Del Mar Photonics

SPIE Defence, Security+Sensing
25 - 29 April 2011
Orlando World Center Marriott Resort & Convention Center
Orlando, Florida, USA

Femtosecond lasers and applications - Del Mar Photonics femtosecond products

New generation of compact femtosecond system for laser-based detection and identification of biological materials

Paper 8032-3 of Conference 8032
Date: Monday, 25 April 2011

Author(s): Khan Lim, Yuan Liu, Matthieu Baudelet, CREOL, The College of Optics and Photonics, Univ. of Central Florida (United States); Evgueni Slobodtchikov, Peter Moulton, Q-Peak, Inc. (United States); Andrzej W. Miziolek, U.S. Army Research Lab. (United States); Martin C. Richardson, CREOL, The College of Optics and Photonics, Univ. of Central Florida (United States)

We show the use of a compact femtosecond lasers: a near-IR diode-pumped Yb:doped CPA system (PFL-1047, Q-Peak) delivering pulses at 1047 nm, with a duration of 600 fs and an energy of 1.8 mJ at a repetition rate of 250 Hz. Comparison with a nanosecond laser (Brillant, Quantel) in similar conditions on biological samples such as yeast. The spectral detection range from 140 to 920 nm shows different spectral features between the two regimes. The advantages of femtosecond and its implementation as a compact system for LIBS will be discussed as well as the future development for femtosecond LIBS on biological samples.

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Monolithic, narrow linewidth, polarization maintaining, thulium fiber laser using femtosecond laser written fiber bragg gratings

Paper 8039-15 of Conference 8039
Date: Monday, 25 April 2011

Author(s): Christina C. C. Willis, Joshua D. Bradford, CREOL, The College of Optics and Photonics, Univ. of Central Florida (United States)

We describe a monolithic diode-pumped thulium fiber laser incorporating femtosecond written fiber Bragg gratings (FBGs) for linewidth narrowing and wavelength stabilization. The laser cavity utilizes polarization maintaining, single-mode fibers. A Tm:fiber is spliced to passive fibers at either end, containing a high reflectivity (99%) FBG and a low reflectivity (34%) FBG output coupler respectively. This laser produces an average spectral width of 90 pm up to 5.24 W. The output is preferentially polarized parallel to the slow axis of the fiber with an average polarization extinction ratio of 17 dB from 0 to 5 W.

Generation and amplification of femtosecond laser pulses in Tm:fiber

Paper 8039-18 of Conference 8039
Date: Monday, 25 April 2011

Author(s): Robert A. Sims, Pankaj Kadwani, Lawrence Shah, Martin C. Richardson, CREOL, The College of Optics and Photonics, Univ. of Central Florida (United States)

We describe the generation and amplification of femtosecond pulses at 2-μm wavelength in Tm: fiber. The Tm:fiber mode-locked oscillator produces stable soliton pulses at 70 MHz repetition rate with 40 pJ pulse energy, centered at ~1.97 micron wavelength with ~8 nm (FWHM) spectral width. These pulses seed a Tm:fiber based Raman amplifier, which increases the energy up to 9 nJ. The spectrum is broadened up to 40 nm (FWHM) producing time bandwidth pulses <150 fs and the center wavelength can be shifted from ~1.97 - 2.15 micron. Chirped pulse amplification of the output from the Raman amplifier will be discussed.

Fiber-optic intrinsic Fabry-Perot interferometric sensors fabricated by femtosecond lasers
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Paper 8034-6 of Conference 8034
Date: Wednesday, 27 April 2011

Author(s): Tingyun Wang, Shanghai Univ. (China)

In this talk, intrinsic Fabry-Perot (F-P) micro-cavity interferometric sensors are reported. The fs lasers are directly focused into the SM fiber to fabricate an in-core mirror due to the laser induced relative RI difference. The F-P micro-cavity is realized by a pair of mirrors. Different writing methods and their relations with the sensor property are discussed. The insert loss of the sensor is ~0.2 dB. This enable it a good multiplexing capability. Meanwhile, high fringe visibility was achieved up to ~10 dB. Experiment results show that the reflection spectrum shifts linearly against the temperature with the sensitivity of 10.6 pm/℃.

Micro-structured sapphire fiber sensor for measurement of high-temperature in harsh environments
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Paper 8034-7 of Conference 8034
Date: Wednesday, 27 April 2011

Author(s): Xia Fang, Tao Wei, Yukun Han, Baokai Cheng, Xinwei Lan, Hai Xiao, Missouri Univ. of Science and Technology (United States)

A novel, assembly-free hybrid extrinsic/intrinsic Fabry-Perot interferometer (HEIFPI) has been fabricated by femtosecond laser micromachining on sapphire fiber. This kind of micro-structure can survive and maintain operational in high-temperature up to 1575 oC . The integrated micro-structure provides good long-term stability in extremely high temperatures, and the possibility to be deployed into the hot zones of advanced power and fuel systems as a temperature sensor.

Detection of microwave emission from solid targets ablated with an ultra-short pulsed laser

Paper 8037-22 of Conference 8037
Date: Thursday, 28 April 2011

Author(s): Joseph A. Miragliotta, Benjamin Brawley, Caroline Sailor, James B. Spicer, Jane W. Spicer, The Johns Hopkins Univ. (United States)

Over the past two decades, numerous reports have noted the generation of electromagnetic emission in the microwave region of the spectrum (~1 to 30 GHz) from targets that were ablated with high peak power, ultra-short pulsed laser (USPL) sources. Our group is investigating the generation of microwave emission from a variety of materials, including metals and insulators, via ablation with a femtosecond pulsed laser (peak powers in excess of 1012 Watts, pulse width ~ 30 fsec). Results include: microwave amplitude as a function of laser fluence, emission angle, and emission lifetime.

Terahertz light amplification by stimulated emission of radiation from optically pumped graphene

Paper 8023-3 of Conference 8023
Date: Monday, 25 April 2011

Author(s): Taiichi Otsuji, Stephane Albon Boubanga Tombet, Akira Satou, Tohoku Univ. (Japan); Victor Ryzhii, Univ. of Aizu (Japan)

[Invited] This paper reviews recent advances in terahertz light amplification by stimulated emission of radiation from optically pumped graphene. Possibility of terahertz negative dynamic conductivity is first described. Then experimental verification utilizing an exfoliated graphene under femtosecond IR laser pumping is demonstrated. The result will lead to a new type of terahertz lasers.

Spectroscopic terahertz imaging for food safety inspection

Paper 8023-24 of Conference 8023
Date: Tuesday, 26 April 2011

Author(s): Thomas Arnold, Martin De Biasio, Raimund Leitner, Carinthian Tech Research AG (Austria)

Recent developments in THz instrumentation in combination with a better understanding of the mechanisms behind the interaction of THz radiation and materials make THz spectroscopy and in particular THz spectroscopic imaging promising technologies for a wide range of applications. The present work describes a laboratory measurement system consisting of a state of the art femtosecond fiber laser based THz time domain imaging spectrometer. The system is used to investigate the possibilities to detect foreign bodies like wood, stone, glass, metal or plastic particles in dry food. Moreover, the chemical composition and moisture content are analyzed.

Atmospheric gas detection using broadband mid-IR thulium fiber-based sources

Paper 8039-19 of Conference 8039
Date: Monday, 25 April 2011

Author(s): Pankaj Kadwani, Robert A. Sims, CREOL, The College of Optics and Photonics, Univ. of Central Florida (United States); Jeffrey Chia, College of Optical Sciences, The Univ. of Arizona (United States); Faleh Altal, Masdar Institute of Science and Technology (United Arab Emirates); Lawrence Shah, Martin C. Richardson, CREOL, The College of Optics and Photonics, Univ. of Central Florida (United States)

We investigate the utility of a Tm:fiber laser, producing femtosecond pulses at 2-μm wavelength, for atmospheric trace gas detection. The system produces >500 mW average power with 9 nJ pulse energy and <150 fs pulse duration, with the center output wavelength tunable from ~1.97 - 2.15 μm. This smooth, ~40 nm wide (FWHM) spectrum enables simultaneous measurement of multiple CO2 absorption lines. We also report on this laser as a pump source for supercontinuum generation, with the goal of developing a compact and efficient broadband light source spanning the 3-5 μm wavelength range for trace hydrocarbon detection.

Laser terahertz emission microscope

Paper 8023-26 of Conference 8023
Date: Tuesday, 26 April 2011

Author(s): Masayoshi Tonouchi, Sunmi Kim, Shogo Fujiwara, Iwao Kawayama, Hironaru Murakami, Osaka Univ. (Japan)

[Invited] Recent progress of laser terahertz (THz) emission microscope (LTEM) is reviewed. Femtosecond lasers can excite the THz waves in various electronic materials due to ultrafast current modulation. The current modulation is realized by acceleration or deceleration of photo-excited carriers, and thus LTEM visualizes dynamic photo-response of substances. The developed systems have a minimum spatial resolution better than 0.6 μm, which is defined by the laser beam diameter. We also developed pump and probe type LTEM to visualize spatial dynamic carrier response and applied it to study photoconductive switches. In addition, we will discuss it application.

Detection and identification of explosives hidden under barrier materials: What are the THz-technology challenges?

Paper 8017-43 of Conference 8017
Date: Wednesday, 27 April 2011

Author(s): Arthur D. van Rheenen, Magnus W. Haakestad, Norwegian Defence Research Establishment (Norway)

We describe experiments where different explosives were hidden under common barrier materials, and THz radiation was used to detect and identify these explosives. Our THz system, a time-domain spectroscopy (TDS) system, is based on a femtosecond laser whose radiation is converted into THz radiation by a low-temperature grown GaAs photoconductive switch. A similar switch detects the reflected signal. The advantage of using a TDS system is that pulses reflected from the barrier and the actual explosive, arrive at different instances at the detector. However, partial temporal overlap occurs, hampering detection and recognition. In addition, there are other factors that make this process difficult. We shall address these issues and discuss strategies that may be used to face these challenges.


Characterization of photon-counting detector responsivity for nonlinear two-photon absorption process

Paper 8033-4 of Conference 8033
Date: Wednesday, 27 April 2011

Author(s): Suzana E. Sburlan, William H. Farr, Jet Propulsion Lab. (United States)

A non-linear two-photon absorption process has been characterized on a photon-counting detector. A focused 1550 nm beam triggers this process with 30 W of power on a Si detector. This system provides over 100 dB of isolation from signals at the bandgap wavelength of 1064 nm. For deep space optical communication systems, a single detector array can track an uplink beam as well as monitor the downlink signal for feedback control. A flight transceiver for communication between Earth and Mars is being designed based on this principle, which will detect two wavelengths using both single and 2-photon absorption processes.

Two-photon photoacoustic spectroscopy for noninvasive subsurface chemical diagnostics

Paper 8025-13 of Conference 8025
Date: Thursday, 28 April 2011

Author(s): Sudhir Dahal, Brian M. Cullum, John B. Kiser, Univ. of Maryland, Baltimore County (United States)

This talk will discuss proof-of-principle studies of two-photon excitation on model compounds. It was found that photoacoustic signals obtained from compounds like rhodamine 6G, rhodamine B and naphthalene, using two-photon excitation, suffered from less noise than when single-photon excitation was employed. Additionally, photoacoustic signals obtained from samples embedded in gelatin media, made to mimic tissues, have also shown a great deal of promise for moving towards real-time tissue diagnostics and margining.

Remote air lasing for trace detection

Paper 8024-16 of Conference 8024
Date: Monday, 25 April 2011

Author(s): Arthur Dogariu, James Michael, Richard B. Miles, Princeton Univ. (United States)

We report high gain infrared lasing in atmospheric pressure air from the focal region of an ultraviolet laser. The process involves resonant two-photon dissociation of molecular oxygen and simultaneous resonant two-photon pumping of an atomic oxygen fragment. We achieve exceptionally high gain lasing from the atomic oxygen, producing well collimated beams in both the forward and backward directions relative to the pumping UV laser. This is the first demonstration of a practical air laser. This provides a new approach to remote detection using nonlinear interactions such as stimulated Raman scattering with the backward propagating beam.

Experimental consideration of local realism with entangled photon pairs

Paper 8057-6 of Conference 8057
Date: Thursday, 28 April 2011

Author(s): Reinhard K. Erdmann, Michael L. Fanto, Paul M. Alsing, Corey Peters, Air Force Research Lab. (United States); Enrique J. Galvez, Colgate Univ. (United States); Warner A. Miller, Florida Atlantic Univ. (United States)

Bell's theorem and inequalities that stem from it addressed the conflict of quantum mechanics with certain understandings of local realism. We examine here the extent to which such 'hidden variables' can be represented by the ensemble of two-photon product states that exhibit local realism The experiments motivated by this exhibit high contrast between the perfect correlation of entangled quantum states compared with any two photon product states. Implications for quantum steering in terms of two-qubit Werner States are also assessed. The term was originally used by Schrodinger to depict the non-local influence on a (remote) quantum state enabled by quantum entanglement. This is distinct from any ability to relay information or, as has been demonstrated more recently, even to violate a Bell-type inequality.

Generalized active mode locking due to amplitude modulation in a ultra-short pulse laser using maple

Paper 8039-43 of Conference 8039
Date: Tuesday, 26 April 2011

Author(s): Daniel E. Sierra, Univ. EAFIT (Colombia)

The ultra-short pulse lasers have some important applications as: Ultrafast Excite-Probe for DNA, Ultrafast spectroscopy for control of chemical reactions, two photons microscopy for imaging technologies. To achieve this applications the deep comprehension of the physical phenomena such as mode locking both active and passive is needed. With this aim is necessary the elaboration of mathematical models for its analyses, which could be solved numerically or analytically. In the present work we want to study the generalized active mode locking due to amplitude modulation in ultra-short pulse laser when the laser parameters such as: the net-gain, the modulation strength and the normalized parameter are considered as functions of time. Our models will be solved analytically using computer algebra software (CAS), in specific Maple, in terms of special functions. In all cases the laser pulse properties will be determined by the properties of the corresponding special functions properties.

Novel local enhancement algorithm with 3D weighted median filters for image sequences

Paper 8063-38 of Conference 8063
Date: Tuesday, 26 April 2011

Author(s): Sos S. Agaian, Emanuel Silva, Josue R. Figueroa, The Univ. of Texas at San Antonio (United States)

In this study, we consider a novel 3D local image enhancement algorithm for image sequences extended from a 2D algorithm presented in previous work. The algorithm separates high frequency components of an image via a cascaded unsharp masking technique which are then enhanced using a modified adaptive contrast enhancement algorithm. The local image enhancement algorithm is modified by incorporating a 3D weighted mean filtering approach to the adaptive contrast enhancement algorithm. Experimental results from enhancing a sequence of two-photon excited fluorescence microscopy images in the MATLAB environment are then compared to the original images as well as other enhancement methods. An image processing scheme, which also includes a global image enhancement algorithm, for two-photon excited fluorescence microscopy images will be implemented and utilized as a comparison tool to evaluate the performance of the local image enhancement algorithm.