband laser emission at THz frequencies from quantum cascade
laser structures based on heterogenous cascades. The active material is composed
by five stacks of three different active regions. Each active region is based on
a 4-quantum well structure employing a bound-to-continuum transition. Laser
emission is observed over a bandwidth of nearly one THz, spanning from 2.24 THz
to 3.2 THz. Peak powers of more than 2 mW from a double metal waveguide and
maximum operating temperatures of 100 K have been observed with threshold
current densities as low as 230 A/cm^2 at 10 K.
Terahertz quantum cascade lasers with designer plasmonic collimators
Paper 7953-25 of Conference 7953
Date: Tuesday, 25 January 2011
Time: 2:20 PM 2:50 PM
Author(s): Nanfang Yu, Harvard Univ. (United States); Qi Jie Wang, Nanyang
Technological Univ. (Singapore); Mikhail A. Kats, Jonathan A. Fan, Harvard Univ.
(United States); Suraj P. Khanna, Lianhe Li, Alexander G. Davies, Edmund H.
Linfield, Univ. of Leeds (United Kingdom); Federico Capasso, Harvard Univ.
(United States)
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We explain how semiconductor microstructures can effectively tailor the
dispersion properties of surface plasmon polaritons in the terahertz frequency
range. The physical principles of three structures are discussed; these are
plasmonic Bragg gratings, spoof surface plasmon polariton structures, and
channel polariton structures. We demonstrate their effectiveness by solving
critical problems associated with terahertz quantum cascade lasers. By
integrating plasmonic collimators directly on the semiconductor laser facets,
the device power throughput is improved and the beam divergence is reduced by
more than one order of magnitude to ~10 degrees. We achieve these improvements
without compromising high temperature performance of the lasers.
Terahertz generation with tilted-front laser pulses: dynamical theory
Paper 7917-18 of Conference 7917
Date: Tuesday, 25 January 2011
Time: 2:40 PM 3:00 PM
Author(s): Michael I. Bakunov, Univ. of Nizhny Novgorod (Russian Federation);
Sergey B. Bodrov, Institute of Applied Physics (Russian Federation); Eugene
Mashkovich, Univ. of Nizhny Novgorod (Russian Federation)
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A theory of terahertz emission from a femtosecond laser pulse with tilted
intensity front propagating through a prism-shaped electro-optic crystal is
developed. The theory accounts for transient effects at the entrance boundary of
the crystal and allows one to explore the dynamics of terahertz generation in
the crystal. Typical experimental situations - LiNbO3 excited with Ti:sapphire
laser at room and cryogenic temperatures - are considered, and new schemes -
GaAs excited at 1.8 and 3.5 um - are proposed and analyzed. The parameters of
the laser pulse (transverse size, tilt angle, and pulse duration) and crystal
size maximizing the terahertz yield are calculated.
Optical pump-terahertz probe studies of AlGaN
Paper 7939-42 of Conference 7939
Date: Tuesday, 25 January 2011
Time: 5:00 PM 5:20 PM
Author(s): Timothy M. Sweeney, Univ. of Oregon (United States); Grace D.
Metcalfe, Gregory A. Garrett, Anand V. Sampath, Paul H. Shen, U.S. Army Research
Lab. (United States); Hailin Wang, Univ. of Oregon (United States); Michael
Wraback, U.S. Army Research Lab. (United States)
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We report on ultrafast optical pump and terahertz probe studies of free-carrier
dynamics in AlGaN materials grown with and without nano-scale compositional
inhomogeneities (NCI). We observe an initial fast decrease of the transmitted
THz signal in both AlGaN samples due to the generation of photoexcited
free-carriers. The NCI AlGaN material shows a subsequent fast decrease in THz
absorption, as compared to the NCI-free AlGaN. The faster decay time in the NCI
AlGaN sample could be due to the transfer of free-carriers into NCI states from
the AlGaN matrix as well as exciton formation and carrier recombination.
Low-threshold, quasi-cw terahertz parametric amplification in an external ring
cavity with an MgO:LiNbO3 Crystal
Paper 7917-61 of Conference 7917
Date: Tuesday, 25 January 2011
Time: 6:00 PM
Author(s): Shingo Maeda, Tatsuya Ohira, Yuma Takida, Hiroshi Kumagai, Shigeki
Nashima, Osaka City Univ. (Japan)
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We developed a terahertz parametric amplifier with an MgO-doped LiNbO3 (MgO: LN)
nonlinear crystal in an external ring cavity with the enhancement of pump power.
Moreover, the generated idler light was recycled by 2 additional flat mirrors so
as to provide a contribution to parametric amplification. As a result, we
obtained terahertz wave radiation at high-repetition of 80MHz. We additionally
examined seed injection, which seed was provided a continuous-wave diode laser
along the generated idler. In this presentation, we will show you the seed
injection experimental results together with the effect of terahertz parametric
amplification.
Novel terahertz emission devices based on efficient optical frequency conversion
in GaAs/AlAs coupled multilayer cavity structures on high-index substrates
Paper 7937-52 of Conference 7937
Date: Wednesday, 26 January 2011
Time: 8:00 AM 8:25 AM
Author(s): Takahiro Kitada, Fumiya Tanaka, Tomoya Takahashi, Ken Morita, Toshiro
Isu, Univ. of Tokushima (Japan)
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GaAs/AlAs coupled multilayer cavity structures have been proposed as novel
terahertz emission devices. Two cavity modes with an optical frequency
difference in the terahertz region are realized when two cavity layers are
coupled by an intermediate distributed Bragg reflector multilayer. Interference
between the enhanced light fields of the cavity modes was demonstrated by using
an ultrashort pulse laser. We also demonstrated extremely strong sum frequency
generation in the (113)B coupled multilayer cavity. Such coupled multilayer
cavity structures are promising for use as compact and room temperature operable
terahertz emission devices based on difference frequency generation by the
cavity-mode lights.
Novel concept for long-haul ultrashort pulse fiber delivery without pre-chirping
Paper 7912-41 of Conference 7912
Date: Wednesday, 26 January 2011
Time: 8:20 AM 8:40 AM
Author(s): Tuan Le, Gabriel Tempea, Andreas Stingl, FEMTOLASERS Produktions GmbH
(Austria); Kim G. Jespersen, OFS Fitel Denmark ApS (Denmark); Karin Wiesauer,
RECENDT GmbH (Austria)
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Ultrashort pulse fiber delivery for Ti:Sapphire lasers is basically restricted
to distances below several meters which is due to the application of dispersion
compensating devices that are not capable managing third and higher order
material dispersion. By the use of a novel fiber delivery concept ultrashort
laser pulses in the 800 nm wavelength range can now be transmitted over tens of
meters without the need for any pulse pre-compression. For the first time a
long-haul fiber delivery module will be demonstrated revealing its potential for
remote imaging or THz spectroscopy with femtosecond laser pulses.
Ultrafast carrier and phonon dynamics in graphene: relaxation, recombination,
and transport
Paper 7937-61 of Conference 7937
Date: Wednesday, 26 January 2011
Time: 1:25 PM 1:50 PM
Author(s): Farhan Rana, Haining Wang, Jared H. Strait, Cornell Univ. (United
States)
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In this talk we discuss our experimental and theoretical results on the
ultrafast dynamics of carriers and phonons in graphene. Ultrafast optical and
terahertz spectroscopy results show that photoexcited carriers in graphene
exhibit multiple time scales while undergoing relaxation and recombination
dynamics. Hot carriers lose most of their energy to optical phonons within few
hundred femtoseconds resulting in a hot phonon population which then becomes the
main bottleneck for carrier cooling. Hot optical phonons decay into acoustic
phonons via anharmonic processes within a few picoseconds. We will discuss the
relevance of our experimental and theoretical results to graphene based
optoelectronics.
Some aspects of far infrared spectroscopy of explosive materials
Paper 7938-19 of Conference 7938
Date: Wednesday, 26 January 2011
Time: 6:00 PM
Author(s): Norbert Palka, Mieczyslaw Szustakowski, Tomasz Trzcinski, Military
Univ. of Technology (Poland)
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This paper presents some potentially interesting aspects of spectroscopic
measurements of explosive materials in Far-Infrared (Terahertz) range:
preparation of the samples, influence of grain size of particles inside the
sample, influence of covering by clothes and influence of phlegmatization of
explosives - addition an agent to an explosive material to stabilize or
desensitize it. Moreover, two commonly used techniques - Far Infrared Fourier
Spectroscopy and Time Domain Spectroscopy are presented and compared.
New experimental methods in terahertz spectroscopy
Paper 7938-2 of Conference 7938
Date: Thursday, 27 January 2011
Time: 8:30 AM 8:50 AM
Author(s): Elizabeth J. Slingerland, Robert H. Giles, Thomas M. Goyette, Univ.
of Massachusetts Lowell (United States)
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Spectroscopic studies are useful in a range of areas, from remote sensing and
radio astronomy to the medical community, as spectroscopy can provide
information used to identify chemicals. New techniques have been developed for
high-resolution measurements of chemical absorption frequencies. These
high-resolution measurements not only enhance accuracy of the molecule's energy
level transitions, but also allow for environmental information to be gathered
through the collisional broadening of the spectral lines. High-resolution
measurements, made possible by far-infrared lasers coupled with Schottky diodes,
were supplemented with data taken by variable pathlength FTIR measurements in
the terahertz region. Chemicals investigated include methanol, nitric acid, and
water vapor.
Encoding terahertz signatures into laser-induced plasma acoustic waves
Paper 7938-3 of Conference 7938
Date: Thursday, 27 January 2011
Time: 8:50 AM 9:10 AM
Author(s): Benjamin W. Clough, Jingle Liu, Xi-Cheng Zhang, Rensselaer
Polytechnic Institute (United States)
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The enhancement of acoustic waves, from audible into the ultrasonic range, is a
linear function of the THz intensity incident on a laser-induced plasma, making
THz-enhanced acoustics (TEA) useful for THz detection. By using a dual-color
laser field to produce the plasma detector, THz spectroscopic information can be
encoded into the acoustic emission, making it possible to obtain the electric
field profile of the THz pulse by simply "listening" to the plasma at a
distance.
Efficient material parameters estimation with terahertz time domain spectroscopy
Paper 7938-4 of Conference 7938
Date: Thursday, 27 January 2011
Time: 9:10 AM 9:30 AM
Author(s): Osman S. Ahmed, Mohamed A. Swillam, Mohamed H. Bakr, Xun Li, McMaster
Univ. (Canada)
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We propose a novel optimization technique for the estimation of material
refractive index in the terahertz frequency range. The algorithm is applied for
materials with arbitrary frequency dependence. Dispersive dielectric models are
embedded for accurate parameter extraction of a sample with unknown thickness.
Instead of solving N expensive nonlinear optimization problems with different
possible material thickness, our technique obtains the optimal material
thickness by solving only one optimization problem. Our approach has been
successfully illustrated through a number of examples with different dispersive
models. The examples include the characterization of doped semiconductors used
in surface plasmon plaritons in the THz regime.
Terahertz imaging in dielectric media with quasi-Bessel beams
Paper 7938-5 of Conference 7938
Date: Thursday, 27 January 2011
Time: 9:30 AM 9:50 AM
Author(s): Takashi Buma, Zhuopeng Zhang, Univ. of Delaware (United States)
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We demonstrate time-domain terahertz imaging with quasi-Bessel beams created
with an axicon lens. Experiments with a high density polyethylene axicon confirm
that spatial resolution is maintained over a large depth of field. We also
demonstrate that quasi-Bessel beams experience reduced spherical aberration when
imaging objects embedded in a thick dielectric medium. Metallic objects covered
with a 12.5 mm thick plastic slab are imaged clearly with an axicon lens, while
an off-axis parabola produces poor image quality. These promising results
suggest that Bessel beams are well suited for terahertz nondestructive imaging
of thick dielectric objects.
The effects of various approximations on electron-electron scattering
calculations in QCLs
Paper 7938-7 of Conference 7938
Date: Thursday, 27 January 2011
Time: 11:00 AM 11:20 AM
Author(s): Philip Slingerland, Christopher S. Baird, Robert H. Giles, Univ. of
Massachusetts Lowell (United States)
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Electron-electron scattering is an essential mechanism involved in electron
transport in quantum cascade lasers (QCL's). However, approximations are often
made in finding the electron-electron scattering rate in order to simplify
calculations. Results will be presented characterizing various effects which are
sometimes ignored in calculating electron-electron scattering rates. These
effects include state-blocking, electron screening, temperature dependence, as
well as the inclusion of all possible transitions that can occur in three
periods of the QCL active region. These effects will be presented in the context
of several QCL active region designs.
Semiconductor-coated deep subwavelength spoof surface plasmonic waveguide for
THz and MIR applications
Paper 7938-8 of Conference 7938
Date: Thursday, 27 January 2011
Time: 11:20 AM 11:40 AM
Author(s): Ruoxi Yang, Wangshi Zhao, Zhaolin Lu, Rochester Institute of
Technology (United States)
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We propose integrated waveguides for terahertz (THz) and mid-infrared (MIR)
applications on wafer platform. Based on the prototype of spoof plasmonic
waveguides consisting of textured metallic surface, we explore the possibility
of coating periodic metallic pattern with silicon (at 0.6 THz) or germanium (at
MIR region of 30 THz) to further shrink the relative mode size of propagation
spoof plasmonic waves. Numerical modeling via 3D finite-difference time-domain
(FDTD) has shown deep sub-wavelength mode confinement in transverse directions
to smaller than ?/50 by ?/50, with an estimated propagation loss of less than
0.1 dB for each repetitive unit.
Optical frequency conductance model of teraHertz/infrared emission and detection
in quantum wells, quantum dots, and narrow-gap semiconductors
Paper 7938-9 of Conference 7938
Date: Thursday, 27 January 2011
Time: 11:40 AM 12:00 PM
Author(s): Thomas Szkopek, Elizabeth Ledwosinska, McGill Univ. (Canada)
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The optical frequency conductance is derived for quantum wells and quantum dots,
and the optical frequency conductivity of bulk narrow-gap semiconductors is
revisited. The teraHertz (THz) and infrared (IR) response of these structures,
in free-space and guided-wave geometries, is simply described within the optical
frequency conductance formalism. The fine structure constant of quantum
electrodynamics sets the natural scale for the optical conductance of
semiconductor structures. Rules of thumb and physical limits to THz/IR gain and
absorption can be derived. The optical conductance formalism is applied to MCT
photodetectors, quantum well IR photodetectors, quantum dot IR photodetectors,
and quantum cascade lasers.
A mechanically tunable terahertz modulator based on antiresonant reflecting
hollow waveguide
Paper 7938-11 of Conference 7938
Date: Thursday, 27 January 2011
Time: 1:50 PM 2:10 PM
Author(s): JaYu Lu, Hao-Zai Chen, National Cheng Kung Univ. (Taiwan); Chih-Hsien
Lai, Hung-Chun Chang, National Taiwan Univ. (Taiwan); Borwen You, National Cheng
Kung Univ. (Taiwan); Tze-An Liu, Jin-Long Peng, Industrial Technology Research
Institute (Taiwan)
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We have experimentally demonstrated a broadband tunable terahertz (THz)
modulator based on one-dimensional anti-resonant reflecting hollow waveguide
(ARRHW), which consisting of a PMMA-made cladding and a pair of
motorize-controlled metal plates located outside that. By continually varying
the distance d between the PMMA-cladding and the metal plate, it enables
dynamical tuning of the transmission band and linear attenuation of THz power
for a specific frequency. The measured maximum spectrum tuning range of 60GHz
and the power modulating depth of 20dB are achieved. The low loss THz-ARRHW
based device is also promising for the polarization filter application with
extinction-ratio of 20dB.
THz thermal emission from a 1D photonic crystal
Paper 7938-12 of Conference 7938
Date: Thursday, 27 January 2011
Time: 2:10 PM 2:30 PM
Author(s): Ian A. Zimmerman, Ziran Wu, Hao Xin, Richard W. Ziolkowski, The Univ.
of Arizona (United States)
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We have experimentally and theoretically investigated a simple 1D, bi-layered
electromagnetic crystal structure composed of air and silicon slabs. We have
calculated the emissivity using Kirchhoff's thermal radiation law, as well as by
calculating the density of states directly, and have compared those results to
the experimental values. Our ultimate goal is to be able to control the spectral
emission of an electromagnetic crystal in the THz region (or other wavelength
ranges, such as the infrared) by engineering its band structure with the desire
to develop a cheap, incoherent broadband THz source.
Applications of holography in the millimeter-wave and terahertz region
Paper 7938-15 of Conference 7938
Date: Thursday, 27 January 2011
Time: 3:40 PM 4:00 PM
Author(s): Ian McAuley, Ronan J. Mahon, J. Anthony Murphy, National Univ. of
Ireland, Maynooth (Ireland)
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In this paper we report on the holographic techniques developed for applications
in a number of areas of interest in the millimeter-wave and terahertz range. An
experimental arrangement based on off-axis near-field holography configurations
was adapted to digitally record the holograms using two radiating horn antennas
fed by a single coherent source to produce the object and reference beams. Among
the applications investigated was the measurement of the phase centres of
non-standard radiating antennas (such as a planar lens antenna). Using phase
retrieval methods, the recorded holographic interference pattern can be used to
determine the effective phase centres by numerically propagating the recovered
object beam back towards the source plane.
Electromagnetic crystal (EMXT) based THz components
Paper 7938-16 of Conference 7938
Date: Thursday, 27 January 2011
Time: 4:00 PM 4:20 PM
Author(s): Ziran Wu, Wei-Ren Ng, Michael E. Gehm, Hao Xin, The Univ. of Arizona
(United States)
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All-dielectric Terahertz waveguides based on hollow-core EMXT fiber are
fabricated via THz rapid prototyping using polymer jetting technique. Several
waveguides of identical cross-section and differing lengths are characterized by
THz time-domain spectroscopy (THz-TDS) to extract the waveguide intrinsic
propagation loss. Measurement results agree very well with simulation. This as
an initial example demonstrates a waveguide with low propagation loss of 0.03
dB/mm at 105 GHz. Based on the waveguide, an EMXT antenna is also formed by
modifying the defect shape into a horn. Simulation shows good performance of
this horn antenna. The antenna is fabricated by the same rapid prototyping
method, and its far-field pattern measurement result will be reported.
Integrated Terahertz pulse generation and amplification in quantum cascade
lasers
Paper 7945-11 of Conference 7945
Date: Sunday, 23 January 2011
Time: 11:20 AM 11:40 AM
Author(s): Sukhdeep S. Dhillon, Simon Sawallich, Nathan Jukam, Dimitri Oustinov,
Julien Madeo, Rakchanok Rungsawang, Ecole Normale Supérieure (France); Stefano
Barbieri, Pascal G. Filloux, Carlo Sirtori, Univ. Paris 7-Denis Diderot
(France); Xavier Marcadet, Alcatel-Thales III-V Lab. (France); Jerome Tignon,
Ecole Normale Supérieure (France)
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We demonstrate an integrated approach to generate and amplify Terahertz (THz)
pulses within a quantum cascade laser (QCL). Using an ultrafast interband
excitation of a THz QCL, THz pulses are generated via charge carrier
acceleration within the QCL miniband. The generated pulses are subsequently
amplified at the QCL gain as they propagate through the laser cavity. As well as
integrating the generation and amplification of THz pulses, this technique can
potentially permit efficient THz pulse injection into sub-wavelength double
metal resonators.
Circuit, antenna-based, and photonic crystal terahertz quantum cascade lasers
Paper 7945-15 of Conference 7945
Date: Sunday, 23 January 2011
Time: 1:35 PM 1:55 PM
Author(s): Jerome Faist, Christophe Walther, Maria Amanti, Giacomo Scalari,
Mattias Beck, ETH Zurich (Switzerland); Hua Zhang, Romuald Houdre, Ecole
Polytechnique Fédérale de Lausanne (Switzerland)
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In the Terahertz, MBE-grown structures have demonstrated record low frequency
operation, down to 1.2THz. Taking advantage of the tight confinement provided by
the metal-metal waveguide, we also have explored third order photonic wire
lasers as well as photonic crystal quantum cascade lasers. In a further
development, LC resonator cavities enable us to explore the coupling between
transport and photon emission in the regime of very subwavelength emitters, as
the ratio of volume over lambda cube is much below unity.
Progress in medical applications of terahertz technology in the head and neck
Paper 7883C-176 of Conference 7883C
Date: Sunday, 23 January 2011
Time: 2:40 PM 3:00 PM
Author(s): Vincent P. Wallace, The Univ. of Western Australia (Australia)
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Subpicosecond Sub-terahertz soliton laser based on a C-MOS compatible integrated
microring resonator
Paper 7945-37 of Conference 7945
Date: Monday, 24 January 2011
Time: 9:55 AM 10:10 AM
Author(s): Marco Peccianti, Institut National de la Recherche Scientifique
(Canada) and Institute for Chemical and Physical Processes (Italy); Alessia
Pasquazi, Yongwoo Park, Institut National de la Recherche Scientifique (Canada);
Brent Little, Sai-Tak Chu, Infinera Corp. (United States); David J. Moss, Univ.
of Sydney (Australia); Roberto Morandotti, Institut National de la Recherche
Scientifique (Canada)
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We present a novel subpicosecond, Sub THz -repetition rate, passively
mode-locked laser scheme based on high-harmonic four wave mixing in an
integrated CMOS-compatible high-Q nonlinear ring resonator.
Phase-locking and synthesis of terahertz quantum cascade laser emission
Paper 7953-26 of Conference 7953
Date: Tuesday, 25 January 2011
Time: 3:30 PM 4:00 PM
Author(s): Stefano Barbieri, Marco Ravaro, Pierre Gellie, Univ. Paris 7-Denis
Diderot (France); Giorgio Santarelli, LNE-SYRTE, CNRS, UPMC (France); Christophe
Manquest, Carlo Sirtori, Univ. Paris 7-Denis Diderot (France); Suraj P. Khanna,
Edmund H. Linfield, Univ. of Leeds (United Kingdom)
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We demonstrate that the carrier frequency and the repetition rate of a Terahertz
(THz) quantum cascade laser (QCL) can be simultaneously phase-locked to the
repetition rate of a mode-locked Er-fiber laser. By combining the two
stabilization techniques we show that all the longitudinal modes of a multimode
QCL emitting at ~2.4THz can be phase-locked, paving the way to the use of these
sources for high power, direct THz frequency synthesis.
Upper limits on terahertz difference frequency generation power in quantum well
heterostructures
Paper 7953-29 of Conference 7953
Date: Tuesday, 25 January 2011
Time: 4:50 PM 5:10 PM
Author(s): Yong-Hee Cho, Texas A&M Univ. (United States); Mikhail A. Belkin, The
Univ. of Texas at Austin (United States); Alexey A. Belyanin, Texas A&M Univ.
(United States)
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We investigate the upper limits on the terahertz (THz) difference frequency
generation (DFG) power that can be achieved in intersubband quantum well systems
under external mid-infrared pumping. We solve self-consistently three coupled
wave equations, the Poisson equation, and density matrix equations including
pump depletions and nonlinear saturation effects. The maximal THz DFG power is
reached for intermediate pump intensities of the order of the saturation
intensity. Further increase of pump intensities degrades the maximum THz DFG
power and shifts it to large detunings. We compare our results with recent
experiments in GaInAs/AlInAs heterostructures and suggest optimal device
designs.
Course: Terahertz Wave Technology and Applications
Date: Wednesday, 26 January 2011
Time: 8:30 AM 12:30 PM
Instructor(s): Xi-Cheng Zhang, Rensselaer Polytechnic Institute (United States)
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A pulsed terahertz (THz) wave with a frequency range from 0.1 THz to 10 THz is
called a "T-ray." T-rays occupy a large portion of the electromagnetic spectrum
between the infrared and microwave bands. However, compared to the relatively
well-developed science and technology in the microwave, optical, and x-ray
frequencies for defense and commercial applications, basic research, new
initiatives and advanced technology developments in the THz band are very
limited and remain unexplored. However, just as one can use visible light to
create a photograph, radio waves to transmit music and speech, microwave
radiation (MRI) or X-rays to reveal broken bones, T-ray can be used to create
images or communicate information. This course will provide the fundamentals of
free-space THz optoelectronics. We will cover the basic concepts of generation,
detection, propagation, and applications of the T-rays, and how the up-to-date
research results apply to industry. The free-space T-ray optoelectronic
detection system, which uses photoconductive antennas or electro-optic crystals,
provides diffraction-limited spatial resolution, femtosecond temporal
resolution, DC-THz spectral bandwidth and mV/cm field sensitivity. Examples of
homeland security and defense related projects will be highlighted.
Ultrafast terahertz spectroscopy of few-layer graphene
Paper 7937-64 of Conference 7937
Date: Wednesday, 26 January 2011
Time: 2:40 PM 3:05 PM
Author(s): Hyunyong Choi, Ferenc Borondics, David A. Siegel, Shuyun Zhou,
Michael C. Martin, Alessandra Lanzara, Robert A. Kaindl, Lawrence Berkeley
National Lab. (United States)
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Graphene is attracting significant interest due to the unique physics of its 2D
charge carriers in a linear electronic bandstructure, and due to possible
applications in e.g. high-speed electronics. Here, we discuss the broadband
optical conductivity and ultrafast THz dynamics of graphene in the few-layer
limit. The equilibrium optical response in epitaxial graphene is consistent with
the electrodynamics of a dense Dirac electron plasma, arising from highly-doped
layers at the graphene-substrate interface. We will further discuss the
transient THz response, which reflects the recombination dynamics and unusual
Drude response of graphene and its dependence on the carrier distribution
function.
Terahertz holographic interferometry
Paper 7957-42 of Conference 7957
Date: Wednesday, 26 January 2011
Time: 6:00 PM
Author(s): Andrei A. Gorodetsky, Victor G. Bespalov, Saint-Petersburg State
Univ. of Information Technologies, Mechanics and Optics (Russian Federation)
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We present our new modeling and research results on terahertz holographic
interferometry, a technique allowing to reconstruct changes in inner dielectric
object structure. The technique is somehow alike the corresponding one in
optics, but allows managing optically opaque objects. Using the broadband pulse
THz radiation with a spectrum in the range of 0.1-2.5 THz we can reconstruct
object deformations up to several microns in the bulk 3d object.
Terahertz time-lapse video of hydration in physiological tissues
Paper 7938-20 of Conference 7938
Date: Thursday, 27 January 2011
Time: 10:10 AM 10:30 AM
Author(s): David B. Bennett, Zachary D. Taylor, Sijun Sung, Borokh Makkabi,
Priyamvada Tewari, Neha Bajwa, Rahul S. Singh, Martin O. Culjat, Warren S.
Grundfest M.D., Univ. of California, Los Angeles (United States); Elliott R.
Brown, Univ. of California, Santa Barbara (United States) and Wright State Univ.
(United States)
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This study describes terahertz (THz) imaging and monitoring of physiological
tissues over long periods of time based on high sensitivity to hydration levels.
A fast-scanning, gated time-domain THz imaging system (centered at 525 GHz; 125
GHz bandwidth) was utilized which uses dynamic pixel acquisition to image a
4-cm2 area in less than two minutes. THz video was taken on three sample
systems: (1) a simple binary system of water absorbed into a polypropylene
towel, (2) the accumulation of fluid to the site of a sulfuric acid burn on ex
vivo porcine skin, and (3) the evaporative dehydration of a porcine cornea. The
diffusion-regulating behavior of corneal and skin tissue is elucidated. We
conclude from this study that THz imaging can discern the differences between
diffusion of liquid water in physiological tissues and that of inanimate,
homogeneously-diffusing matter.
Room temperature Nb5N6 microbolometer for detecting signals at terahertz region
Paper 7938-13 of Conference 7938
Date: Thursday, 27 January 2011
Time: 2:30 PM 2:50 PM
Author(s): Lin Kang, Xuchou Tu, Jian Chen, Peiheng Wu, Nanjing Univ. (China)
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Onto a double layer, which is made of a Si substrate ( ?> 1000 ?cm ) and a SiO2
layer 100 nm thick on top of it, a Nb5N6 thin film microbridge is deposited and
integrated with an dipole planar antenna. With a SiO2 air-bridge further
fabricated underneath the microbridge and operated at room temperature, such a
combination behaves very well as a microbolometer for detecting signals at 210
GHz, thanks to a temperature coefficient of resistance (TCR) as high as -0.7%
K-1 of the Nb5N6 thin film. According to our measurements and estimations, the
best attainable electrical responsivity and the response bandwidth of Nb5N6
microbolometer are about -530 V/W and 21 GHz respectively, at a current bias of
0.35 mA . The electrical noise equivalent power (NEP) is 8.27×10-12 W/Hz1/2 for
the modulation frequency above 600 Hz. A quasi-optical receiver based on such a
bolometer is constructed and measured.
Terahertz antiresonant reflecting hollow-core waveguides for sensing
applications
Paper 7938-18 of Conference 7938
Date: Thursday, 27 January 2011
Time: 4:40 PM 5:00 PM
Author(s): Borwen You, Ja-Yu Lu, National Cheng Kung Univ. (Taiwan); Chi-Yu
Chan, Chin-Ping Yu, National Sun Yat-Sen Univ. (Taiwan); Hao-Zai Chen, National
Cheng Kung Univ. (Taiwan); Tze-An Liu, Jin-Long Peng, Industrial Technology
Research Institute (Taiwan)
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A dielectric hollow tube utilized as a terahertz antiresonant reflecting
hollow-core waveguide (THz-ARRHW) sensor has been demonstrated to detect the
minute variation of both refractive index and thickness in macromolecule layers
deposited on the tube wall, and to identify liquid vapors from the various core
indices. The minimum detectable variations of sample-quantity and concentration
are down to 1.2picomole/mm^2 and 0.2%, corresponding to the variation of
2.9ตm-thickness and 0.001-refractive-index, respectively. A THz-ARRHW sensor is
also used to identify various volatile liquid vapors in the hollow-core based on
different induced core indices, and the detectable vapor density is down to
0.0001g/cm^3.
Rigorous characterization of surface plasmon modes by using the finite element
method
Paper 7941-34 of Conference 7941
Date: Wednesday, 26 January 2011
Time: 8:30 AM 8:50 AM
Author(s): B. M. Azizur Rahman, Huda Tanvir, Anita Quadir, Ken Grattan, The City
Univ. (United Kingdom)
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A rigorous full vectorial finite element-based approach has been developed to
characterize a wide range of plasmonic devices, both at optical and terahertz
frequencies. Results for wave confinement in gold nanowires, air-core guides and
defect-core metal coated photonic crystal fibers and gain threshold optimization
of quantum cascaded lasers for terahertz (THz) frequencies will be presented.
Parametric generation of terahertz wave pumped by picosecond Ti:sapphire laser
with MgO-doped LiNbO3 installed in external enhancement cavity
Paper 7917-14 of Conference 7917
Date: Tuesday, 25 January 2011
Time: 11:40 AM 12:00 PM
Author(s): Yuma Takida, Shingo Maeda, Tatsuya Ohira, Hiroshi Kumagai, Shigeki
Nashima, Osaka City Univ. (Japan)
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We built an external enhancement cavity with MgO-doped LiNbO3 (MgO:LN) and then
enhanced the pump light in the cavity. Considering that the idler light
generated in MgO:LN with the different angle of about 1 degree to the pumping
light, we designed carefully the cavity in order to circulating the idler light
as well as pump light simultaneously. In the cavity, the circulated idler light
could contribute to the terahertz parametric generation induced by the next
pumping pulse. As a result, when the idler light circulating the cavity, we
demonstrated a clear enhancement of the idler intensity.
Course: Semiconductor Optoelectronic Device Fundamentals
Date: Monday, 24 January 2011
Time: 8:30 AM 5:30 PM
Instructor(s): Kurt J. Linden, Spire Corp. (United States)
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This provides a review of the basics of semiconductor materials, with primary
emphasis on their optoelectronic properties. The motion of electrons and holes
is discussed, and photon absorption and generation mechanisms are presented. The
course examines basic device structures such as quantum wells and quantum dots,
Bragg reflectors, cascade devices, distributed feedback devices, avalanching,
tunneling, and various electro-optic effects. Device operating principles are
presented, and an overview of current device applications is given. The
participants should walk away with a good understanding of semiconductor
optoelectronics covering the entire UV to terahertz spectral region, including
devices such as diode and cascade lasers, LEDs, SLEDs, VCSELs, modulators, and
photodetectors.
Challenges in octave-spanning and short free-spectral-range optical frequency
comb generation using monolithic whispering gallery mode resonators
Paper 7913-28 of Conference 7913
Date: Monday, 24 January 2011
Time: 11:50 AM 12:20 PM
Author(s): Yanne K. Chembo, Institut FEMTO-ST (France) and Jet Propulsion Lab.
(United States); Nan Yu, Jet Propulsion Lab. (United States)
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Optical frequency combs find applications in various areas of science and
technology, such as time-frequency metrology, aerospace engineering, and
ultra-low phase noise microwave and terahertz generation. A new paradigm has
recently been proposed for the generation of these combs, and it is based on the
excitation of the whispering gallery mode of an ultra-high Q monolithic
resonator through the Kerr effect. This communication will review the main
challenges that arise from this new perspective, in order to achieve the goal of
octave spanning combs whose free spectral range is the shortest possible.
One- and two-dimensional THz spectroscopy on semiconductor nanostructures
Paper 7937-32 of Conference 7937
Date: Monday, 24 January 2011
Time: 2:45 PM 3:10 PM
Author(s): Michael Woerner, Max-Born-Institut für Nichtlineare Optik und
Kurzzeitspektroskopie (Germany)
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Using our novel high field terahertz source we performed various nonlinear
experiments on semiconductor nanostructures. In one-dimensional nonlinear
propagation experiments on n-type GaAs we observed ballistic high-field
transport and THz-induced interband tunneling of electrons. Two-dimensional THz
correlation spectroscopy performed on intersubband transitions of two coupled
quantum wells shows distinct polaronic features of the intersubband transitions.
CUDA based holographic modeling software
Paper 7957-43 of Conference 7957
Date: Wednesday, 26 January 2011
Time: 6:00 PM
Author(s): Andrei A. Gorodetsky, Saint-Petersburg State Univ. of Information
Technologies, Mechanics and Optics (Russian Federation)
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We present the result of an upgrade of previously described and used
multithreaded software for modeling the process of holographic recording and
reconstruction. The software allows 2d and 3d diffraction modeling for near- and
far-field radiation of arbitrary spectral composition both for flat and 3d
objects. The sofware was successfully applied to holographic nanolithography,
terahertz pulse holography and diffraction of ultrashort optical pulses
modeling. Today, a considerable upgrade is introduced, allowing referenceless
iteration reconstruction of multiple wavelength intensity pictures and GPU
calculation functionality.
Fellows Luncheon
Date: Monday, 24 January 2011
Time: 12:00 PM 1:30 PM
Author(s):
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All Fellows of SPIE are invited to join your colleagues for an SPIE hosted
luncheon. The new SPIE Fellows attending Photonics West will be introduced and
recognized. Please join us for this informal gathering and a chance to interact
with other Fellows. Fellows planning to attend are asked to RSVP to Brent
Johnson.
Prof. Federico Capasso
School of Engineering and Applied Sciences at Harvard University
Quantum Cascade Lasers: widely tailorable light sources from the mid-infrared to
Terahertz
Quantum Cascade Lasers represent a radical departure from conventional
semiconductor lasers in that they don't rely on the bandgap for light emission.
This freedom from bandgap slavery has many far reaching implications that will
be fully explored in this talk. I will trace the path from invention to exciting
advances in the applications of these revolutionary lasers which cover the mid-
and far-ir spectrum and are broadly impacting applications ranging from
countermeasures to gas sensing and spectroscopy in a wide range of sectors. The
talk will conclude with a discussion of the ongoing commercialization.
Federico Capasso is the Robert Wallace Professor of Applied Physics at Harvard
University, which he joined in 2003 after a 27 years career at Bell Labs where
he did research, became Bell Labs Fellow and held several management positions
including Vice President for Physical Research. His research has spanned a broad
range of areas including electronics, photonics, material science,
nanotechnology and quantum electrodynamics. He pioneered the approach widely
known as band-structure engineering in the design of heterostructure materials
and devices. He is a co-inventor of the quantum cascade laser, a fundamentally
new light source, which has now been commercialized and in recent years has been
involved in fundamental studies of forces associated with quantum fluctuations
such as the Casimir force, including the first measurement of a repulsive
Casimir force. He is a member of the National Academy of Sciences, the National
Academy of Engineering, a fellow of the American Academy of Arts and Sciences
and an Honorary Member of the Franklin Institute. His awards include the King
Faisal International Prize for Science, the Berthold Leibinger Zukunftspreis
(the future prize), Julius S
Comparison of GaAs and DAST electro-optic crystals for THz time domain
spectroscopy using 1.55 ตm fiber laser pulses
Paper 7938-6 of Conference 7938
Date: Thursday, 27 January 2011
Time: 9:50 AM 10:10 AM
Author(s): Matthieu Martin, Juliette Mangeney, Paul Crozat, Univ. Paris-Sud 11
(France); Patrick Mounaix, Univ. Bordeaux 1 (France)
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We report terahertz time-domain spectroscopy system based on Er:fiber laser at
1.55 ตm wavelength that integrate an ion-irradiated In0.53Ga0.47As
photoconductive antenna as emitter and a GaAs or a DAST electro-optic sensor as
detector. Detection using GaAs crystal is performed with an electro-optic
sampling detection based on polarization rotation of optical probe beam. We have
implemented interferometric scheme to detect the phase change of optical probe
beam due to THz-induced electro-optic effect in DAST crystal since the standard
electro-optic sampling technique is not applicable to DAST crystal. The detected
bandwidth is 3 THz using GaAs crystal and reaches 5 THz using DAST crystal.
III-nitride resonant tunneling devices from growth to fabrication
Paper 7939-50 of Conference 7939
Date: Wednesday, 26 January 2011
Time: 11:30 AM 11:50 AM
Author(s): Manijeh Razeghi, Northwestern Univ. (United States)
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The resonant tunneling diodes (RTDs) with their strong negative differential
resistance (NDR) at room temperature (RT) are promising for high frequency
generation up to terahertz enabling many applications such as ultra speed
wireless communications, spectroscopy, and imaging. III-nitride materials are
emerging candidates for RTD application due to their properties such as high
peak electron velocity, saturation velocity, and thermal stability. AlN/GaN RTDs
are expected to have high peak-to-valley ratio (P/V) and performance at RT due
to large conduction band discontinuity of 2.1 eV. However, high lattice mismatch
of conventional substrate such as sapphire which leads to high dislocations
density in epilayer and requirement for precise material, thickness, and abrupt
interface control are the biggest challenges hindering nitride-based
quantum-effect device technology. In the first part of this work, we study
metal-organic chemical vapor deposition(MOCVD) of AlN/GaN RTDs. MOCVD growth
conditions are optimized to achieve smooth heterojunctions as well as abrupt
transition between nano-scale layers with a precise thickness control. Effects
of material quality on RTDs' performance are investigated by growing RTD
structures on various templates on conventional sapphire substrate. Negative
differential resistances with P/V as high as 2.2 are realized in AlN/GaN RTD
MOCVD-grown material at RT for the first time. The alternative to reduce
dislocation densities in epilayers is homoepitaxial growth on freestanding (FS)
GaN substrates. In the second part of this work, we study MOCVD of AlGaN/GaN
RTDs on polar (c-plane) and non-polar (m-plane) freestanding GaN substrates. In
this talk we compare the performance of MOCVD-grown RTDs on different
substrates.