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A fundamental formulation of plasmonic nanolasers from Fermi's Golden rule is developed by considering the inhomogeneity and dispersion of the cavity media. A Fabry-Perot nanolaser based on the plasmonic slab waveguide is used as an example and the studies have shown that the power confinement is inappropriate for plasmonic cavity modes.

A charge control model is developed for the transient analysis of the bipolar transistor laser in forward active mode in order to describe the dynamics of electron, photon and charge densities. The analysis of laser switching has shown that the turn-on time is reduced by increasing the base current or decreasing the spontaneous emission lifetime of electrons in the quantum well.

The possible causes of power limitation of nanosecond Nd:glass lasers are analyzed, where small-scale self-focusing is considered to be one of the main causes. A simple analytical dependence is found for an optimal distance between two nonlinear media and the maximum attainable energy in neodymium-phosphate glass lasers with rod amplifiers 10 cm in diameter is 400 J with pulse duration of 1 ns.

Broad-area vertical-cavity surface-emitting lasers (AVCSELs) grown in the antiwaveguiding approach are examined. Results suggest that the conventional AVCSEL device lases in high-order excited modes.

Future high-altitude laser systems may be affected by cirrus clouds. Laser transmission models were applied to measured and retrieved cirrus properties to determine cirrus impact on power incident on a target or receiver. A major goal was to see how well radiosondes and geostationary satellite imagery could specify the required properties. Based on the use of ground-based radar and lidar measurements as a reference, errors in cirrus-top and cirrus-base height estimates from radiosonde observations were 20%-25% of geostationary satellite retrieval errors. Radiosondes had a perfect cirrus detection rate as compared with 80% for satellite detection. Ice water path and effective particle size were obtained with a published radar-lidar retrieval algorithm and a documented satellite algorithm. Radar-lidar particle size and ice water path were 1.5 and 3 times the satellite retrievals, respectively. Radar-lidar-based laser extinction coefficients were 55% greater than satellite values. Measured radar-lidar cirrus thickness was consistently greater than satellite-retrieved thickness, but radar-lidar microphysical retrieval required detection by both sensors at each range gate, which limited the retrievals' vertical extent. Greater radar-lidar extinction and greater satellite-based cirrus thickness yielded comparable optical depths for the two independent retrievals. Laser extinction-transmission models applied to radiosonde-retrieved cirrus heights and satellite-retrieved microphysical properties revealed a significant power loss by all models as the laser beam transits the cirrus layer. This suggests that cirrus location is more important than microphysics in high-altitude laser test support. Geostationary satellite imagery may be insufficient in cirrus detection and retrieval accuracy. Humidity-sensitive radiosondes are a potential proxy for ground-based remote sensors in cirrus detection and altitude determination.

The optimization of microelectromechanical system (MEMS)-tunable vertical-cavity surface-emitting lasers (VCSELs) operating at wavelength around 1.55 m is discussed. Device tuning range, modal frequency splitting, threshold gains and modal selectivity are observed.

Comprehensive models of quantum-cascade (QC) operation were used for examining the thermal and Stark-effect rollover in QC lasers. Stark effect rollover was observed in devices with low thermal resistance and low injector doping levels before reaching the thermal rollover regime.

A new model is used for the calculation of the output characteristics of a fiber Bragg grating (FBG)-stabilized pump-laser module depending on the effective feedback from the grating. Findings reveal the capability of the proposed model in accurately simulating the properties of the wavelength-stabilized pump-laser module.

The nonlinear dynamics of a passive mode-locked fiber laser containing a long period fiber grating are evaluated. Results suggest the existence of passive mode-locking and autosoliton generation in the cavity of the laser.

A numerical model for multiwavelength actively mode-locked erbium-doped fiber lasers is proposed. Findings reveal that self-phase modulation (SPM) and cross-phase modulation (XPM) enhances gain competition suppression (GCS) and produces high-quality pulses in the large anomalous dispersion regime.

Optical phase conjugation (OPC) provides a means of dynamical correction of thermally induced aberrations in high-power laser systems. This method is particularly interesting for space applications because it is passive, mechanically simple, and allows for improved beam quality with only a small loss in power. To exploit it one has to assess the effect of the space environment, and in particular of space radiation, on the properties of the materials that are suitable for phase-conjugating mirrors (PCMs). We have investigated both materials providing OPC via stimulated Brillouin scattering and actual PCMs with regard to their radiation hardness. Proton- and gamma-irradiated PCMs in the form of 30-cm long silica rods and 5-cm long Te[O.sub.2] crystals were tested in a single frequency flash-lamp pumped Nd:YAG system delivering up to 220 mJ pulses with a 20 ns duration at a 50 Hz repetition rate. The difference in the reflectivity between irradiated and nonirradiated components was found to be within the measurement errors. Gamma irradiation of Te[O.sub.2] resulted in a decrease of the laser-induced damage threshold, while for silica possible changes were below the detection limit. Our results show that synthetic fused silica, and Lithosil in particular, can be used for generating the OPC in laser systems operating in a space radiation environment. OCIS codes: 190.5040, 190.5890, 160.6030, 140.3440, 350.5610.

Fiber delivery of 64.7 mJ laser pulses (~6 ns duration) from a Q-switched Nd:YAG laser operating at 532 nm is demonstrated. A custom diffractive optical element was used to shape the laser beam and facilitate coupling into a linear fiber array. This launch arrangement achieves an improvement in launch efficiency compared with a circular fiber bundle evaluated in previous work and the delivery of higher pulse energies is demonstrated. The bundle is capable of delivering light of sufficient pulse energy and, importantly, with suitable focusability, to generate a thin light sheet for the fluid flow measurement technique of particle image velocimetry (PIV). Fiber delivery offers an advantage, in terms of optical access, for the application of PIV to enclosed measurement volumes, such as the cylinder of a combustion engine. OCIS codes: 050.1970, 060.2310, 120.3940, 120.7250.

Byline: Mario Aigner-Torres (1,3), Jon Blundy (2), Peter Ulmer (1), Thomas Pettke (1,4) Keywords: Trace elements; Melting experiments; Plagioclase; LA-ICPMS Abstract: Plagioclase-melt partition coefficients (D) for 34 trace elements at natural concentration levels were determined experimentally in a natural MORB composition at atmospheric pressure using thin Pt-wire loops. Experiments were carried out at three temperatures (1,220, 1,200, and 1,180degC), and at three different oxygen fugacities (fO.sub.2 = IW, QFM, air) in order to assess the effect of fO.sub.2 on the partitioning of elements with multiple valence (Fe, Eu, Cr). Run products were analyzed by laser-ablation ICP-MS. Most trace element Ds increase slightly as temperature decreases, except for D .sub.Zr, D .sub.Fe, D .sub.Eu and D .sub.Cr that vary systematically with fO.sub.2. Applying the Lattice Strain Model to our data suggests the presence of Fe.sup.2+ entirely in the octahedral site at highly to moderate reducing conditions, while Fe.sup.3+ was assigned wholly to the tetrahedral site of the plagioclase structure. Furthermore, we provide a new quantitative framework for understanding the partitioning behaviour of Eu, which occurs as both 2+ and 3+ cations, depending on f[O.sub.2]and confirm the greater compatibility of Eu.sup.2+, which has an ionic radius similar to Sr, relative to Eu.sup.3+ in plagioclase and the higher Eu.sup.2+/ Eu.sup.3+ under reducing conditions. For petrogenetic basaltic processes, a combined fractionation of Eu.sup.2+--Sr and Fe--Mg by plagioclase has considerable potential as an oxybarometer for natural magmatic rocks. Author Affiliation: (1) Institute of Mineralogy and Petrography, Swiss Federal Institute of Technology, ETH Zentrum NO, 8092, Zurich, Switzerland (2) CETSEI, Department of Earth Sciences, University of Bristol, Wills Memorial Building, Bristol, BS8 1 RJ, UK (3) Department of Petroleum Engineering, University of Campinas (DEP-FEM-UNICAMP), 6122, Campinas, 13083-970, Brazil (4) Institute of Geological Sciences, University of Bern, Baltzerstrasse 1+3, 3012, Bern, Switzerland Article History: Registration Date: 05/12/2006 Received Date: 19/04/2006 Accepted Date: 27/11/2006 Online Date: 17/01/2007 Article note: Communicated by T. L. Grove.

The National Ignition Facility (NIF) is the world's largest laser system. It contains a 192 beam neodymium glass laser that is designed to deliver 1.8 MJ at 500 TW at 351 nm in order to achieve energy gain (ignition) in a deuterium--tritium nuclear fusion target. To meet this goal, laser design criteria include the ability to generate pulses of up to 1.8 MJ total energy, with peak power of 500 TW and temporal pulse shapes spanning 2 orders of magnitude at the third harmonic (351 nm or 3[omega]) of the laser wavelength. The focal-spot fluence distribution of these pulses is carefully controlled, through a combination of special optics in the l[omega] (1053 nm) portion of the laser (continuous phase plates), smoothing by spectral dispersion, and the overlapping of multiple beams with orthogonal polarization (polarization smoothing). We report performance qualification tests of the first eight beams of the NIF laser. Measurements are reported at both 1[omega] and 3[omega], both with and without focal-spot conditioning. When scaled to full 192 beam operation, these results demonstrate, to the best of our knowledge for the first time, that the NIF will meet its laser performance design criteria, and that the NIF can simultaneously meet the temporal pulse shaping, focal-spot conditioning, and peak power requirements for two candidate indirect drive ignition designs. OCIS codes: 140.0140, 140.3610, 140.3070.

A Shack-Hartmann sensor nonintrusive measurement for the temperature profile in a heat-capacity neodymium-doped glass rod is proposed. This technique is possible because the optical path length of the rod changes with temperature linearly over a wide range. The temperature change of the solid-state laser rod is often recorded by using a thermocouple, thermal camera, or phase-shifting interferometer. Based on an analysis of temperature-induced changes in length and index of refraction, we can get the temperature profiles from the wavefront reconstructions in real time. The results suggest the Shack-Hartmann sensors could replace microbolometer-based thermal cameras and phase-shifting interferometers for dynamic temperature profiles in heat-capacity laser rods with particular advantages. A strange temperature chaos of the Nd:glass rod just after the pump cycle is discovered. OCIS codes: 120.0120, 120.6780.

A system combining pressurized capillary gel filtration with online laser fight scattering and microscopic imaging, particularly suitable for biological applications, has been developed. Structural information of eluted materials in the gel filtration provides important clues about their behavior and how they interact with light. It also reveals that the dispersion of the column packing materials is the major limiting factor in the improvement of detectability. Surprisingly, it is found that eluted lysozymes actually scatter light coherently with two distinctive features: a very strong scattering characteristic of constructive interference and a very weak scattering consistent with destructive interference. A variation of the incident angle by 2[degrees] of the laser beam caused a swing between the two features. Albumins and large blue dextran particles scatter light simply as individual particles.

Transformation circle theory is simpler than other methods for analyzing laser resonators. In our analysis only a circles and simple mathematical knowledge are used to analyze the stability and calculate the parameters of the laser resonator, which further simplifies the transformation theory. The results agree well with the well-known matrix theory. Two- and three-mirror (including a thermal lens) laser resonators are used as examples to present the stability formula and the Gaussian beam dimensions at the mirrors. Furthermore, we apply the commonly used example in which the laser medium is close to the cavity mirror. OCIS codes: 080.2720, 140.3410, 140.4780.

Abstract Photoepilation, utilizing lasers and noncoherent light sources, is designed to irradiate as much of the follicular unit as possible, with melanin as the target chromophore. Wavelength absorption should generate [...]

Abstract Background: Laser hair removal targets melanin in the hair shaft. The abundance of melanin in the epidermis of patients with dark skin color has always been regarded as hazardous [...]

A numerical simulation method for a supersonic chemical oxygen-iodine laser is developed. The model is a combination of a three-dimensional computational fluid dynamics code without kinetics and a detailed one-dimensional, multiple-leaky-stream-tubes kinetics code. In the proposed method, the detailed flowfield characteristic is calculated by solving a full Navier-Stokes equation that does not involve chemical reactions, and the resultant temperature, velocity, and mixing characteristics are input to the kinetics code as its boundary conditions. A 'nonuniform coefficient' is introduced to transform the fluid-dynamic mixing to the diffusive mixing term of the kinetics code. As a result, precise predictions of the gain distribution and laser output are given with a reasonable computational cost. The developed model is applied to the X-wing-type supersonic mixing chemical oxygen-iodine laser, which we have developed, and the calculated gain and output power are compared with the experimental results. The excellent agreements of calculated and experimental results show the validity of the developed method.

A method for analyzing organoselenium and organic acid metabolites using laser desorption from graphite surfaces coupled to vacuum ultraviolet single photon ionization mass spectrometry (LD/SPI MS) is described. The 1-10-fmol sensitivity and linear dynamic range allows quantitative detection of selenomethionine, trimethylselenonium ion, methylselenogalactosamine, and 1[beta]-methylseleno-N-acetyl-D-galactosamine in complex biological samples such as human urine. In addition, common urinary metabolites such as tartronic, glutaric, orotic, uric, suberic, and hydroxyhippuric acids, are readily detected. Screening and quantitative detection of these organoselenium and organic acid metabolites is achieved within minutes. The results are also consistent with those obtained using high-performance liquid chromatography tandem mass spectrometry techniques. The study demonstrates the viability of matrix-free LD/SPI MS for molecular characterization and quantitive analysis of biological metabolites in the m/z 10-500 range that are present in complex biological fluids.

A new model for analyzing the laser-induced damage process is provided. In many damage pits, the melted residue can been found. This is evidence of the phase change of materials. Therefore the phase change of materials is incorporated into the mechanical damage mechanism of films. Three sequential stages are discussed: no phase change, liquid phase change, and gas phase change. To study the damage mechanism and process, two kinds of stress have been considered: thermal stress and deformation stress. The former is caused by the temperature gradient and the latter is caused by high-pressure drive deformation. The theory described can determine the size of the damage pit. OCIN codes: 310.3840, 140.3330, 140.3440.

We evaluate vertical-cavity surface-emitting lasers (VCSELs) reliability for next-generation high-productivity computers wherein several hundreds of terabits of bandwidth are envisioned. VCSEL failure rates are modeled, and an empirical relationship for VCSEL scaling versus bit rate and aperture is presented to explore the reliability of VCSEL-based links. The effects of VSCEL sparing, water cooling, and redundancy at the system level are analyzed. OCIS codes: 200.4650, 250.7260, 060.2360.

The inclusion of field ionization models in kinetic plasma simulations is desired in several applications. The ionization rates in these models are sensitive to noise in the electric field; however, and in some cases, spurious 'numerical' ionization may dominate the physical ionization. In this paper, analytic ionization rates are obtained as a function of the noise spectrum of the electric field. These expressions have applicability to several settings, including colored noise, as are obtained from digital filters. As such, they provide a means for quantitatively assessing the efficacy of candidate noise mitigation schemes, such as increasing the computational particle number, temporally averaging the electric field, or applying more sophisticated digital filtering techniques. Index Terms--Ionization, level-crossing statistics, particle-in-cell simulation, short-pulse lasers.

A high efficiency Yb:YAG/YAG composite slab laser is presented, in which the corner-pumped scheme is adopted. The slab is a composite crystal of Yb:YAG bonded thermally with undoped YAG at both edges. The pump light from diode arrays is coupled into the slab through four chamfers at the four corners independently. The pump absorption efficiency is studied, and an analysis method has been developed as a guide to optimize the geometric parameters of the composite slab, to obtain higher pump absorption efficiency and uniformity. The influence of the internal thermal lens on the laser resonator is analyzed. A 1016 W continuous-wave output has been obtained with the slope efficiency and optical-to-optical efficiency of 42.8% and 34.4%, respectively. OCIS codes: 140.3460, 140.3480.

Vanadium dioxide (V[O.sub.2]) and vanadium pentoxide ([V.sub.2] [O.sub.5]) thin films are irradiated by a near-infrared continuous-wave laser beam and the dynamic optical limiting performance is measured. The temperature varying with time of the films induced by a laser beam is also recorded by an IR thermal sensor. Under the irradiation of a laser beam with an intensity of 255 W/c[m.sup.2] and a spot diameter of 2 mm, the laser beam transmittance of the V[O.sub.2]2 film decreases from 47% before phase transition to 28% after phase transition, and the response time is ~200 ms; the laser beam transmittance of the [V.sub.2][O.sub.5] film decreases from 51% before phase transition to 24% after phase transition, and the response time is ~40 ms. The optical limiting is realized by this laser heating-induced phase transition. OCIS codes: 140.3360, 310.6860, 120.6780, 140.6810.