The Femto-Second Pulse Acquisition Spectrometer is a turnkey system for femtosecond pump-probe 2-D vibrational spectroscopy or any type of pulsed measurement. In includes a host computer and LabView-based LASPEC software, which controls the components and data acquisition. All the user has to do is focus the laser energy into the entrance slit.
We fully integrate the Array with the Electronics and the Spectrometer.
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New Beacon Femtosecond
Fluoresscence Upconversion System
Tamarack C1560 femtosecond fiber laser
Pacifica THz Time Domain Spectrometer
New Hatteras femtosecond transient
absorption system
Del Mar Photonics Product brochures - Femtosecond products data sheets (zip file, 4.34 Mbytes) - Del Mar Photonics
Send us a request for standard or custom ultrafast (femtosecond) product
Pulse
strecher/compressor
Avoca SPIDER system
Buccaneer femtosecond
fiber lasers with SHG Second Harmonic Generator
Cannon Ultra-Broadband Light
Source
Cortes Cr:Forsterite
Regenerative Amplifier
Infrared
cross-correlator CCIR-800
Cross-correlator Rincon
Femtosecond Autocorrelator
IRA-3-10
Kirra Faraday Optical Isolators
Mavericks femtosecond
Cr:Forsterite laser
OAFP optical attenuator
Pearls femtosecond fiber laser
(Er-doped fiber, 1530-1565 nm)
Pismo pulse picker
Reef-M femtosecond scanning
autocorrelator for microscopy
Reef-RTD scanning
autocorrelator
Reef-SS single shot
autocorrelator
Femtosecond Second Harmonic Generator
Spectrometer ASP-100M
Spectrometer ASP-150C
Spectrometer ASP-IR
Tamarack and Buccaneer
femtosecond fiber lasers (Er-doped fiber, 1560+/- 10nm)
Teahupoo femtosecond Ti:Sapphire regenerative amplifier
Femtosecond
third harmonic generator
Tourmaline femtosecond fiber
laser (1054 nm)
Tourmaline TETA Yb
femtosecond amplified laser system
Tourmaline Yb-SS
femtosecond solid state laser system
Trestles CW Ti:Sapphire
laser
Trestles femtosecond
Ti:Sapphire laser
Trestles Finesse
femtosecond lasers system integrated with DPSS pump laser
Wedge Ti:Sapphire multipass amplifier
Optics and Photonics 2010 presentations and notes
Acoustooptical delay lines for femtosecond pulse shaping based on crystal
materials with strong acoustic anisotropy
Paper 7789-8 of Conference 7789
Date: Monday, 02 August 2010
Author(s): Vladimir Y. Molchanov, Sergey I. Chizhikov, National Univ. of Science
and Technology (Russian Federation); Oleg Y. Makarov, Molecular Technology GmbH
(Germany); Efim A. Khazanov, Vladislav N. Ginzburg, Institute of Applied Physics
(Russian Federation)
The femtosecond pulse quality in a laser system is determined by a
non-compensated high-order dispersion and spectral deformation of the amplifier.
A dispersive device that modifies the spectral amplitude and phase of the
femtosecond pulse should be used to improve the duration of the compressed pulse
and suppress the prepulses. The application of acoustoopical dispersive delay
lines is considered. Different modifications of delay lines are compared and the
types of devices used to shape femtosecond pulses are discussed. Different
experimental dispersive delay lines were fabricated and investigated.
Ablation of silicon by focusing a femtosecond laser through a subwavelength
annular aperture structure
Paper 7789-21 of Conference 7789
Date: Monday, 02 August 2010
Author(s): Yuh-Yan Yu, National Taiwan Univ. (Taiwan); Chin-Kai Chang, Ming-Wei
Lai, Industrial Technology Research Institute (Taiwan); Long-Sun Huang,
Chih-Kung Lee, National Taiwan Univ. (Taiwan)
We examined the effect of using laser energy on the ablation of silicon with a
Ti:sapphire femtosecond laser. The femtosecond laser was focused through an
oxide-metal-oxide film engraved with a subwavelength annular aperture structure
to create a quasi-Bessel beam for long depth of focus machining. The
experimental results showed that the silicon can be ablated with an extremely
low input ablation threshold, which was in the order of 0.3 J/cm2 for a pulse
duration of around 130 femtoseconds. The depth of focus and the focal spot of
the SAA structure were simulated using finite-difference time domain
calculations. The far-field laser beam which propagated through the SAA
structure possessed both a sub-micron focal spot, long depth of focus, and high
focus intensity. The results show that this kind of system has good potential
when silicon machining is required, which is particularly true for creating high
aspect ratio surface structures.
Generation of femtosecond Bessel type pulses using multi-ring circular-slit
diaphragm
Paper 7789-29 of Conference 7789
Date: Monday, 02 August 2010
Author(s): Vladimir Belyi, Svetlana N. Kurilkina, Elena Ushakova, B.I. Stepanov
Institute of Physics (Belarus)
It is shown that using a multi-ring circularly-slit diaphragm placed in focal
plane of lens, it is possible to form pulsed beams of Bessel type characterized
by a narrow central maximum and essential suppression of lateral maxima in the
radial intensity distribution. It has been established that with increasing
radius and number of diaphragm rings, the narrowing of central maximum with
accompanying essential decrease of lateral maxima takes place. When a Gaussian
pulse falls on two-ring diaphragm at a definite distance from lens, a weak
satellite is found to appear in the formed femtosecond beam. At the same time
the beam-pulse formed using three-ring diaphragm has the envelope with two
distinguished maxima, one of which decreases when moving off the lens.
Fabrication of Raman biochip prototype by femtosecond laser micromachining
Paper 7759-42 of Conference 7759
Date: Tuesday, 03 August 2010
Author(s): Zenghui Zhou, Jian Xu, Fei He, Yang Liao, Ya Cheng, Zhizhan Xu,
Shanghai Institute of Optics and Fine Mechanics (China); Koji Sugioka, Katsumi
Midorikawa, RIKEN (Japan)
A nanoscale surface-enhanced Raman scattering (SERS) substrate is fabricated by
fs laser reduction and deposition. The conductive silver microstructures are
also deposited in fs laser irradiated area on the glass surfaces. Based on this
approach, we integrate the microelectronic circuit and micro-Raman substrate
into a microfluidic chamber and form a prototype of Raman biochip for
biosensing. Enhancement of Raman signal and control of temperature of the sensor
are both achieved. This technique provides a great potential for integrating
microelectronics and micro-Raman sensors on a single glass chip.l>
Femtosecond optical Kerr gating using nonlinear photonic crystal fiber
Paper 7775-51 of Conference 7775
Date: Wednesday, 04 August 2010
Author(s): Qian Xu, Kebin Shi, Zhiwen Liu, The Pennsylvania State Univ. (United
States)
We experimentally investigated optical Kerr gating effect by co-propagating a
pump beam and a weak signal beam in a nonlinear photonic crystal fiber. It is
shown that optical Kerr gating can be observed by using femtosecond pump pulses
with only a few milliwatts of average power.
Widefield multiphoton excited fluorescence microscopy for animal study in vivo
Paper 7765-32 of Conference 7765
Date: Wednesday, 04 August 2010
Author(s): Shean-Jen Chen, Li-Chung Cheng, Chia-Yuan Chang, Hung-Wei Su,
National Cheng Kung Univ. (Taiwan)
A widefield multiphoton excited fluorescence microscope with a simultaneously
spatial and temporal focusing technique has been developed to provide fast
three-dimensional (3D) multiphoton fluorescence images fro animal study in vivo.
Unlike conventional multiphoton microscopy based on pixel by pixel scanning
technique, the wide-field multiphoton microscope only scans one dimension,
z-axis, to construct a 3D image. By using a Ti:sapphire femtosecond laser
oscillator as a seed laser for the femtosecond laser amplifier with a repetition
rate of 10 kHz, we raise the average power from 1.0 to 4.2 W, which is enough
power to excite the fluorescence in the area over 100 μm x 100 μm. The
fluorescence image signal is detected by an EM CCD, which frame rate might rise
up to 1 kHz according to the efficiency of fluorophore, so the widefield
multiphoton microscopy can provide very fast imaging fro animal study in vivo
such as monitoring brain neuron activity and liver metabolism.
Near-field imaging with a localized nonlinear light source (Keynote
Presentation) (Keynote Presentation)
Paper 7757-4 of Conference 7757
Date: Sunday, 01 August 2010
Author(s): Lukas Novotny, Stefano Palomba, Univ. of Rochester (United States)
We demonstrate high-resolution near-field imaging and spectroscopy using the
nonlinear optical response of a gold nanoparticle pair as an excitation photon
source. Femtosecond pulses of frequencies f1 and f2 are used to induce a
nonlinear polarization at the four wave mixing (4WM) frequency 2 f1 − f2 in the
junction of the nanoparticle dimer. The nonlinear response leads to localized
photon emission, which is employed as an excitation source for fluorescence and
extinction imaging. The principle of this imaging technique is demonstrated for
samples of fluorescent nanospheres and tubular J-aggregates
Tomography with random snapshots of faint non-stationary objects
Paper 7800-1 of Conference 7800
Date: Monday, 02 August 2010
Author(s): Abbas Ourmazd, Peter Schwander, Univ. of Wisconsin-Milwaukee (United
States); Dimitris Giannakis, Courant Institute of Mathematical Sciences (United
States); George N. Phillips, Jr., Univ. of Wisconsin-Madison (United States)
A new generation of powerful algorithms is poised to enable the determination of
the structure and evolution of objects ranging from single molecules to beating
hearts and breathing lungs. At one extreme, new algorithms are paving the way to
atomic-level mapping of the conformations of biological molecules with
femtosecond time resolution. At the other, they are driving ultra-low-dose
tomography of non-stationary, faintly scattering macroscopic objects. We
describe how such approaches can be used to reconstruct the structure and
conformational continuum of individual molecules, viruses, and potentially
living cells.
Supercontinuum generation using small core photonic crystal fibers
Paper 7781-21 of Conference 7781
Date: Monday, 02 August 2010
Author(s): Luiz C. Barbosa, Enver F. Chillcce, Italo O. Mazali, Univ. Estadual
de Campinas (Brazil)
In this work we study the supercontinuum generaton using small core silica
photonic crystal fibers (PCFs). The core of the PCFs varying from 1.0 to 2.0 µm
was possible changing the external fiber diameter. The PCFs have structures
which consist of small hollows. The supercontinum light, that extends from blue
to near infra-red region, was obtained using a femtosecond 785 nm Ti:Saphire
laser. The blue light generated is very intense, which could be used to
fluorescence applications as biological.
Three-dimensional polymer microdevices with gold nanorods
Paper 7757-123 of Conference 7757
Date: Monday, 02 August 2010
Author(s): Shean-Jen Chen, Wen-Shuo Kuo, Chi-Hsiang Lien, National Cheng Kung
Univ. (Taiwan)
In this study, nonlinear multiphoton photocrosslinking and photopolymerization
of rose bengal and trimethylolpropane triacrylate monomers in solution have been
used to direct the three-dimension (3D) assembly of microdevices; moreover, we
also presents the first example of containing gold nanorods within the
photopolymerization. The experimental results show that the two-photon excited
photopolymerization containing the nanorods improves more efficiently of
decreasing the power density of femtosecond laser, and also provides a great
diversity of optical properties. The doped nanorods with two-photon luminescence
act as label molecules for internal microdiagnosis of 3D polymer microdevices.
Nanojoining as interconnect and packaging technologies for nanodevices
Paper 7764-12 of Conference 7764
Date: Tuesday, 03 August 2010
Author(s): Norman Y. Zhou, Univ. of Waterloo (Canada)
Joining, whether at nano-, micro- or macro-scale, is an essential part of
man-made product manufacturing and assembly, providing mechanical coupling and
support, electrical connection or insulation, environmental protection, etc.
Nanojoining, also termed nanobonding, nanowelding, nanobrazing, nanosoldering,
etc., has attracted growing interests in the past few years as emerging
interconnect and packaging technologies for nanodevices and nanosystems. A
number of nanojoining techniques have been developed and will be described,
namely, femtosecond laser welding of Au nanoparticles, low temperature bonding
using Ag nanoparticles, and brazing of carbon nano-tubes (CNTs).
Experimental observation of the Laue diffraction in one-dimensional photonic
crystals
Paper 7755-23 of Conference 7755
Date: Wednesday, 04 August 2010
Author(s): Sergey E. Svyakhovskiy, Anton I. Maydykovskiy, Ilya E. Razdolski,
Tatiana V. Murzina, Alexander A. Skorynin, Boris I. Mantsyzov, Oleg A.
Aktsipetrov, Moscow State Univ. (Russian Federation)
Theoretically predicted that the femtosecond laser pulse propagating in the
linear photonic crystal (PC) in case of the Bragg diffraction at the Laue scheme
is separated into two, called the transmitted and the diffracted pulses. Each of
them, in turn, is separated into two pulses with different propagation velocity,
which is associated with redistribution of the field of an initial pulse between
the layers of PC. In this work we experimentally observed spatial laser pulse
splitting into two beams in a PC made of porous silicon. Direction and intensity
of transmitted and diffracted beams coincides with theoretically predicted.
Spatio-temporal control of fields around nano-antennas
Paper 7757-16 of Conference 7757
Date: Sunday, 01 August 2010
Author(s): Daan Brinks, Marta Castro Lopez, Alberto G. Curto, Richard Hildner,
Tim H. Taminiau, Niek F. van Hulst, ICFO - Instituto de Ciencias Fotónicas
(Spain)
Nano-antennas concentrate electromagnetic fields in sub-diffraction limited
hotspots, whose position in time and space depends on the antenna-structure and
the incoming electromagnetic field. Antennas can therefore be combined with
ultrafast pulses to address femtosecond processes in nanometric volumes,
provided one takes into account and compensates for the dispersion of the
antenna-structures. We adapt the field of an excitation pulse to the dispersion
and resonances of an optical gap-antenna. This way we change and enhance the
localization of hotspots, while at the same time obtaining quantitative
information about the field dynamics around the structure. Our latest
experimental results will be presented.
Two-photon spectroscopy allows for probing of the pi-conjugation pathway in
tetrapyrolles
Paper 7774-20 of Conference 7774
Date: Monday, 02 August 2010
Author(s): Nikolay S. Makarov, Mikhail Drobizhev, Montana State Univ. (United
States); Elena A. Makarova, Evgeny A. Lukyanets, Institute of Biochemistry and
Physiology of Plants and Microorganisms (Russian Federation); Aleksander K.
Rebane, Montana State Univ. (United States)
Two-dimensionally extended, branched, pi-electron structure provides
tetrapyrrolic molecules their unique optical properties, which makes them
attractive for photonics applications. The knowledge of the structure and the
symmetry of the pi-electron conjugation pathway thus presents an important task
for understanding of the optical properties of tetrapyrroles. Here we study
femtosecond two-photon absorption (2PA) and excited-state absorption spectra of
metal-free centrosymmetrical tetra-tert-butyl-phthalocyanine and formally
non-centrosymmetrical tribenzo-tetraazachlorin. We show that both molecules
contain a strong 2PA transition near 940 nm, which is absent in corresponding
one-photon absorption spectra. This observation imply, in accordance with
previous quantum-chemical calculations, that the main pi-conjugation pathway of
phthalocyanines excludes the outer parts of the pyrrolenine rings.
Ultra-fast dynamics of spin and orbital magnetic moments of CoPd alloys probed
by time resolved x-ray magnetic circular dichroism
Paper 7760-21 of Conference 7760
Date: Tuesday, 03 August 2010
Author(s): Eric Beaurepaire, Christine Boeglin, Valérie Halté, Jean-Yves Bigot,
Victor Lopez-Flores, Jacek Arabski, Institut de Physique et Chimie des Matériaux
de Strasbourg (France); Christian Stamm, Nikolaus Pontius, Hermann Dürr,
Helmholtz-Zentrum Berlin für Materialien und Energie GmbH (Germany)
Ultrashort optical laser pulses (60 fs) have been used to change the
magnetization of a ferromagnetic CoPd alloy film, and probe its dynamics with
circularly polarized femtosecond X-ray pulses (100 fs), measuring the magnetic
dichroism at Co L2,3 edges. The use of sum rules allows disentangling for the
first time, the spin and orbital components of the magnetic moment. We show that
the dynamics of L and S are different. Our results show that the mechanism
responsible for the ultrafast laser induced demagnetization requires the concept
of spin-orbit interaction, and that the magneto-crystalline anisotropy energy is
an important quantity to consider.
Role of carrier diffusion and picosecond exciton kinetics in nonproportionality
of scintillator light yield
Paper 7805-19 of Conference 7805
Date: Tuesday, 03 August 2010
Author(s): Richard T. Williams, Joel Q. Grim, Qi Li, Wake Forest Univ. (United
States); William W. Moses, Lawrence Berkeley National Lab. (United States)
Numerical modeling of carrier diffusion and drift in the strong concentration
gradient surrounding the track of an energetic electron in the
femtosecond-picosecond time domain shows that hole and electron mobilities can
exert a controlling influence on whether subsequent recombination kinetics are
1st or 2nd order, and what the effective volume density of recombinations is, as
it affects nonradiative 2nd and 3rd order decay processes. These affect the
shape of both the low- and high-dE/dx ends of the light-yield curve of a
scintillator. We report time-resolved measurements of recombination kinetics at
the high excitation densities appropriate to track ends and the picosecond
population dynamics of excitons and activators in CsI:Tl.
Non-adiabatic change in frequency of light trapped in a GaAs-AlAs microcavity
Paper 7756-13 of Conference 7756
Date: Tuesday, 03 August 2010
Author(s): Philip J. Harding, Univ. Twente (Netherlands); Huib J. Bakker, Alex
Hartsuiker, FOM Institute for Atomic and Molecular Physics (Netherlands); Julien
Claudon, Commissariat à l'Énergie Atomique (France); Allard P. Mosk, Univ.
Twente (Netherlands); Jean-Michel Gérard, Commissariat à l'Énergie Atomique
(France); Willem L. Vos, Univ. Twente (Netherlands)
We study frequency-resolved femtosecond pump-probe reflectivity of a planar
GaAs-AlAs microcavity. About 8 ps after a pump pulse, we observe a strong excess
probe reflectivity. Light trapped in the cavity accumulates a phase change due
to a time-dependent refractive index, resulting in a change in frequency by more
than 5 linewidths away from the cavity resonance. The frequency change is
non-adiabatic as the wave function changes shape in time and the rate of change
of the cavity resonance is fast. An analytical model predicts dynamics in
agreement with experiments, and points to crucial parameters that control future
applications.
Orientation determination for 3D single molecule diffraction imaging
Paper 7800-25 of Conference 7800
Date: Tuesday, 03 August 2010
Author(s): Chao Yang, Stefano Marchesini, Lawrence Berkeley National Lab.
(United States)
The latest development of ultrafast free electron laser makes it possible to
perform single molecule diffraction imaging. In such an experiment,
two-dimensional diffraction images of randomly oriented molecules of the same
type can be captured within femtosecond exposure time. To deduce the 3D
structure of the molecule at high resolution, we must solve two challenging
problems: 1) the determination of the relative orientations of 2D images; 2)
phase retrieval of a reconstructed 3D diffraction pattern. We will focus on the
first problem and discuss the use of common curve detection techniques to deduce
the relative orientation of 2D diffraction images.
Upconversion as a tool for characterization and preparation of photonic quantum
states
Paper 7815-9 of Conference 7815
Date: Wednesday, 04 August 2010
Author(s): Alfred B. U'Ren, Univ. Nacional Autónoma de México (Mexico); Kevin A.
O'Donnell, Ctr. de Investigación Científica y de Educación Superior de Ensenada
(Mexico)
There are few ways of characterizing photon wavepackets on an ultrafast
time-scale. While femtosecond resolution can be necessary, optical detectors
have a slower response by several orders of magnitude. One way of overcoming
this limitation is with Hong-Ou-Mandel interference. Another possible ultrafast
characterization method is to introduce a controlled delay between generated
signal and idler photons, overlap them spatially in a nonlinear crystal, and
detect the sum-frequency photon, in analogy to the autocorrelation of classical
laser pulses. We present experimental results where we demonstrate this latter
principle and discuss extensions of this work for the preparation of photonic
quantum states.
Dynamic complex optical fields for optical manipulation, 3D microscopy, and
photostimulation of neurotransmitters
Paper 7762-64 of Conference 7762
Date: Wednesday, 04 August 2010
Author(s): Vincent R. Daria, Christian Stricker, John Bekkers, Steve Redman,
Hans-Albert Bachor, The Australian National Univ. (Australia)
We demonstrate a multi-functional system capable of multiple-site two-photon
excitation of photo-sensitive compounds as well as transfer of optical
mechanical properties on an array of mesoscopic particles. We use holographic
projection of a single Ti:Sapphire laser operating in femtosecond pulse mode to
show that the projected three-dimensional light patterns have sufficient
spatiotemporal photon density for multi-site two-photon excitation of biological
fluorescent markers and caged neurotransmitters. Using the same laser operating
in continuous-wave mode, we can use the same light patterns for non-invasive
transfer of both linear and orbital angular momentum on a variety of mesoscopic
particles. The system also incorporates high-speed scanning using acousto-optic
modulators to rapidly render 3D images of neuron samples via two-photon
microscopy.
Fundamental understanding of the ordered heterojunction hybrid systems from in
situ polymerization for photovoltaics
Paper 7777-75 of Conference 7777
Date: Wednesday, 04 August 2010
Author(s): Tingting Xu, Xingzhong Yan, South Dakota State Univ. (United States);
Jing-Shun Huang, Ching-Fuh Lin, National Taiwan Univ. (Taiwan); David W.
Galipeau, Qiquan Qiao, South Dakota State Univ. (United States)
Ordered heterojunction hybrid systems from in-situ polymerization is one of the
promising technologies to achieve high efficiency because it has an optimized
structure to increase the exciton dissociation and charge transport. Here,
in-situ electrochemical polymerization of a polythiophene (P3HT) into vertical
aligned ZnO nanorods was prepared through a novel silane linker. Through the
UV-visible absorption measuremen, it was found that this ordered hybrid system
had a comparable absorption with the other methods including the physical
filtration of P3HT into the nanorod template. The femtosecond fluorescence
up-conversion (FFU) technique was used to probe the dynamics of vibrational
relaxation processes, intra-chain (intramolecular) and inter-chain
(intermolecular) energy transfer between segments, self-trapping of excitons,
and/or charge transfer dynamics of the in-situ polymerized hybrid system and
their application photovoltaics.
Course: Nanoplasmonics
Date: Thursday, 05 August 2010
Instructor(s): Mark I. Stockman, Georgia State Univ. (United States)
Nanooptics deals with optical phenomena and spectroscopy on the nanoscale, i.e.,
in the regions of space whose size is much smaller than the light wavelength.
While electromagnetic waves cannot be localized in the regions with sizes
significantly less than half wavelength, nanooptics is based on electric fields
oscillating at optical frequency. From the positions of the interaction with
matter and spectroscopy, such local optical fields mostly produce the same type
of responses as electromagnetic waves. Elementary excitations that are carriers
of energy and coherence in nanooptics are surface plasmons (SPs). These local
fields cause a wealth of gigantically enhanced optical phenomena of which the
surface enhanced Raman scattering (SERS) is the most studied and widely known.
This one-day course will encompass the fundamental properties and applications
of the surface plasmonics at the nanoscale. It will include coherent effects
associated with phase memory of the SPs, in particular, coherent control of
nanooptical phenomena. Nonlinear processes such as generation of harmonics and
two-photon excitation by nanoscale fields will also be covered. Ultrafast
(femtosecond and attosecond) phenomena are within the scope of this course. We
will also include quantum phenomena associated with properties of surface
plasmons as quantum quasiparticles such as quantum generation and fluctuations.
Along with fundamental properties of SPs, we will consider many applications of
nanoplasmonics, in particular, detection of ultrasmall amounts of chemical and
biological compounds, scanning near-field optical microscopes or SNOMs, and
nanolithography.
Interfacial charge transfer excitations for optical applications: A case of
molecule-metal and molecule-semiconductor nanoclusters
Paper 7758-1 of Conference 7758
Date: Wednesday, 04 August 2010
Author(s): Ramakrishna Guda, Western Michigan Univ. (United States)
Optical excitations in donor-acceptor systems in organic molecules, polymers,
nanomaterials and molecule-nanomaterial interface are under intense research
both because of their fundamental interest as well as applications in
photo-voltaics, nonlinear optics and sensors. One of the important applications
is in solar energy conversion especially the ones related to dye-sensitized
solar cells1 and organic bulk heterojunction solar cells2. These systems are
considered cost-effective alternatives to silicon based solar cells. Vital
aspect of these devices is the photo-induced electron transfer where the
photo-excited donor transfers the electron to the acceptor. Our strategy is to
use the interfacial charge transfer excitons where the excitation leads directly
to an electron on the acceptor and hole in the donor without loss as heat due to
photo-induced electron transfer3, 4. If this energy can be converted without
loss as heat, the solar cell efficiencies can be increased by as high as 5%.
Dynamics of direct charge transfer excitations in small molecule-TiO2
nanoparticles5 and chromophore functionalized TiO2, ZnO and ZrO2 nanoparticles
are investigated6. Interesting localization and delocalization of the charge
transfer excitations are observed which can provide insights in designing better
dye molecules which can improve the solar energy conversion efficiency. In
addition, chromophore-gold cluster composites are being investigated which have
shown directional photo-induced electron transfer and interfacial charge
transfer excitations. Femtosecond fluorescence upconversion and transient
measurements measurements are being utilized to follow such charge transfer
excitations and the consequent localization and delocalization pathways. Present
results also show the potential of these systems as better nonlinear optical
materials especially in relation to optical limiting. References 1. Gratzel, M
Nature 2001, 414, 338. 2. Dennler, G.; Scharber, M.; Brabec, C. J. Adv. Mater.
2009, 21, 1323. 3. Tae, E. L.; Lee, S. H.; Lee, K.; Yoo, S. S.; Kang, E. J.;
Yoon, K. B. J. Phys. Chem. B 2005, 109, 22513. 4. Schmidtke, J. P.; Friend, R.
H.; Silva, C. Phys. Rev. Lett. 2008, 100, 157401 5. Varaganti, S.; Ramakrishna,
G. J Phys Chem (submitted). 6. Varaganti,S.; Gessesse, M.; Obare, S.;
Ramakrishna, G. Proc SPIE 2009, 741309, 741309/01-10.
The role of polarization pulse shaping in ultrafast nanooptics: adaptive and
deterministic control mechanisms
Paper 7757-12 of Conference 7757
Date: Sunday, 01 August 2010
Author(s): Walter Pfeiffer, Univ. Bielefeld (Germany)
Recent theoretical investigations as well as experiments have shown that the
polarization degree of freedom of the incident light is essential to manipulate
and control nanophotonic excitations on an ultrashort time scale and at a length
scale below the diffraction limit. The present status of knowledge is reviewed
and a qualitative discussion of the different control mechanisms is presented.
To some extend deterministic rules are applicable to realize particular
nanophotonic excitations as it is shown for spatial contrast reversal.
Spaser as nanoscale optical generator and ultrafast nano-amplifier
Paper 7754-16 of Conference 7754
Date: Monday, 02 August 2010
Author(s): Mark I. Stockman, Georgia State Univ. (United States)
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. We will review
the numerous existing applications of nanoplasmonics: nanoantennas for
photovoltaic cells and LEDs, nanoplasmonic labels, tests, and sensors for
biology, medicine, industry, environmental monitoring and defense,
ultramicroscopy, plasmonics-assisted magnetic recording, nanoshell-mediated
cancer treatment, etc. From the latest developments and original work in
nanoplasmonics, we will concentrate on the SPASER as a quantum nanoscale optical
generator and ultrafast nanoamplifier of local fields.
Chalcogenide photonic integrated circuits for ultrafast nonlinear optics
Paper 7756-18 of Conference 7756
Date: Tuesday, 03 August 2010
Author(s): Benjamin J. Eggleton, The Univ. of Sydney (Australia)
This paper reviews our recent progress in developing dispersion engineered
highly nonlinear chalcogwnide circuits for all-optical processing. Highlights of
this research include recent demonstrations of >Tera/baud per second optical
switching and waveform analysis.
Pulse laser driven ultrafast micro and nanofluidics system
Paper 7759-36 of Conference 7759
Date: Tuesday, 03 August 2010
Author(s): Pei-Yu Chiou, Univ. of California, Los Angeles (United States)
A tightly focused laser beam is capable of disrupting water medium directly and
inducing localized hot plasma for rapid heating and creating cavitation bubbles.
These bubbles expand at speeds up to hundred meters per second in the micro and
nanometer scale. Through proper engineering designs, such ultrafast microfluidic
phenomena can be utilized for actuating ultrafast microfluidic devices to enable
new functionalities not possible with conventional microfluidic devices.
Electron and XUV light emission probes of ultrafast nano-localized plasmonic
fields
Paper 7757-47 of Conference 7757
Date: Wednesday, 04 August 2010
Author(s): Matthias F. Kling, Max-Planck-Institut für Quantenoptik (Germany)
Recent advantages in laser technology have paved the way for a full control of
the waveform of optical fields. The use of metallic nanostructures for
high-harmonic generation (HHG) via nanoplasmonic field enhancement offers a
route for the production of ultrashort XUV pulses. We have theoretically studied
the influence of the sub-cycle field evolution of the driving laser field on the
generated plasmonic fields and found feasible conditions for the generation of
single attosecond pulses. These results together with first experimental work on
HHG from nanostructures will be presented. We will furthermore present results
on the characterization of nanolocalized plasmonic fields utilizing
time-of-flight photoelectron emission microscopy (TOF-PEEM).
Probing ultrafast nano-localised plasmonic fields via XUV light generation
Paper 7757-48 of Conference 7757
Date: Wednesday, 04 August 2010
Author(s): Sarah L. Stebbings, Frederik Süßmann, Ying Ying Yang,
Max-Planck-Institut für Quantenoptik (Germany); Roswitha Graf, Alexander
Apolonskiy, Ludwig-Maximilians-Univ. München (Germany); Alexander
Weber-Bargioni, Lawrence Berkeley National Lab. (United States); Mark I.
Stockman, Georgia State Univ. (United States); Ferenc Krausz, Matthias F. Kling,
Max-Planck-Institut für Quantenoptik (Germany)
The use of nanostructure arrays, such as bow-tie-like antennae, offer a
promising route to ultrashort XUV pulses via plasmonic enhanced high harmonic
generation at relatively low laser intensities. By performing a systematic
theoretical investigation, the optimal conditions for the generation of single
XUV pulses via nanoplasmonic field enhancement have been identified. Both the
experimental and theoretical results of this work will be presented at the
conference.
Photodetector behavior in the presence of ultrafast laser irradiance
Paper 7780A-7 of Conference 7780A
Date: Wednesday, 04 August 2010
Author(s): Michael K. Rafailov, Richer LLC (United States)
Ultra-fast laser is able to change optical state of semiconductor. These changes
are time-dependent and completely reversible: ultra-fast laser "bleaches"
semiconductor and therefore temporally changes detector's optical
characteristics. Practically, ultra-fast laser allows remote control of
fundamental properties of semiconductor and therefore, temporal alteration of
photodetector's characteristics - such as responsivity and detectivity as well
as response time and response spectral bandwidth. However, with excessive energy
transfer that can follow bleaching the effect may be masked by thermal noise or
even lattice disorder. In this paper we will discuss some foundations of
ultra-fast laser bandgap photonics in connection to ultra-fast low energy per
pulse laser.
Electrical polaritonic control of ultrafast optical amplification in
semiconductor microcavities
Paper 7756-33 of Conference 7756
Date: Wednesday, 04 August 2010
Author(s): Jeremy J. Baumberg, Gabriel Christmann, Univ. of Cambridge (United
Kingdom); Pavlos Savvidis, Nikolaos Pelekanos, Zacharias Hatzopoulos, Simeon
Tsintzos, Univ. of Crete (Greece); Chris Coulson, Cornelius Grossman, Univ. of
Cambridge (United Kingdom)
Optical amplification in strongly-coupled semiconductor microcavities is the
largest reported for any material. We report high-speed electronic control of
ultrafast polariton amplification in an electrically-biased semiconductor
microcavity which contains double-quantum wells. A >90% reduction of the
parametric scattering gain is obtained by tuning the intracavity electric field
to turn on inter-well resonant tunneling.
Ultrafast optical switching of nematic liquid crystal birefringence
Paper 7775-47 of Conference 7775
Date: Wednesday, 04 August 2010
Author(s): Iam Choon Khoo, Justin Liou, Michael V. Stinger, The Pennsylvania
State Univ. (United States)
The theory and experimental demonstrations of ultra-fast all-optical switching
based on laser induced order parameter and birefringence changes with cw -
nanosecond pulsed lasers at 400 nm - 1550 nm will be presented.
Ultrafast transient absorption microscopy studies of carrier dynamics in
epitaxial graphene
Paper 7758-35 of Conference 7758
Date: Thursday, 05 August 2010
Author(s): Libai Huang, Gregory V. Hartland, Huili Xing, Univ. of Notre Dame
(United States)
Energy exchange between the electrons and phonons is particularly important to
electron transport, and understanding this process will be vital for the
realization of future graphene-based electronics. Epitaxial growth is a very
promising approach for practical applications, as it has the ability to prepare
graphene on a large scale and supported on a substrate. However, epitaxially
grown graphene is highly inhomogeneous, with variations in the sample thickness
occurring over length scale of a few micrometers. To pave the road for
electronic devices based on epitaxial graphene, characterization methods with
high spatial resolution are required. Here we present transient absorption
microscopy as a novel tool to characterize graphene, and to interrogate the
charge carrier dynamics. This technique has the ability to directly image
carrier dynamics with a diffraction-limited spatial resolution and a time
resolution of ~ 200 fs. The intensity of the transient absorption signal is
shown to correlate with the number of graphene layers. The carrier cooling
exhibits a bi-exponential decay, consisting of an instrument-response limited
fast decay time 1 (< 0.2 ps) and a slower decay time 2. The fast and slow
relaxation times were assigned to coupling between electrons and optical phonon
modes and the hot phonon effect, respectively. The limiting value of the slow
relaxation time at high pump intensity reflects the lifetime of the optical
phonons. The contribution of the slow component to the overall decay was found
to vary with spatial position in the sample. This is attributed to differences
in coupling between the graphene and the substrate. These results point to
transient absorption microscopy as a potentially important tool for
characterizing graphene.
Modeling of non-adiabatic photoinduced dynamics and energy transfer in
conjugated molecules
Paper 7758-6 of Conference 7758
Date: Wednesday, 04 August 2010
Author(s): Sebastian Fernandez-Alberti, Univ. Nacional de Quilmes (Argentina);
Valeria D. Kleiman, Adrian E. Roitberg, Univ. of Florida (United States); Sergei
Tretiak, Los Alamos National Lab. (United States)
Prediction and understanding of photoinduced processes in molecular- and
nano-materials is fundamental to a myriad of technological applications, ranging
from sensing, imaging, solar energy harvesting, to future optoelectronic
devices. This talk will overview several applications of recently developed
excited state molecular dynamics framework incorporating non-adiabatic quantum
transitions studying ultrafast dynamics and exciton transport in several
conjugated molecular systems. Our calculations rely on the use of the Collective
Electronic Oscillator (CEO) package accounting for many-body effects and actual
potential energy surfaces of the excited states combined with the Tully's fewest
switches algorithm for surface hopping probing non-adiabatic processes. Our
analysis show intricate details of photoinduced vibronic relaxation and identify
the conformational degrees of freedom leading to ultrafast energy transfer. This
theoretical modeling allows to understand and to potentially manipulate energy
transfer pathways in molecular materials suitable for solar energy conversion.
Upconversion as a tool for characterization and preparation of photonic quantum
states
Paper 7815-9 of Conference 7815
Date: Wednesday, 04 August 2010
Author(s): Alfred B. U'Ren, Univ. Nacional Autónoma de México (Mexico); Kevin A.
O'Donnell, Ctr. de Investigación Científica y de Educación Superior de Ensenada
(Mexico)
There are few ways of characterizing photon wavepackets on an ultrafast
time-scale. While femtosecond resolution can be necessary, optical detectors
have a slower response by several orders of magnitude. One way of overcoming
this limitation is with Hong-Ou-Mandel interference. Another possible ultrafast
characterization method is to introduce a controlled delay between generated
signal and idler photons, overlap them spatially in a nonlinear crystal, and
detect the sum-frequency photon, in analogy to the autocorrelation of classical
laser pulses. We present experimental results where we demonstrate this latter
principle and discuss extensions of this work for the preparation of photonic
quantum states.
Terahertz nonlinear spectroscopy of free-carriers in direct bandgap
semiconductors
Paper 7763-11 of Conference 7763
Date: Sunday, 01 August 2010
Author(s): Luca Razzari, Francois Blanchard, Institut National de la Recherche
Scientifique (Canada); Fuhai Su, Univ. of Alberta (Canada); Gargi Sharma,
Institut National de la Recherche Scientifique (Canada); Ayesheshim K.
Ayesheshim, Tyler L. Cocker, Lyubov V. Titova, Univ. of Alberta (Canada); Heidi
C. Bandulet, Roberto Morandotti, Jean-Claude Kieffer, Tsuneyuki Ozaki, Institut
National de la Recherche Scientifique (Canada); Matthew E. Reid, Univ. of
Northern British Columbia (Canada); Frank A. Hegmann, Univ. of Alberta (Canada)
Ultrafast nonlinear processes have been extensively explored in the visible and
near infrared frequency range, thanks to the availability of ultrashort pulses
delivered by mode-locked lasers. Here, the combination of high intensities of
excitation together with a very fine temporal resolution have shed new light on
diverse aspects of condensed-matter dynamics [1]. On the other hand, this kind
of phenomena has remained relatively unexplored in the terahertz (THz) spectral
region (typically 0.1-10 THz), mainly because of the lack of sources delivering
high-energy, fewcycle THz pulses. Nowadays, this kind of sources is becoming
available [2,3], thus opening the route towards the understanding of new aspects
of radiation-matter interaction. Nonlinear interactions at THz frequencies
possess interesting properties and peculiarities: on one side, in this spectral
range one can observe an intermediate regime in which both electronic and ionic
motions contribute to the nonlinear dielectric function of a material. On the
other side, the very low energy per photon associated to this radiation allows
to neglect multiphoton interactions in semiconductors, thus opening up the
possibility of observing drift-velocity-based nonlinearities owing to free
carriers in this type of systems. While these processes were studied in the past
using relatively long THz pulses (time duration of several tens of nanoseconds)
[4,5], the above-mentioned new-generation of few-cycle THz sources allows now to
explore their ultrafast nature and dynamics in the picosecond domain [6]. In
particular, our investigation has been aimed at studying the ultrafast nonlinear
dynamics of free carriers in semiconductors and at developing the proper tools
for this new kind of THz spectroscopy. We have performed several nonlinear
experiments on free-carriers in direct bandgap semiconductors at THz
frequencies. Techniques as Z-scan [7], THz pump - THz probe [8], and optical
pump - THz probe [9] have been employed to explore nonlinear interactions in
both n-doped and photoexcited samples. The mechanism that dominates these
nonlinearities is found to be intervalley scattering and a simple mathematical
model adding this effect to a standard Drude-like response well explains our
experimental results. References [1] S. Mukamel, Principles of nonlinear
spectroscopy, Oxford University Press, (1999). [2] F. Blanchard et al., Opt.
Exp. 15 (20), 13212 (2007). [3] K.-L. Yeh, Appl. Phys. Lett. 90, 171121 (2007).
[4] A. Mayer and F. Keilmann, Phys. Rev. B 33, 6954 (1986). [5] A. Mayer and F.
Keilmann, Phys. Rev. B 33, 6962 (1986). [6] J. Hebling et al., IEEE J. Sel. Top.
Quant. Electron. 14, 345 (2008). [7] L. Razzari et al., Phys. Rev. B 79, 193204
(2009). [8] F. Blanchard et al., in preparation. [9] F.H. Su et al., Opt. Exp.
17 (12), 9620 (2009).
Nanocrystal lasing in the Auger-recombination-free regime using engineered
heterostructures
Paper 7756-23 of Conference 7756
Date: Wednesday, 04 August 2010
Author(s): Victor I. Klimov, Los Alamos National Lab. (United States)
Nanocrystal quantum dots show high photoluminescence quantum yields and
size-dependent emission colors tunable through the quantum-confinement effect.
Despite their favorable light-emitting properties, nanocrystals are difficult to
use in lasing because of fast optical-gain decay induced by nonradiative Auger
recombination. In this talk, I will discuss several approaches for resolving the
problem of ultrafast Auger recombination by using engineered carrier-carrier
interactions in various types of heterostructured nanocrystals.
Performance of a Schwarzschild imaging microscope for plasma diagnostics
Paper 7801-15 of Conference 7801
Date: Sunday, 01 August 2010
Author(s): Xin Wang, Baozhong Mu, Yi Huang, Zirong Zhai, Shengzhen Yi, Li Jiang,
Jingtao Zhu, Zhanshan Wang, Tongji Univ. (China)
Schwarzschild microscope system has been essential diagnostics in the intense
ultrafast laser-matter interaction research. A Schwarzschild type plasma
diagnostics system with numerical aperture of 0.1 and a magnification of 10 has
been designed, component fabricated, system assembled and experimental tested. A
Q-switched Nd:YAG laser at 1064 nm with a pulsed energy of 1 J was used to
ablate copper target to produce EUV emission above 10 nm. Mo/Si multilayers with
a thickness period of 9.5 nm and 30 layers pairs are deposited by magnetron
sputtering as a normal-incidence reflection coating at 18.2 nm and 5% bandwidth.
Since the spatial resolution of the microscope is limited by the CCD camera, LiF
is employed as the detector to achieve the sub-micron resolution for a field of
view of 2 mm using 600# copper mesh (bar width is 5μm) and 500lp/mm
transmittance grating as the object.
Spatio-temporal control of fields around nano-antennas
Paper 7757-16 of Conference 7757
Date: Sunday, 01 August 2010
Author(s): Daan Brinks, Marta Castro Lopez, Alberto G. Curto, Richard Hildner,
Tim H. Taminiau, Niek F. van Hulst, ICFO - Instituto de Ciencias Fotónicas
(Spain)
Nano-antennas concentrate electromagnetic fields in sub-diffraction limited
hotspots, whose position in time and space depends on the antenna-structure and
the incoming electromagnetic field. Antennas can therefore be combined with
ultrafast pulses to address femtosecond processes in nanometric volumes,
provided one takes into account and compensates for the dispersion of the
antenna-structures. We adapt the field of an excitation pulse to the dispersion
and resonances of an optical gap-antenna. This way we change and enhance the
localization of hotspots, while at the same time obtaining quantitative
information about the field dynamics around the structure. Our latest
experimental results will be presented.
Ultra-fast dynamics of spin and orbital magnetic moments of CoPd alloys probed
by time resolved x-ray magnetic circular dichroism
Paper 7760-21 of Conference 7760
Date: Tuesday, 03 August 2010
Author(s): Eric Beaurepaire, Christine Boeglin, Valérie Halté, Jean-Yves Bigot,
Victor Lopez-Flores, Jacek Arabski, Institut de Physique et Chimie des Matériaux
de Strasbourg (France); Christian Stamm, Nikolaus Pontius, Hermann Dürr,
Helmholtz-Zentrum Berlin für Materialien und Energie GmbH (Germany)
Ultrashort optical laser pulses (60 fs) have been used to change the
magnetization of a ferromagnetic CoPd alloy film, and probe its dynamics with
circularly polarized femtosecond X-ray pulses (100 fs), measuring the magnetic
dichroism at Co L2,3 edges. The use of sum rules allows disentangling for the
first time, the spin and orbital components of the magnetic moment. We show that
the dynamics of L and S are different. Our results show that the mechanism
responsible for the ultrafast laser induced demagnetization requires the concept
of spin-orbit interaction, and that the magneto-crystalline anisotropy energy is
an important quantity to consider.
Orientation determination for 3D single molecule diffraction imaging
Paper 7800-25 of Conference 7800
Date: Tuesday, 03 August 2010
Author(s): Chao Yang, Stefano Marchesini, Lawrence Berkeley National Lab.
(United States)
The latest development of ultrafast free electron laser makes it possible to
perform single molecule diffraction imaging. In such an experiment,
two-dimensional diffraction images of randomly oriented molecules of the same
type can be captured within femtosecond exposure time. To deduce the 3D
structure of the molecule at high resolution, we must solve two challenging
problems: 1) the determination of the relative orientations of 2D images; 2)
phase retrieval of a reconstructed 3D diffraction pattern. We will focus on the
first problem and discuss the use of common curve detection techniques to deduce
the relative orientation of 2D diffraction images.
Surface plasmon enhancement of third-generation conversion processes
Paper 7772-32 of Conference 7772
Date: Wednesday, 04 August 2010
Author(s): Jao van de Lagemaat, Allison C. Kanarr, Thomas H. Reilly III, Justin
C. Johnson, National Renewable Energy Lab. (United States)
In this presentation, I will describe a study of surface plasmon/exciton
hybridization with the aim of enhancing third-generation photoconversion
processes that have the theoretical capability of breaking the Shockley-Queisser
limit. Pentacene is a candidate for such a process called singlet fission, in
which a singlet exciton breaks up in two separate triplet excitons. We will show
results of ultrafast spectroscopy of pentacene on plasmonically active systems.
These measurements show altered excited state kinetics and show evidence of
enhanced formation of triplets indicating that hybridizing surface plasmons with
molecular states is a promising avenue of controlling energy conversion
pathways.
Detection of nucleic acids with graphene nanopores: ab initio characterization
of a novel sequencing device
Paper 7758-15 of Conference 7758
Date: Wednesday, 04 August 2010
Author(s): Tammie Nelson, Bo Zhang, Oleg V. Prezhdo, Univ. of Washington (United
States)
We report an ab initio study of the interaction of two nucleobases, cytosine and
adenine, with a novel graphene nanopore device for detecting the base sequence
of a single-stranded nucleic acid (ssDNA or RNA). The nucleobases were inserted
into a pore in a graphene nanoribbon, and the electrical current and conductance
spectra were calculated as functions of voltage applied across the nanoribbon.
The conductance spectra and charge densities were analyzed in the presence of
each nucleobase in the graphene nanopore. The results indicate that, due to
significant differences in the conductance spectra, the proposed device has
adequate sensitivity to discriminate between different nucleotides. Moreover, we
show that the nucleotide conductance spectra are not affected by its orientation
inside the graphene nanopore. The proposed technique may be extremely useful for
real applications in developing ultrafast, low cost DNA sequencing methods.
Course: Nanoplasmonics
Date: Thursday, 05 August 2010
Instructor(s): Mark I. Stockman, Georgia State Univ. (United States)
Nanooptics deals with optical phenomena and spectroscopy on the nanoscale, i.e.,
in the regions of space whose size is much smaller than the light wavelength.
While electromagnetic waves cannot be localized in the regions with sizes
significantly less than half wavelength, nanooptics is based on electric fields
oscillating at optical frequency. From the positions of the interaction with
matter and spectroscopy, such local optical fields mostly produce the same type
of responses as electromagnetic waves. Elementary excitations that are carriers
of energy and coherence in nanooptics are surface plasmons (SPs). These local
fields cause a wealth of gigantically enhanced optical phenomena of which the
surface enhanced Raman scattering (SERS) is the most studied and widely known.
This one-day course will encompass the fundamental properties and applications
of the surface plasmonics at the nanoscale. It will include coherent effects
associated with phase memory of the SPs, in particular, coherent control of
nanooptical phenomena. Nonlinear processes such as generation of harmonics and
two-photon excitation by nanoscale fields will also be covered. Ultrafast
(femtosecond and attosecond) phenomena are within the scope of this course. We
will also include quantum phenomena associated with properties of surface
plasmons as quantum quasiparticles such as quantum generation and fluctuations.
Along with fundamental properties of SPs, we will consider many applications of
nanoplasmonics, in particular, detection of ultrasmall amounts of chemical and
biological compounds, scanning near-field optical microscopes or SNOMs, and
nanolithography.
State-resolved exciton dynamics in quantum dots
Paper 7758-27 of Conference 7758
Date: Thursday, 05 August 2010
Author(s): Patanjali Kambhampati, McGill Univ. (Canada)
The semiconductor quantum dot is one of the canonical systems in nanoscience.
Whereas the nanometer size of these materials is obvious, the richer and more
meaningful issue is the presence of quantum confinement effects conferred by
virtue of size. One may qualitatively describe quantum dot electronic structure
like the textbook particle in a sphere. However, this simple picture misses the
vast majority of the processes which ultimately control the functionality of the
quantum dot. Our goal is to obtain a detailed picture of the rich inner workings
of the quantum dot. We introduce a mixed time/frequency domain ultrafast
spectroscopic approach which we denote State-Resolved Exciton Dynamics. We have
applied this approach to resolve several long standing issues central to quantum
dot science: 1) Hot exciton relaxation dynamics: radiationless transitions on
the nanoscale 2) Optical gain: recovering predictions from theory and revealing
new physics 3) Electronic structure of multiexcitons: creation of an artificial
periodic table 4) electron-phonon interactions: quantizing piezoelectricity The
power of this approach is reflected by our ability to predict aspects of
unrelated experiments, e.g. single dot blinking and multiple exciton generation.
In addition to the basic science of excitons in nanoscale materials, these
fundamental results have advanced the design principles for a broad range of
applications including: LEDs, lasers, solar cells, THz radiation sources,
piezoelectrics, and non-classical light.
Excitation dynamics in nanoscale materials for solar energy harvesting
Paper 7758-28 of Conference 7758
Date: Thursday, 05 August 2010
Author(s): Oleg V. Prezhdo, Univ. of Washington (United States)
Design of novel materials for energy harvesting and storage requires an
understanding of the dynamical response on the nanometer scale. A great deal of
experimental and theoretical work has been devoted to characterizing the
excitation, charge, spin, and vibrational dynamics in quantum dots, conducting
polymers, carbon nanotubes, inorganic semiconductors and molecular chromophores.
We have developed state-of-the-art non-adiabatic molecular dynamics techniques
and implemented them within time-dependent density functional theory in order to
model the ultrafast processes in these materials at the atomistic level and in
real time. Quantum dots (QD) are quasi-zero dimensional structures with a unique
combination of molecular and bulk properties. As a result, QDs exhibit new
physical phenomena such as the electron-phonon relaxation bottleneck and
efficient carrier multiplication, which have the potential to greatly increase
the efficiency of solar cells. Photoinduced charge separation across
molecular/bulk interfaces drives the dye-sensitized semiconductor solar cell. A
subject of active research, it creates many challenges due to the stark
differences between the quantum states of molecular and periodic systems, as
well as the different sets of theories and experimental tools used by physicists
and chemists. Our time-domain atomistic simulations create a detailed picture of
these materials. By comparing and contrasting their properties, we provide a
unifying description of quantum dynamics on the nanometer scale, resolve several
highly debated issues, and generate theoretical guidelines for development of
novel systems for energy harvesting and storage.
Widefield multiphoton excited fluorescence microscopy for animal study in vivo
Paper 7765-32 of Conference 7765
Date: Wednesday, 04 August 2010
Author(s): Shean-Jen Chen, Li-Chung Cheng, Chia-Yuan Chang, Hung-Wei Su,
National Cheng Kung Univ. (Taiwan)
A widefield multiphoton excited fluorescence microscope with a simultaneously
spatial and temporal focusing technique has been developed to provide fast
three-dimensional (3D) multiphoton fluorescence images fro animal study in vivo.
Unlike conventional multiphoton microscopy based on pixel by pixel scanning
technique, the wide-field multiphoton microscope only scans one dimension,
z-axis, to construct a 3D image. By using a Ti:sapphire femtosecond laser
oscillator as a seed laser for the femtosecond laser amplifier with a repetition
rate of 10 kHz, we raise the average power from 1.0 to 4.2 W, which is enough
power to excite the fluorescence in the area over 100 μm x 100 μm. The
fluorescence image signal is detected by an EM CCD, which frame rate might rise
up to 1 kHz according to the efficiency of fluorophore, so the widefield
multiphoton microscopy can provide very fast imaging fro animal study in vivo
such as monitoring brain neuron activity and liver metabolism.
Multiphoton excited whispering gallery mode ultraviolet lasing from ZnO
nano-multipods
Paper 7755-3 of Conference 7755
Date: Sunday, 01 August 2010
Author(s): Gaurav Shukla, Alika Khare, Indian Institute of Technology Guwahati
(India)
For c-axis oriented hexagonal ZnO nanodisks, microrods, and nano-multipods, the
lasing action can originate from whispering-gallery mode (WGM) cavity, in which
the light wave propagates circularly in the inner walls due to multiple total
internal reflections at the resonator's boundary. In this work, growth of ZnO
nano-multipods on ZnO seed layer using a two step hydrothermal process followed
by high temperature annealing is reported. Under excitation of a nanosecond
pulsed laser with 1064 nm wavelength, UV lasing emission from ZnO nano-multipods
was obtained. The UV lasing emission, resonant conditions, and laser mode
characteristics will be discussed using whispering-gallery mode mechanism.
3D microstructures of functional materials fabricated by multiphoton processing
Paper 7774-16 of Conference 7774
Date: Monday, 02 August 2010
Author(s): Xuan-Ming Duan, Xian-Zi Dong, Feng Jin, Wei-Qiang Chen, Zhen-Sheng
Zhao, Technical Institute of Physics and Chemistry (China)
Multi-photon process of nonlinear optical materials provides an excellent
opportunity for nanolithography with laser direct writing technique, which can
achieve not only nanometer scale resolution but also microstructure fabrication
in three-dimensions. In this paper, we will report the latest progresses on the
resolution of nanometer scale and 3D microstructures of functional materials
fabricated by multi-photon processing in our laboratory. The fabrication
resolution is downed to less than 50 nm. The fabricated 3D microstructures of
active materials, semiconductor-polymer nanocomposites exhibit excellent
properties such as ultra-low lasing threshold, tunable photonic bandgap and so
on.
Widefield multiphoton excited fluorescence microscopy with adaptive optics
Paper 7765-33 of Conference 7765
Date: Wednesday, 04 August 2010
Author(s): Shean-Jen Chen, Chia-Yuan Chang, Li-Chung Cheng, Hung-Wei Su,
National Cheng Kung Univ. (Taiwan)
This paper demonstrates the first integration for widefield multiphoton excited
fluorescence microscopy with adaptive optics to image mice in vivo. According to
distorted wavefront collected by defined image sharpness parameters, deformable
mirror is used to correct the distortion in real time. The adaptive optics
device corrects uniformity and system misalignment first and then reduces
biospecimen distortion to ensure perfect temporal focusing.
Entanglement-enhanced measurement of a completely unknown phase
Paper 7815-36 of Conference 7815
Date: Thursday, 05 August 2010
Author(s): B. L. Higgins, G. Y. Xiang, Griffith Univ. (Australia); D. W. Berry,
Univ. of Waterloo (Canada); H. M. Wiseman, G. J. Pryde, Griffith Univ.
(Australia)
Obtaining uncertainty in an estimate of an optical phase shift below the
standard quantum limit (SQL) requires employing nonclassical properties of
quantum mechanics, such as multiphoton entangled NOON states. Measurement of a
phase anywhere within 0 to 2π, however, additionally requires nontrivial quantum
control. Furthermore, the experimental construction of NOON states is
notoriously difficult. We present an adaptive phase measurement scheme using
entangled multiphoton states. We take a "bottom-up" approach by constructing an
experimental measurement protocol tailored to available states, employing
precharacterization of the apparatus and optimising feedback to achieve sub-SQL
measurement of a random phase.
Three-dimensional polymer microdevices with gold nanorods
Paper 7757-123 of Conference 7757
Date: Monday, 02 August 2010
Author(s): Shean-Jen Chen, Wen-Shuo Kuo, Chi-Hsiang Lien, National Cheng Kung
Univ. (Taiwan)
In this study, nonlinear multiphoton photocrosslinking and photopolymerization
of rose bengal and trimethylolpropane triacrylate monomers in solution have been
used to direct the three-dimension (3D) assembly of microdevices; moreover, we
also presents the first example of containing gold nanorods within the
photopolymerization. The experimental results show that the two-photon excited
photopolymerization containing the nanorods improves more efficiently of
decreasing the power density of femtosecond laser, and also provides a great
diversity of optical properties. The doped nanorods with two-photon luminescence
act as label molecules for internal microdiagnosis of 3D polymer microdevices.
The 3D structure with gradient spiral lattices exhibits a completely different
phenomenon on light propagation: these gradient 3D photonic structures may be
beneficial for developing polymer based optoelectronic devices and integrated
systems
Paper 7774-18 of Conference 7774
Date: Monday, 02 August 2010
Author(s): Zhen-Sheng Zhao, Xian-Zi Dong, Xuan-Ming Duan, Technical Institute of
Physics and Chemistry (China)
Multiphoton photopolymerization (MPP) is an emerging technique for the
fabrication of three-dimensional (3D) microstructures. Here, we report the
fabrication and properties of 3D photonic structures consisting of gradient
lattices. The properties of 3D structures were experimentally confirmed by
experimentals and FDTD calculations. The 3D structure with gradient quasidiamond
lattices could effectively expand the width of the PBG. The 3D structure with
gradient spiral lattices exhibits a completely different phenomenon on light
propagation. These gradient 3D photonic structures may be beneficial for
developing polymer based optoelectronic devices and integrated systems. The
details will be reported on the conference.
Terahertz nonlinear spectroscopy of free-carriers in direct bandgap
semiconductors
Paper 7763-11 of Conference 7763
Date: Sunday, 01 August 2010
Author(s): Luca Razzari, Francois Blanchard, Institut National de la Recherche
Scientifique (Canada); Fuhai Su, Univ. of Alberta (Canada); Gargi Sharma,
Institut National de la Recherche Scientifique (Canada); Ayesheshim K.
Ayesheshim, Tyler L. Cocker, Lyubov V. Titova, Univ. of Alberta (Canada); Heidi
C. Bandulet, Roberto Morandotti, Jean-Claude Kieffer, Tsuneyuki Ozaki, Institut
National de la Recherche Scientifique (Canada); Matthew E. Reid, Univ. of
Northern British Columbia (Canada); Frank A. Hegmann, Univ. of Alberta (Canada)
Ultrafast nonlinear processes have been extensively explored in the visible and
near infrared frequency range, thanks to the availability of ultrashort pulses
delivered by mode-locked lasers. Here, the combination of high intensities of
excitation together with a very fine temporal resolution have shed new light on
diverse aspects of condensed-matter dynamics [1]. On the other hand, this kind
of phenomena has remained relatively unexplored in the terahertz (THz) spectral
region (typically 0.1-10 THz), mainly because of the lack of sources delivering
high-energy, fewcycle THz pulses. Nowadays, this kind of sources is becoming
available [2,3], thus opening the route towards the understanding of new aspects
of radiation-matter interaction. Nonlinear interactions at THz frequencies
possess interesting properties and peculiarities: on one side, in this spectral
range one can observe an intermediate regime in which both electronic and ionic
motions contribute to the nonlinear dielectric function of a material. On the
other side, the very low energy per photon associated to this radiation allows
to neglect multiphoton interactions in semiconductors, thus opening up the
possibility of observing drift-velocity-based nonlinearities owing to free
carriers in this type of systems. While these processes were studied in the past
using relatively long THz pulses (time duration of several tens of nanoseconds)
[4,5], the above-mentioned new-generation of few-cycle THz sources allows now to
explore their ultrafast nature and dynamics in the picosecond domain [6]. In
particular, our investigation has been aimed at studying the ultrafast nonlinear
dynamics of free carriers in semiconductors and at developing the proper tools
for this new kind of THz spectroscopy. We have performed several nonlinear
experiments on free-carriers in direct bandgap semiconductors at THz
frequencies. Techniques as Z-scan [7], THz pump - THz probe [8], and optical
pump - THz probe [9] have been employed to explore nonlinear interactions in
both n-doped and photoexcited samples. The mechanism that dominates these
nonlinearities is found to be intervalley scattering and a simple mathematical
model adding this effect to a standard Drude-like response well explains our
experimental results. References [1] S. Mukamel, Principles of nonlinear
spectroscopy, Oxford University Press, (1999). [2] F. Blanchard et al., Opt.
Exp. 15 (20), 13212 (2007). [3] K.-L. Yeh, Appl. Phys. Lett. 90, 171121 (2007).
[4] A. Mayer and F. Keilmann, Phys. Rev. B 33, 6954 (1986). [5] A. Mayer and F.
Keilmann, Phys. Rev. B 33, 6962 (1986). [6] J. Hebling et al., IEEE J. Sel. Top.
Quant. Electron. 14, 345 (2008). [7] L. Razzari et al., Phys. Rev. B 79, 193204
(2009). [8] F. Blanchard et al., in preparation. [9] F.H. Su et al., Opt. Exp.
17 (12), 9620 (2009).