Results of investigations of input/output couplers basing on a 2D refractive index gradient are presented. A new simple method of its forming has been suggested and realized. This method allows to achieve a considerable narrowing of the directional beam diagram of such elements to the values no more than 25' - 30'. The whole (100%) light output was experimentally observed for all studied samples. The waveguide launching efficiency of about 20% was obtained using a He-Ne laser incident beam without any additional optimizing transformations on its width and divergence.

In the work a planar device based on single crystal Bi₁₂SiO₂₀ for controlling the light was studied. The direction of the light propagation in the layers of Bi₁₂SiO₂₀ and orientation of external electric field for high efficient mode conversion has been chosen. Characteristics of the device had been determined through mode analysis of this waveguide structure.

In the present paper, theoretical and experimental studies of formation and transportation of radiation of a high-power repetitive pulsed CO₂ laser in the optical system and along the 0.5 km horizontal atmospheric path have been performed. As is shown, the use of a light- guide, cooled metallic optics and adaptive system in the telescope provides efficient delivery of the high-power radiation.

The Asterix IV high power iodine laser is designed to deliver in a single beam output pulses with lengths ranges from 0.1 to 4 ns with a maximum power of 5 TW and an energy of up to 2 kJ. This laser has now achieved its projected output energy of 2.0 kJ and an output power of 4 TW. The Asterix laser has been developed on the basis of 10 years of experience with the 1 TW Asterix III laser and with the support of a 1D and a 3D pulse propagation code. Special emphasis has been put on obtaining an optimal overall efficiency of the laser system and a laser beam intensity profile as homogeneous as possible.

The method for phasing segmented mirrors by forming a reference (spherical or aspherical) surface by means of a system of small mirrors and an common-path interferometer has been developed. The method is being applied for the accurate comparison of curvature radii during shaping large mirrors surfaces (error approximately 10^-4 per cent).

The inertial confinement fusion program, the related high power glass laser development, and the progress in x-ray laser research in China are overviewed.

Results of experimental studies of bleaching of F^-₂ color centers (CC) in LiF crystals are presented. Bleaching of these centers was shown to take place in two-photon absorption from the excited state. The effect of bleaching on the emission of neodymium lasers with LiF:F^-₂-passive Q-switches was studied. Phenomenon of spontaneous narrowing of emission spectrum is due to arising in LiF:F^-₂ crystal of absorption grating (caused by destruction of F^-₂ CC), that has spectral-selective properties. Polarization characteristics of nonlinear transmission of YAG:Cr⁴⁺ crystal a model is developed, in which the absorption on the wavelength of 1.06 micrometers occurs due to three linear dipoles oriented along the crystallographic axes.

The paper summarizes the results of investigations and design of the imaging and forming systems with the compensation of the distortions, produced by the large-scale optical elements (primary mirror of the telescope etc.), with the help of the phase conjugation technique.

The technique of investigation is described as well as the experimental results on thermal stability of multi-layered Cr/C- and Mo/C-based X-ray mirrors to the X-ray radiation of a laser plasma source of 0.5 + 1.5 keV quanta energies, 1 + 25 ns pulse width and 0.01 + 0.2 J/cm² energy density. The X-ray pulsed heating of the mirror layers was approximately described by calculations and theoretically providing for the analysis of the experimental data.

Studying the optimum performance of molecular lasers requires information.on active medium parameters. Those in case of laser are translational and vibrational temperatures T, T1 , T2, T3' , and lasing molecule concentration., n. Vibrational temperatures have previously been determined in series investigations of electro discharge CO—laser active medium234S. But definition of concentration n potentially associated with large errors due to lack of lower laser level's vibrational temperature T1 measurements. Other temperatures have been estimated according to approximate model. As it was theoretically shown6 , to determine the inverse medium parameters without simplification, one should measure the small signal gains for lines of (0001_1000) and (0001_0200) traditional CO2 bands, (0002_1001) second sequence band and (O1'l-ll'O) hot band. Translational and vibrational temperatures and lasing molecule concentration were defined for CO—laser using the small signal gain measurements and theoretical scheme6.

A slab laser is operated thermal-stably with almost invariant divergence angle within the pump power ranging from 150 W to 10000 W. The maximum laser output power is over 150 W. The compressing of output divergence angle by placing suitable cylindrical lens into the resonator is also reported in this paper.

The form of the wave front of powerful iodine laser ISKRA-5 having an aperture of 700 mm has been investigated using a lateral shear interferometer. Results of determining the optical system aberrations and the monopulse WF form are presented.

To perform X-ray laser investigations on the laser facility ISKRA-4 a high-quality optical system with spherical surfaces has been developed focusing a laser beam into a line segment with high aspect ratio sides.

Hartmann method adaptation results are presented for wave-front form investigation on high power pulsed infrared lasers. Wave-front form investigation has been carried out on the Iodine Laser Facilities ISKRA-4 and ISKRA-5.

The phase conjugation of complex wave fronts is under investigation. The results of numerical simulations represented at this work covered mainly the PC of aberrated beams as well as the problem of diffraction lenses raster as a pat of radiation injection system. It is shown that some types of aberrations (coma-type for example) can not be compensated by PC at SBS.

Quasi-rectangular pulse of (tau) approximately equals 0.5 - 0.7 nsec duration has been shaped at `Iskra-5' output using the method of time splitting of initial light pulse followed by composition of its part with the necessary delay (strengthened in a tract). Numerical modeling of such pulse train in a forced tract shows pulse shape change in an area of wave overlapping due to a phase climb.

Experimental studies have been performed on the processes: chlorine utilization in the bubbler type singlet oxygen generator, the quenching of O₂(¹(Delta) ) in the OIL path, the propagation of the gas mixture O₂ + O₂ (¹(Delta) ) + H₂O throughout forward flow-type water vapor trap.

New possibilities of phase locking of a laser array are shown and analyzed for the case of optical coupling with the phase coordinated grating. It is suggested an unstable superresonator based on phase locking of a laser array in the conjugate resonator with the use of the phase coordinated grating. It is obtained an estimate of the supermode sensitivity of phase distortions. The possibility of forming an unstable resonator is demonstrated numerically.

The pulsed Nd-laser application to holographic relief manufacturing on the ion-beam sputtered chalcogenide layers is described. The masks formed by this way permit us to transfer the relief into glass and copper wafers.

A new scheme of the construction of laser driver for inertial confinement fusion researches is proposed. The scheme is based on the use of the second harmonic generation of the pulsed chemical oxygen-iodine laser as a pump source for solid-state lasers. A conceptual design of a 10 kJ class high-power laser set-up which allowed to get uniform irradiation of the target and precise profile of the laser pulse is considered.

The results of the theoretical and experimental study of four-wave mixing of repetitively pulsed CO₂ laser radiation is discussed. The PC-cell with the water-cooled mirror is used. Toluene and Xe-SF₆ gas mixture are used as nonlinear media.

The linear adaptive optical system with high-power CO₂ laser, operating in the phase conjugation scheme and providing the wavefront correction for the laser system has been experimentally studied. Results of test of a typical loop adaptive optics system based on the multi-channel Hartmann wavefront sensor and multi-actuator flexible mirror are reported. We also report development of devices for linear adaptive optics and means for controlling its units during operation. Prospects of using the neural networks for corrections of radiation wavefront distortions in the linear adaptive optical systems with high-power CO₂ lasers are analyzed.

Experiments realized, confirmed the possibility of distortions compensation, of forming telescope with composed mirror and diffractional optical element on it using phase conjugation for radiation wave length 1064 nm. Demonstrated the possibility of exit beam scanning.

The possibility of application of a neural network to data processing in an adaptive optical system is investigated. In case of a linear input/output transformation, the simple two-layer feedforward neuron structure is shown to be a good choice for heteroassociative reconstruction of the driving signals from the current data on the phase distribution. Several learning algorithms for the neural net are presented and the opportunity to construct the training set with the help of experiment is discussed.