| Room Temperature Interband Cascade Lasers |
Jan 2010 |
7 pages |
| Authors:
M Kim; C L Canedy; C S Kim; W W Bewley; J R Lindle; J Abell; I Vurgaftman; J R Meyer; NAVAL RESEARCH LAB WASHINGTON DC OPTICAL SCIENCES DIV
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 | An analysis of the threshold current densities and differential slope efficiencies in interband cascade lasers with type-II active regions revealed lower Auger recombination rates than anticipated theoretically or using the data from prior experiments. Furthermore, a new design of the waveguide yielded room-temperature internal losses as low as approx. = 6/cm. The combination of these advances with improvements to the processing of narrow ridges has led operation up to 335 ... |
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| Fundamental Modeling and Design Strategies in Computational Photonics-Applications to Lasercom Through Clouds and Electro-Optical/Nanophotonics |
31 Dec 2009 |
16 pages |
| Authors:
Jerome V Moloney; ARIZONA UNIV BOARD OF REGENTS TUCSON
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| This summary highlights significant advances and discoveries under the support of the above grant. Two broad non-overlapping research topic areas were addressed in the project: I. Lasercom through clouds using novel partially spatially and temporally coherent laser beams, and II. Computational nanophotonics, plasmonics and metamaterials applied to new algorithm development with applications to atom/quantum dot traps, nonlinear harmonic generation in metamaterials and novel plasmonic high density data storage. The lasercom ... |
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| Free Electron Laser Stability Effects and Design of an Electrostatic Cathode Test Cell |
Dec 2009 |
104 pages |
| Authors:
Edmonson; Robert L III; NAVAL POSTGRADUATE SCHOOL MONTEREY CA
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| Developing the Free Electron Laser (FEL) as a weapon is of high interest to the United States Navy. This thesis aims to gain insight, through simulation of generic configurations of an oscillator and amplifier FEL, into the performance of an FEL and the effects of electron beam misalignments. It then compares simulation results to an existing experiment, and explores similarities and differences. Additionally, a new cathode test cell is designed. ... |
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| Improved Beam Jitter Control Methods for High Energy Laser Systems |
Dec 2009 |
88 pages |
| Authors:
Duane C Frist; NAVAL POSTGRADUATE SCHOOL MONTEREY CA
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| The objective of this research was to develop beam jitter control methods for a High Energy Laser (HEL) testbed. The first step was to characterize the new HEL testbed at NPS. This included determination of natural frequencies and component models which were used to create a Matlab/Simulink model of the testbed. Adaptive filters using Filtered-X Least Mean Squares (FX-LMS) and Filtered-X Recursive Least Square (FXRLS) were then implemented. Disturbance sources ... |
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| The Refractive Effects of Laser Propagation through the Ocean Surface and within the Ocean |
Dec 2009 |
72 pages |
| Authors:
Pavlos Xiradakis; NAVAL POSTGRADUATE SCHOOL MONTEREY CA
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| This thesis investigates the effect of the ocean water attenuation on a laser beam fired upward inside the ocean. The laser beam spreading due to scattering is approximated. The method used is a computer Monte Carlo simulation. Angular spreading of light caused by refraction at the sea surface is also studied and compared with the ocean results. The method is to simulate geometrical light rays passing through a randomly realized ... |
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| Simulation and Design Methods for Free-electron Laser Systems |
Dec 2009 |
64 pages |
| Authors:
Robert A Neuerman; NAVAL POSTGRADUATE SCHOOL MONTEREY CA
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| Modeling and simulation have proven invaluable to the design of various systems and planning of many experiments since the free-electron laser was invented in the 1970s. This thesis illustrates methods used for these tasks and for the validation and development of further theory. FEL systems and their components are described, briefly discussing how they fit into design considerations. Basic theory of FEL operation is reviewed, including the resonance condition, FEL ... |
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| Development of Ceramic Laser Element |
24 Nov 2009 |
13 pages |
| Authors:
Akio Ikesue; Yan L Aung; WORLD-LAB CO LTD NAGOYA (JAPAN)
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| Practical laser generation from polycrystalline ceramic materials has become available; furthermore, it is expected that ceramic laser technology will completely surpass the conventional glass and single crystal laser technologies in the future. In this work development of high quality ceramic laser materials was successfully done by control on macro-, micro- and nano-structural refinement. Transparency and optical homogeneity were confirmed to be high enough for the development of high power laser ... |
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| Spectroscopic and Kinetic Measurements of Alkali Atom-Rare Gas Excimers |
04 Nov 2009 |
25 pages |
| Authors:
S J Davis; W T Rawlins; K L Galbally-Kinney; W J Kessler; PHYSICAL SCIENCES INC ANDOVER MA
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| GOALS: Novel use of alkali/rare-gas molecules to efficiently couple high power diode arrays into alkali vapors -- Exciplex molecules absorb over much greater bandwidth * Control of inherent high optical gain to minimize ASE and optimize laser oscillation * Development of large volume resonators that allow efficient power extraction * Demonstration of high electrical-to-optical efficiency/power Exciplex assisted diode Pumped Alkali Laser (XPAL) * Education of a future generation of laser ... |
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| Liquid Crystal Based Optical Phased Array for Steering Lasers |
Oct-2009 |
192 pages |
| Authors:
Lei Shi; Philip Bos; KENT STATE UNIV OH
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| Beam steering technologies are attracting more and more research interests and attention because of the benefits of fast tuning, light weight, and synergy with adaptive optics. The liquid crystal OPA technology has been considered for small angle beam steering because of the small pitch, low driving voltages, large birefringence, flexibility, and electrical control. However, the large area resets of the phase profile caused by the fringe fields degrade the achievable ... |
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| Analysis of Carbon and Sulfur in Steel Samples Using Bench Top Laser-Induced Breakdown Spectroscopy (LIBS) |
Oct-2009 |
18 pages |
| Authors:
De; Lucia; Frank C Jr; Jennifer L Gottfried; Andrzej W Miziolek; ARMY RESEARCH LAB ABERDEEN PROVING GROUND MD WEAPONS AND MATERIALS RESEARCH DIRECTORATE
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| Laser-induced breakdown spectroscopy (LIBS) has been used for steel analysis for many applications. LIBS was used to confirm that the steel sample of interest is the correct steel type using linear correlation. Next, we attempted to identify trace carbon and sulfur in the steel sample using a standard LIBS laboratory setup. However, the most intense carbon and sulfur emission occurs in the vacuum ultraviolet region and, therefore, needs specialized spectrometer ... |
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| Laser Peening for Reliable Fatigue Life. Delivery Order 0025: Volume 1 - Simulation and Optimization of a Laser Peening Process |
Oct 2009 |
152 pages |
| Authors:
Gulshan Singh; Ramana V Grandhi; WRIGHT STATE UNIV DAYTON OH DEPT OF MECHANICAL AND MATERIALS ENGINEERING
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| We develop a finite element simulation of the 3D Laser Peening (LP) process and validate it with experimental results available from the literature. The simulation model is then used for parametric studies of the LP process including pressure pulse properties, spot properties, shot number, shot locations, shot sequencing, shot overlap configurations, and various geometries. The models were optimized via Mixed-variable Niche Particle Swarm Optimization (MNPSO), a tool developed for this ... |
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| Microplasma Channels and Large Arrays: Applications to Photomedicine, Microlasers, and Reactors on a Chip |
Oct 2009 |
20 pages |
| Authors:
J G Eden; ILLINOIS UNIV AT URBANA DEPT OF ELECTRICAL AND COMPUTER ENGINEERING
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| Under the support of AFOSR grant no. FA9550-07-1-0003, our laboratory at the University of Illinois has pursued the science and applications of microcavity plasmas, both as single devices and in the form of large arrays. Because of its unique properties, microplasma technology has (we believe) profound implications for photonics and electronics, with applications ranging from general lighting to biomedical diagnostics. During the past 3 years, the following milestones have been ... |
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| Power Enhancement of a Rubidium Vapor Laser With a Master Oscillator Power Amplifier (Postprint) |
15-Sep-2009 |
6 pages |
| Authors:
David A Hostutler; Wade L Klennert; AIR FORCE RESEARCH LAB KIRTLAND AFB NM DIRECTED ENERGY DIRECTORATE
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| A master oscillator power amplifier (MOPA) with variable amplifier gain lengths was built to demonstrate power enhancement of an alkali vapor laser. A small signal gain of 0.91 / cm for two different gain lengths was observed. For a 2 cm long amplifier gain length an amplification of 7.9 dB was observed. |
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| Z-scan Measurement of the Upconversion Coefficient in Er:YAG |
Sep-2009 |
20 pages |
| Authors:
Jeffrey O White; Robert Dibiano; Alexander B Fick; John E McElhenny; ARMY RESEARCH LAB ADELPHI MD SENSORS AND ELECTRON DEVICES DIRECTORATE
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| Solid-state laser research at the U.S. Army Research Laboratory (ARL) is currently emphasizing techniques for power scaling and achieving wavelengths in the eye-safer spectral region. We are studying erbium-doped yttrium aluminum garnet (Er:YAG), because it can be operated with a low quantum defect and has transitions around 1.6 micrometers. However, it suffers from cooperative pair upconversion, which can raise the lasing threshold, and thus lower the output power. In this ... |
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| Simulating Full-Waveform LIDAR |
Sep-2009 |
126 pages |
| Authors:
Angela M Kim; NAVAL POSTGRADUATE SCHOOL MONTEREY CA
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| LIDAR (LIght Detection And Ranging) is used to remotely measure the three-dimensional shapes and arrangements of objects with high efficiency and accuracy by making precise measurements of time-of-flight of pulses of light. Discrete return LIDAR systems provide a discrete series of elevation points corresponding to reflections from objects in the scene. Full-waveform LIDAR systems measure the intensity of light returned to the sensor continuously over a period of time. Relatively ... |
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| Intense and Broadband THz Source using Laser-Induced Gas Plasma |
26 Aug 2009 |
22 pages |
| Authors:
Norman Laman; Thomas Tongue; Jianming Dai; X Zhang; ZOMEGA TERAHERTZ TROY NY
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| The objective of the Phase I project was to create a compact, intense, broadband pulsed terahertz source suitable for use in a time domain spectroscopy system. This new source will cover a spectral range from 0.1 to 20 THz with an average power of 10 mW. In addition, we proposed to demonstrate spectroscopic measurements of explosives and related compounds. In this investigation, we performed some experiments with a gas cell ... |
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| Analysis of Capillary Guided Laser Plasma Accelerator Experiments at LBNL |
19 Aug 2009 |
8 pages |
| Authors:
Kei Nakamura; A J Gonsalves; D Panasenko; C Lin; Cs Toth; C G Geddes; C B Schroeder; E Esarey; W P Leemans; CALIFORNIA UNIV BERKELEY LAWRENCE BERKELEY LAB
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| Laser wakefield acceleration experiments were carried out by using a hydrogen-filled capillary discharge waveguide. For a 15 mm long, 200 micrometer diameter capillary, quasi-monoenergetic e-beams up to 300 MeV were observed. By de-tuning discharge delay from optimum guiding performance, self-trapping was found to be stabilized. For a 33 mm long, 300 micrometer capillary, a parameter regime with high energy electron beams, up to 1 GeV, was found. In this regime, ... |
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| Design and Prove-Out of a Material Tracking System With a Pad Printer and Laser Etcher System |
Aug-2009 |
61 pages |
| Authors:
Daniel Spicer; Tasha Roe; Jeff Hamby; Mark Powers; Lyle Sykes; ARMY ARMAMENT RESEARCH DEVELOPMENT AND ENGINEERING CENTER PICATINNY ARSENAL NJ MUNITIONS ENGINEERING TECHNOLOGY CENTER
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| A Material Tracking System and Bar-coding System was procured and installed at Kansas Army Ammunition Plant (KSAAP) as part of the Flexible Load, Assembly, and Pack (LAP) facility contract. The material tracking system uses a software program called Inventory Management, Process and Control Tracking System (IMPACTS) to provide paperless control of material on a production line. The bar-coding system consists of pad printers that apply 'blocks' of paint on the ... |
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| Measurement and Analysis of Upconversion Rates of Er:YAG at Room Temperature |
Aug-2009 |
14 pages |
| Authors:
M Dubinskii; G A Newburgh; T Sanamyan; ARMY RESEARCH LAB ADELPHI MD SENSORS AND ELECTRON DEVICES DIRECTORATE
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| We have measured upconversion fluorescence resulting from the excitation of room temperature 1% and 5% Er:YAG by a 1532 nm nanosecond pump source. Measurements of the fluorescence decay from the 4I13/2, 4I11/2, 4F9/2 and 4S3/2 manifolds to the 4I15/2 ground state manifold were observed over a wide range of excitation pulse fluence values. A unique set of upconversion parameters were extracted from the measurements using a modification of the traditional ... |
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| Vision Protection Army Technology Objective (ATO) Overview for GVSET VIP Day |
17-Jul-2009 |
8 pages |
| Authors:
Rob Goedert; ARMY RESEARCH DEVELOPMENT AND ENGINEERING COMMAND WARREN MI
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| These briefing charts discuss vision protection and protection for eyes and cameras from lasers. The problem is lasers can disable vision systems. The mission is to provide solutions protecting eyes and day-vision cameras from laser weapons. The objective is to develop materials that limit the amount of light energy allowed to the sensor, develop new optical system designs allowing the integration of advanced laser protection materials. |
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| Increased Ground Vibration Measurement Speed for Landmine Detection |
09 Jul 2009 |
95 pages |
| Authors:
James M Sabatier; MISSISSIPPI UNIV UNIVERSITY NATIONAL CENTER FOR PHYSICAL ACOUSTICS
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| The objective of this program, to demonstrate the feasibility of time-division multiplexing for rapid ground vibration measurements, has been achieved. Time-division multiplexing is a technique in which a multiple-beam laser Doppler vibrometer (MBLDV) passes over the ground while each beam measures a portion of the ground vibration. The signal from each beam is combined to determine the vibration pattern of that section of ground. In this way, the ground vibration ... |
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| Semiconductor Terahertz Technology |
15-Jun-2009 |
19 pages |
| Authors:
Gregory Sun; MASSACHUSETTS UNIV BOSTON
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| During this contract, we have investigated the THz laser source based on group-IV elements and their alloys that can be developed on Si substrates. The design work focused on the structure of the so-called quantum cascade laser (QCL). Specifically, we designed a Ge/Ge0.076Si0.19Sn0.05 QCL using intersubband transitions at L-valleys of the conduction band which has a clean offset of 150meV situated below other energy valleys (Gamma, Chi). The entire structure ... |
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| Aero-Optic Measurements Using a Laser-Induced Air Breakdown Beacon (PrePrint) |
04-Jun-2009 |
14 pages |
| Authors:
Matthew Whiteley; R Rennie; Garnett Cross; David Goorseky; David Cavalieri; Eric J Jumper; MZA ASSOCIATES CORP DAYTON OH
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| An experimental investigation into the optical behavior of a laser-induced air breakdown spark is described. The investigation concentrates on qualities of the air-breakdown spark, particularly the non-point-source character of the spark, that have a critical influence on the accuracy with which aero-optic aberration can be measured using the return light from the spark. Data are presented that show that the spark dimensions conform to established physical models, and baseline spark ... |
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| Laser Speckle and Atmospheric Scintillation Dependence on Laser Spectral Bandwidth: POSTPRINT |
01-Jun-2009 |
8 pages |
| Authors:
David Dayton; John St Gonglewski; Chad Arnauld; APPLIED TECHNOLOGY ASSOCIATES INC ALBUQUERQUE NM
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| Recent advances in low-cost high power diode lasers have made available a new type of illuminator source for LADAR remote sensing systems. These sources tend to be smaller more rugged, and have better power conversion efficiency than more conventional pumped crystal solid state lasers. They can be run in short pulse, or long pulse modes with pulse repetitions from DC to 10s of kilohertz. Although they don't have large optical ... |
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| Experimental Analysis of Perspective Elongation Effects Using a Laser Guide Star in an Adaptive-Optics System (POSTPRINT) |
01 Jun 2009 |
14 pages |
| Authors:
Kevin P Vitayaudom; Darryl J Sanchez; Denis W Oesch; Patrick R Kelly; Carolyn M Tewksbury-Christle; Julie C Smith; AIR FORCE RESEARCH LAB KIRTLAND AFB NM DIRECTED ENERGY DIRECTORATE
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| The use of a laser guidestar (LGS) for the purpose of a beacon in an adaptive-optics (AO) system is prone to perspective elongation effects on the spots of a Shack-Hartmann wavefront sensor. The elongated spots can vary in size over the subapertures and affect the gradient sensitivity of the sensor. The Air Force Research Laboratory (AFRL) has developed a LGS model that outputs gradient gains which represent the effects of ... |
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| Understanding the Plasma-Propellant Interaction through Experimental Modeling |
08-May-2009 |
38 pages |
| Authors:
Rik Blumenthal; AUBURN UNIV AL
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| The goal of the project was to develop an understanding of the plasma-propellant interaction, specifically the ignition of RDX by ETC. Based on experimental results a model of ETC ignition was developed in which ignition occurs through a process that resembles that of a primary explosive more than a secondary explosive. In this process, hydrogen ions in the ETC igniter plasma implant into the RDX surface are rapidly neutralized. The ... |
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| Electromagnetic (EM) Wave Attachment to Laser Plasma Filaments |
May-2009 |
50 pages |
| Authors:
D C Friedman; ARMY ARMAMENT RESEARCH DEVELOPMENT AND ENGINEERING CENTER PICATINNY ARSENAL NJ WEAPONS AND SOFTWARE ENGINEERING CENTER
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| This report explores the theoretical and experimental analysis of using plasma filaments generated by a femtosecond class laser system as a means for transmission of radio frequency (RF) electromagnetic (EM) waves. Theoretically, the plasma filaments are modeled as complex cylindrical wires in space for single and dual wire configurations. Attenuation as a function of distance is calculated for single wire transverse electric mode propagation and dual wire transverse electromagnetic (TEM) ... |
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| Dual Optical Ultra-Wide Band Laser Eyewear Transmission Field Evaluation Device Operation Manual |
May-2009 |
22 pages |
| Authors:
Tin M Aye; Jeffrey Wigle; PHYSICAL OPTICS CORP TORRANCE CA ELECTRO-OPTICS AND HOLOGRAPHY DIV
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| Dual Optical Ultrawide-Band Laser Eyewear Transmission (DOUBLET) Field Evaluation Device was developed by POC to meet the Air Force need for a simple device to measure the optical density (OD) of laser eye protection (LEP) spectacles, goggles, and visors with the OD 0 to 5, a precision of +/-0.1 OD at OD=1 and +/-0.5 at OD=5, across the VIS-NIR (400 nm to 1400 nm) spectral range. DOUBLET does not use ... |
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| High Efficiency, Room Temperature Mid-Infrared Semiconductor Laser Development for IR Countermeasures |
May-2009 |
21 pages |
| Authors:
Karen J Nordheden; Linda J Olafsen; KANSAS UNIV CENTER FOR RESEARCH INC LAWRENCE
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| This purpose of this grant focused on the optical and electronic characterization and fabrication of antimonide-based semiconductor lasers for infrared applications. Recent results with Optical Pumping Injection Cavity (OPIC) lasers includes 4 micrometer emission from a broadband laser and the measurement of spatial and temporal beam profiles. From August 2006 through December of 2007, the work was expanded to include the development of plasma etch processes in an Oxford Instruments ... |
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| Cooling and Trapping of Neutral Atoms |
30-Apr-2009 |
15 pages |
| Authors:
Harold Metcalf; STATE UNIV OF NEW YORK AT STONY BROOK RESEARCH FOUNDATION
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| We work on optical forces on atoms from non-monochromatic light. We have explored the Dichromatic force, measured its properties, provided a dressed state (Floquet) theory, and developed it into a practical tool for atomic nanofabrication. In addition. we have explored frequency swept light in adiabatic rapid passage to produce optical forces ten times larger than ordinary radiative forces. An extension of this theoretical description of the bichromatic force has led ... |
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| Frequency Stabilization of a Single Mode Terahertz Quantum Cascade Laser to the Kilohertz Level |
27-Apr-2009 |
9 pages |
| Authors:
Jerry Waldman; William D Goodhue; Thomas M Goyette; Andrew J Gatesman; Robert H Giles; William E Nixon; Andriy A Danylov; Michael J Coulombe; Xifeng Qian; MASSACHUSETTS UNIV LOWELL DEPT OF PHYSICS AND APPLIED PHYSICS
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| A simple analog locking circuit was shown to stabilize the beat signal between a 2.408 THz quantum cascade laser and a CH2DOH THz CO2 optically pumped molecular laser to 3-4 kHz (FWHM). This is approximately a tenth of the observed long-term (t sec) linewidth of the optically pumped laser showing that the feedback loop corrects for much of the mechanical and acoustic-induced frequency jitter of the gas laser. The achieved ... |
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| Doping Asymmetry Problem in ZnO: Current Status and Outlook. A Review of Experimental and Theoretical Efforts Focused on Achieving P-Type ZnO Suitable for Light-Emitting Optoelectronic Devices for the Blue/Ultraviolet Spectral Range |
24-Apr-2009 |
12 pages |
| Authors:
Hadis Morkoc; Vitaliy Avrutin; Donald Silversmith; VIRGINIA COMMONWEALTH UNIV RICHMOND
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| ZnO has gained considerable interest recently as a promising material for a variety of applications. To a large extent, the renewed interest in ZnO is fueled by its wide direct band gap (3.3 eV at room temperature) and large exciton binding energy (60 meV) making this material, when alloyed with e.g. Cd and Mg, especially attractive for light emitters in the blue/UV spectral region. Unfortunately, as with other wide-gap semiconductors, ... |
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| Wall-Plug Efficiencies of High-Power Free Electron Lasers Employing Energy Recovery Linacs |
23-Apr-2009 |
28 pages |
| Authors:
Phillip Sprangle; Joseph Penano; Bahman Hafizi; Ilan Ben-Zvi; NAVAL RESEARCH LAB WASHINGTON DC BEAM PHYSICS BRANCH
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| In a high average power free electron laser (FEL) the wall-plug efficiency is of critical importance in determining the size, complexity and cost of the overall system. The wall-plug efficiency for the FEL oscillator and amplifier (uniform and tapered wiggler) are strongly dependent on the energy recovery process. A theoretical model for electron beam dynamics in the energy recovery linac is derived and applied to the acceleration and de-acceleration of ... |
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| Study of Factors Determining the Gain Characteristics of DOIL Active Medium |
17-Apr-2009 |
56 pages |
| Authors:
Andrey A Ionin; Andrey Y Kozlov; Nina A Ionina; Nikolay P Vagin; Leonid V Seleznev; Dmitriy V Sinitsyn; Yuriy M Klimachev; Andrey A Kotkov; Igor V Kochetov; Nikolay N Yuryshev; Anatoliy P Napartovich; Oleg A Rulev; RUSSIAN ACADEMY OF SCIENCES MOSCOW LEBEDEV INST
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| The aim of the Project is to study experimentally and theoretically the possibility of working pressure increase and increase of singlet delta oxygen (SDO) yield in conditions of gas flow through the discharge region. Also, the properties of SDO and iodine containing gas mixture will be studied during the Project. In this connection, creation of experimental discharge facilities with gas flow is needed for efficient SDO production. During the work ... |
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| Rare-Earth Doped Gallium Nitride (GaN)- An Innovative Path Toward Area-scalable Solid-state High Energy Lasers Without Thermal Distortion |
Apr-2009 |
22 pages |
| Authors:
Michael Wraback; Mark Dubinskiy; ARMY RESEARCH LAB ADELPHI MD SENSORS AND ELECTRON DEVICES DIRECTORATE
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| We have demonstrated, for the first time, in situ neodymium (Nd) doping of gallium nitride GaN by plasma-assisted molecular beam epitaxy (PA-MBE). The Nd doping is controlled by the GaN growth conditions and the Nd effusion cell temperature. The Rutherford backscattering spectroscopy (RBS) and secondary ion mass spectrometry (SIMS) data indicated Nd doping as high as 8 at. %, with no evidence of phase segregation identified by x-ray diffraction (XRD) ... |
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| Real-Time Detection of Chemical Warfare Agents Using Multi-Wavelength Photoacoustics |
Apr-2009 |
18 pages |
| Authors:
Melvin Felton; Kristan Gurton; Richard Tober; ARMY RESEARCH LAB ADELPHI MD COMPUTATIONAL AND INFORMATION SCIENCES DIRECTORATE
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| We present a proof-of-concept study designed to investigate the utility of operating a conventional photoacoustic spectroscopy technique in a multi-wavelength mode applied to chemical vapor/aerosols for application of trace species detection and identification. The technique involves propagating three or more laser sources through a non-resonate, flow through photoacoustic cell. Each laser source is modulated at a different frequency, chosen at some convenient acoustic frequency. A portion of each laser's power ... |
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| Spectroscopy and Dynamics of Transient and Energetic Species |
Apr-2009 |
14 pages |
| Authors:
Daniel M Neumark; CALIFORNIA UNIV BERKELEY DEPT OF CHEMISTRY
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| Free radicals, weakly bound van der Waals complexes, and metal and semiconductor clusters are characterized by photodetachment of the corresponding negative ions using slow electron velocity-map imaging (SEVI), a recently developed, high-resolution (2-3 cm-1) variant of negative ion photoelectron spectroscopy. The SEVI spectrum of a negative ion yields the electron affinity of the neutral, term values for excited states accessible via one-photon detachment, and accurate vibrational frequencies for the ground ... |
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| High Average Power Diode Pumped Solid State Lasers: Power Scaling With High Spectral and Spatial Coherence |
30-Mar-2009 |
97 pages |
| Authors:
P S Kuo; J Wisdom; K Urbanek; S Sinha; A Serpry; T Plettner; Y Lee; R Gaume; H Bae; R Route; M Digonnet; Robert L Byer; S Wong; STANFORD UNIV CA
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| The main program objective was the development of a kilowatt class, cw Nd:YAG diode-laser-pumped solid-state laser (DPSSL) with quantum noise limited amplitude and phase, 24by7 operation capability and the ability to be repaired while in operation. The approach was a master-oscillator power-amplifier (MOPA) laser utilizing a series of zig-zag slab power amplifiers stages. We developed fiber amplifiers at the 200W level to generate power with high optical efficiency that can ... |
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| Q-Switched and Mode Locked Short Pulses from a Diode Pumped, YB-Doped Fiber Laser |
26-Mar-2009 |
115 pages |
| Authors:
Seth M Swift; AIR FORCE INST OF TECH WRIGHT-PATTERSON AFB OH GRADUATE SCHOOL OF ENGINEERING AND MANAGEMENT
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| A diode-pumped, ytterbium (Yb)-doped fiber laser system was designed and demonstrated to operate in continuous wave (cw), passively Q-switched and possibly passively mode locked operation. To our knowledge, this was the first fiber laser oscillator built at the Air Force Institute of Technology. A Cr4+:YAG (Chromium: Ytterbium Aluminum Garnett) crystal was used as a saturable absorber to generate Q-switched pulses. Attempts to mode lock the laser were performed using a ... |
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| A Theoretical Model Analysis of Absorption of a Three level Diode Pumped Alkali Laser |
Mar-2009 |
116 pages |
| Authors:
Lewis; Charlton D II; AIR FORCE INST OF TECH WRIGHT-PATTERSON AFB OH SCHOOL OF ENGINEERING AND MANAGEMENT
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| This paper models the absorption phenomena of light in a three level diode pumped alkali laser system. Specifically this model calculates for a user defined set of system parameters the attenuation of the input pump beam and characteristics of the bleached wave. Using Wolfram's Mathematical 6.0 software all necessary physics for an accurate description of absorption was modeled from first principles: energy levels, cross sections, spin-orbit kinetic processes, saturation frequencies, ... |
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| Assessment of Weather Sensitivites and Air Force Weather (AFW) Support to Tactical Lasers in the Lower Troposphere |
Mar-2009 |
83 pages |
| Authors:
Francesco J Echeverria; AIR FORCE INST OF TECH WRIGHT-PATTERSON AFB OH SCHOOL OF ENGINEERING AND MANAGEMENT/DEPT OF ENGINEERING PHYSICS
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| ATL scientists need to develop a full understanding of the interaction effects between a high-energy laser beam and the atmosphere through which it propagates. Achieving this understanding is important for many reasons. In particular, the high cost of DE weapons systems makes each propagation event expensive. Having an understanding of the atmosphere in which a high-energy laser propagates will increase efficiency and effectiveness of the ATL weapon system, which in ... |
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| Demonstration and Verification of a Broad Spectrum Anomalous Dispersion Effects Tool for Index of Refraction and Optical Turbulence Calculations |
Mar-2009 |
119 pages |
| Authors:
J J Cohen; AIR FORCE INST OF TECH WRIGHT-PATTERSON AFB OH GRADUATE SCHOOL OF ENGINEERING AND MANAGEMENT
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| An atmospheric optical turbulence strength model with a broad wavelength range of 355nm (ultraviolet) to 8.6m (radio frequencies) has been created at AFIT and implemented into the High Energy Laser End-to-End Operational Simulation tool (HELEEOS). This modeling and simulation tool is a first principles atmospheric propagation and characterization model. Within HELEEOS lies the High-Resolution Transmission Molecular Absorption (HITRAN) database, containing 1,734,469 spectral lines for 37 different molecules as of version ... |
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| Tunable Diode Laser Absorption Spectroscopy Verification Analysis for Use in the Combustion Optimization and Analysis Laser Laboratory |
Mar-2009 |
125 pages |
| Authors:
Christina R Serianne; AIR FORCE INST OF TECH WRIGHT-PATTERSON AFB OH GRADUATE SCHOOL OF ENGINEERING AND MANAGEMENT
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| The AFIT Combustion Optimization and Analysis Laser (COAL) laboratory has state-of-the-art laser diagnostic capability for combustion process. The research for this thesis served to enhance the COAL lab's capability. Currently, there are no known commercially available tunable diode lasers that produce Ultra-Violet radiation required for this analysis. Sum-frequency generation at 313.5 nm was utilized for high speed OH absorption and temperature measurements at a rate of 2kHz. The Tunable Diode ... |
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| Range Estimation Algorithm Comparison in 3-D Flash LADAR Data |
Mar-2009 |
102 pages |
| Authors:
Steven P Jordan; AIR FORCE INST OF TECH WRIGHT-PATTERSON AFB OH DEPT OF ELECTRICAL AND COMPUTER ENGINEERING
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| Peak, maximum likelihood (ML), and matched filter (MF) range estimation algorithms were tested in both simulated and measured 3-D Flash LADAR data. A normalized version of the MF was also developed and tested. Three different methods based on averaging were developed to calibrate the pulse width of the reference waveform used in the MF and ML algorithms. Simulation results show that a MF produces a bias when waveforms are cropped ... |
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| Multimode Regimes in Quantum Cascade Lasers: From Coherent Instabilities to Spatial Hole Burning |
10-Feb-2009 |
38 pages |
| Authors:
Federico Capasso; Franz Kaertner; HARVARD UNIV CAMBRIDGE MA SCHOOL OF ENGINEERING AND APPLIED SCIENCES
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| A systematic experimental and theoretical study of multimode regimes has been performed in high power mid-infrared quantum cascade lasers (QCLs). In narrow devices it is found that above a second threshold the laser spectrum dramatically broadens showing multimode operation with pronounced Rabi sidebands in the envelope of the spectrum. This represents the first direct evidence of the coherent instability associated with population oscillations at the Rabi frequency. For ridge widths ... |
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| Evaluation of a Portable Laser Depainting System |
05-Feb-2009 |
25 pages |
| Authors:
Marta A Jakab; SOUTHWEST RESEARCH INST SAN ANTONIO TX
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| SUMMARY: The laser was found to be efficient in removing CARC with coating removal rates comparable to those of sandblasting. Charring was observed in some cases during laser decoating, probably due to low laser fluence. Paint residue was found on the charred surface indicating incomplete paint removal. * Preliminary studies of selective coating removal showed that the laser can be optimized to remove the topcoat without damaging the primer layer. ... |
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| Non-Evaporative Cooling Using Spin-Exchange Collision in an Optical Trap |
03-Feb-2009 |
33 pages |
| Authors:
Jacob L Roberts; COLORADO STATE UNIV FORT COLLINS
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| This report describes, with references, three areas of research that addressed open questions relevant to the implementation of a novel nonevaporative cooling technique for ultracold gases, called collision-assisted Zeeman (CAZ) cooling. First, robust CAZ cooling requires efficient optical pumping in dense ultracold gases in which reabsorption of scattered photons is a serious limitation. Mitigation of reabsorption in such gases via the temporal and spatial modulation of light is reported. Second, ... |
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| Eliciting Action Potentials from Epidermal Stimulation of Skin Receptors Using Ultrashort Laser Pulses |
Feb-2009 |
16 pages |
| Authors:
Robert J Thomas; Douglas N Goddard; Michelle Imholte; Nicole Jindra; AIR FORCE RESEARCH LAB BROOKS CITY-BASE TX HUMAN PERFORMANCE WING (711TH)
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| Measurements of laser stimulated action potentials in the sciatic nerve of leopard frogs (Rana pipiens) were made using two ultrashort pulsed infrared lasers. The dorsal sides of the frog's hind limbs were exposed to 1540 nm and 1064 nm wavelengths at three separate spot sizes: 2 mm, 3 mm, and 4 mm. Energy density thresholds were determined for eliciting an action potential at each experimental condition. Results from these exposures ... |
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| Photonic Crystals for Infrared Nonlinear Optics |
Feb-2009 |
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| Authors:
Yoel Fink; Marin Soljacic; Peter T Rakich; Ayman Abouraddy; Zachary Ruff; Ofer Shopira; MASSACHUSETTS INST OF TECH CAMBRIDGE
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 | Here we summarize our progress in the development of 2- to 5-micron wavelength supercontinuum sources through grant number FA8650-05-C-5426 over the life of the program. The key developments over the past 3 years include 1) A proof-of-principle demonstration of a novel, efficient mid-IR Raman laser source in silica materials system, yielding efficient spectral transfer to 2.41 microns. (The demonstrated system can be naturally extended in wavelength to 5microns and beyond); ... |
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| Oxide Semiconductors with Non-Volatile Resistance Switching |
Feb-2009 |
23 pages |
| Authors:
M Skowronski; J A Bain; P A Salvador; CARNEGIE-MELLON UNIV PITTSBURGH PA
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| Metal-oxide-metal hetero-structures have been deposited by Pulsed Laser Deposition and sputtering and their I-V and switching characteristics investigated as a function of active oxide layer, top metal electrode type and structure, and oxide thickness. Non-volatile switching has been observed for structures containing (Pr,Ca)Mn03, (La,Ca)Mn03, (La,Sr)Mn03, Sr(Zr,Cr)03 and SrTi03 as the active layer and Mg, Cr, Cu, Ag, and Pt as the top metal. The electrical transport was due to space ... |
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Lasers and Masers
