Pavel P. Geiko

Optical Properties of AgGaxIn1-xSe2 Crystals

Optical properties: absorption coefficients and refractive indices in the near and middle IR range of nonlinear AgGatildeoIn1-tildeoSe2 crystals have been studied. Sellmeier coefficients for the crystals at different In content are presented. An experiment on TEA- and Q-switched CO2 laser SHG was carried out and 10.9% SHG efficiency has been achieved.

Development and testing of the lidar gas analyzing complex

Differential Absorption Lidar Complex is designed for field scientific investigations, as well as for teaching Lidar designers and future operators. The Complex consists of two independently working Lidar Systems and the equipment for in situ measurements. Field test results are presented.

Detection of trace concentration of some simple pollutants in Tomsk

The differential absorption method is the best one from the point of view of its potentialities in applications to solving the problems of sensing atmospheric gaseous pollutants. The middle IR spectral range from 2 to 14 micrometers is most attractive for measurements since well-resolved absorption spectra of almost all the atmospheric gases are observed here. This paper presents some results of monitoring several trace atmospheric constituents, including CO, C2H4 and NH3 using a gas analyzer, based on the use of two CO2 lasers and a set of frequency converters. The gas analyzer with a discretely frequency-tuned CO2 laser was taken as the basic device for this study. Use of a ZnGeP2 monocrystal for frequency doubling enables one to measure CO concentration in addition to concentrations of ethylene, water vapor, ammonia under field conditions.

Second harmonic generation of TEA CO2 lasers with high output power for lidar systems

The goal of this work is possibility investigation for developing of high efficient and high output power mini TEA CO2 laser Second Harmonic Generators (SHG) applicable to use in mobile gas analysis lidars. Efficiency of SHG with Te, CdGeAs2, ZnGeP2, AgGaSe2 AgIn0.4Ga0.6Se2, Tl3AsSe3, and GaSe nonlinear crystals was estimated by solving shortened equations for interacting waves in combination with thermodynamic one. The latter equation allowed us to take into account the crystal self-heating effect (thermal refraction and lens effect) and inhomogeneous disturbance of SHG phase-matching, as well as took into account an energy transfer from the pumping wave to SH, optical losses, aperture and diffraction effects. In so doing we demonstrate SHG efficiencies using the following CO2 pumping laser parameters: wavelength (lambda) equals 9.3 micrometer, pulse duration (tau) equals 50 ns, pulse repetition rate f equals 1000 Hz, pulse power E equals 50 mJ. The pulse repetition rate satisfies condition of the frozen atmosphere and the energy is sufficiently large for working on topographic targets that are 10 km off using both CO2 laser emission and its SH (the conversion efficiency is from 5 to tens of percent). Besides, we believed that the laser is operated in TEM00 mode, the pumping intensity was assumed to be a half of the threshold pumping intensity (it provides for stable SHO operation), the time shape and intensity distribution in the beam cross section were assumed to be Gaussian. These parameters as a whole correspond to ones of the typical mini TEA CO2 lasers, which are used in mobile lidars. Additional angular tuning of the crystals, that maximizes SHG efficiency, as well as the optimal crystal lengths, giving its absolute maximum for the fixed pumping pulse repetition rate, were also determined.

ZnGeP2 crystal is the leader among nonlinear crystals for middle IR

The results of 25-year work on design of middle IR ZnGeP2 crystal growing technology are summed up, so as of the 20-year work on investigation of the parametric frequency converters with this crystal.

New optical material for tunable coherent infrared source for different applications

Growth and nonlinear optical properties of HgGa2S4 and mixed chalcopyrite Cd4Hg06Ga2S4 & AgGaGeS4 crystals have beenreported. Sellmeier coefficients have also been developed from the measured refractive indices in all these crystals. Nonlinearlaser device application has also been explored.Keywords: Nonlinear material, tunable laser device, Sellmeier coefficients, chalcopyrite crystal

Laser frequency converters for aerosol and gas lidar systems

Estimations are carried out on creation possibilities of all solid state laser sources capable significantly or fully to solve the problem of the universal Aerosol-Gas Lidar System design. Best existing Ho2+:ILF and Nd:YAG lasers supplied with LBO, KTA, KTP, BBO, CLBO, DLAP; GaSe, GaSe:In, AgGaxIn1-xSe2, LiInS2, LiInSe2, AgGaS2, AgGaxIn1-xS2, and HgGa2S4 frequency converters are considered. The investigation results show development of UV to FIR laser source is really to carry out with efficiencies from one-two up to several tens pro cents in several ways.

High‐efficiency frequency conversion of IR lasers with ZnGeP2 and CdGeAs2

The problem on developing effective, reliable parametric frequency converters (FC) for overlapping the middle IR by the converted spectrum of the available lasers has not been solved as yet. This is caused by low nonlinear susceptibility of nonlinear crystals widely used and by relatively low optical quality, damage levels and small length of the new promising crystals.

Laser frequency converters for Universal Lidar system

We present phase-matching conditions and widths, results on estimations of frequency conversion efficiencies, and other potential characteristics of frequency converters.

Possibilities and experimental investigation of parametric frequency converters with LiInSe/sub 2/, AgGaGeS/sub 4/, HgGa/sub 2/S/sub 4/ and Hg/sub 0.65/Cd/sub 0.35/Ga/sub 2/S/sub 4/ crystals

Second harmonic generation of 9 /spl mu/m emission band of CO/sub 2/ laser is for the first time realized with a number of new nonlinear crystals: biaxial LiInSe/sub 2/, AgGaGeS/sub 4/ (that is solid solution AgGaS/sub 2/:GeS/sub 2/ or Ag/sub x/Ga/sub x/Ge/sub (1-x)/S/sub 2/, or AgGaGe/sub x/S/sub 2(1+x)/ at x=0.5) and uniaxial HgGa/sub 2/S/sub 4/, Cd/sub 0.35/Hg/sub 0.65/Ga/sub 2/S/sub 4/ (solid solution HgGa/sub 2/S/sub 4/:CdGa/sub 2/S/sub 4/ with mixing ratio x=0.35). For LiInSe/sub 2/ and AgGaGeS/sub 4/ it is first type of frequency conversion realized at some time or other. The main feature of these crystals is a wide range transparency from 0.4-0.6 to 12.5-16.2 /spl mu/m. Their damage thresholds for 30 ns TEA CO/sub 2/ laser pulses at 9.55 /spl mu/m is determined as 1.7 to 2.3 times higher than for popular middle IR crystals such as ZnGeP/sub 2/ or AgGaSe/sub 2/. Parameters of second harmonic generation were determined correctly in comparison with ZnGeP/sub 2/ crystals at 33 ns pump pulses and intensities that are about 28.5% (40 MW/cm/sup 2/) of damage thresholds of ZnGeP/sub 2/. As high as 7% external peak power efficiencies (4.7% in energy) is typical for orange and yellow phases of 3.1 mm HgGa/sub 2/S/sub 4/ crystal such pumping that is only 13% of its damage threshold. Efficiencies as high as 0.45% and 0.3% are realized in 2.1 mm AgGaGeS/sub 4/ crystal at pump intensities-that is only 11% of the damage threshold. Phase-matching angles, spectral dependence of second harmonic generation efficiencies, and angular and spectral phase-matching widths are investigated in detail.