Our new completely nonlinear hydrodynamic numerical code permits to study the temporal evolution of wake fields and a laser pulse in conditions quite near to the wavebreaking or cavitation. It is shown that a short narrow laser pulse of the relativistic intensity generates so strong plasma wave that the electron trajectories intersection can appear. In the case of longer laser pluses, those are undergone the self-modulation effect, the cavitation arises behind a laser pulse in the region of the wavefield even for the nonrelativistic pulse intensities.

A complex self-sustained 1D hydrodynamics model of interactions model of interactions of ultrashort laser pulses with solid targets has been developed. The main application of the model is the interpretation of experiments through the comparison of the code result with output of various types of diagnostics. It can be also used in search of optimum experimental conditions for certain proposed applications of such systems.

The first terawatt picosecond CO₂ laser, PITER I, is under commissioning at the Brookhaven Accelerator Test Facility. PITER I consists of a single-mode TEA oscillator, semiconductor optical switch, and two stages of the multi- atmosphere amplifiers. We report on design, simulation, and tests of the 10 ATM final amplifier that allows multi- terawatt peak power extraction in a picosecond laser pulse.

The ionization dynamics of plasma, created on the surface of solid-state target irradiated by high power sub-picosecond laser pulses, is studied. the laser energy absorption, heating, expansion and ionization of the target matter are taken into account self-consistently. We have employed and compared two different models of ionization: quasistationary model and non-stationary model of average ion. Next, we have demonstrated the influence of ionization processes on plasma dynamics.

It is shown, that the essential laser pulse energy depletion due to ionization losses occurs at rather large distances only. The process of depletion is accompanied by a significant steepening of the temporal pulse form corresponding to the formation of a sharp ionization front of a medium density. The latter, in turn, becomes sharper, suffering an inverse influence of the steeping of a laser pulse temporal structure. The analysis of spatial and temporal evolution of magnitude of the laser pulse from steepening is carried out.

In result of numerical and analytical consideration is shown, that the essential part electrons, having been in area undercritical density, under action of arising forces is formed in clots and takes off for vacuum in a direction, different from normal to a normal of a surface in a narrow interval of corporal corners. The received results provide an opportunity of laser electronics acceleration at reflection USLP from a flat target.

In this work we consider a possibility of pulse (gamma) - source creation for atoms of nuclear isomers localized in a magnetic trap. It was shown, that in this case we can obtain a (gamma) -radiation pulse duration of 10²-10³ picosecond with a pulse energy about 10^-3.

Second harmonics intensity and spectra, emitted from solid Al target heated by obliquely incident p-polarized 1.5 ps Nd-laser pulse, are interpreted in the frame of 1D hydrodynamics model including resonance absorption, fast electron generation and transport and acceleration of ions. Second harmonics spectra reveal blue shift for laser intensity 10¹⁶ W/cm², while red shift is observed for laser intensity 10¹⁷ W/cm². It corresponds to a qualitative difference in the critical surface dynamic is observed in simulations. A good agreement of simulation result with experiment is observed for the lower intensity while possible explanations of certain discrepancies for the higher intensity are proposed.

On the PROGRESS laser facility the spectral and spatial characteristics of suprathermal particles extension in experiments with flat targets and picosecond duration of heating laser pulse are investigated. The opportunity to use multiframe pulse interferometry for visualization of spatial and power parameters of suprathermal particle extension alongside with traditional means of charged particle diagnostics with an irradiation of flat targets in an atmosphere of residual gas are considered. The basic part of laser radiation with energy up to 20 J and pulse duration 200 ps is directed to target chamber. A few parts of a heated laser pulse amplified and compressed with Raman backscattering compressor up to 10-20 ps with energy 20-30 mJ and wavelength 622 nm was used as optical diagnostic beam in multiframe interferometer. Series of experiments both with p and with the s-polarized radiation were carried out. On the basis of received interferograms the measurements of spectral parameters of fast particles by traditional methods with time-of-flight technique are carried out. This data are compared with spatial distribution of fast ions at picosecond laser-plasma experiments and laser intensity up to 10¹⁹ W/cm² on the PROGRESS-P laser.

Focusing of multiterawatt laser beams is of particular importance for super strong field experiments. The parameters of focusing system of 30-TW Nd: glass laser facility PROGRESS-P with chirped pulse amplification and result of experimental investigations of laser beam propagation through this system are presented. Near diffraction-limited beam quality is obtained at output laser amplifier chain by use of the low-thermal phosphate Nd:glass and high quality optical elements. Output 180 mm beam is compressed to 1.5 ps using two holographic gratings with dimensions 420 X 210 mm, injected in target chamber through the LiF-window with low nonlinear refractive index coefficient and focused to targets by means developed f/1.1 on-axis parabolic mirror with focal length of 200 mm. Over 50 percent energy is obtained in 6-7 micrometers focal spot in target chamber for low power beam. Determination of the focal spot dimensions for 10 TW beam from x-ray plasma image show that microspot diameter not exceeds 7 micrometers .

The problem of initiating of laser-induced damage (LID) and ultimate laser fluence for homogeneous and low-absorbing optical coating is considered. It is shown that nonlinear electrodynamic processes of formation of shock electromagnetic waves is the ultimate mechanisms of LID initiating in ideal coatings because of developing of super field instability resulting from field disruptions accompanying the shock waves. Theoretical model of formation of shock electromagnetic waves is presented. In particular, two necessary conditions for shock wave formation are obtained. Computer modeling is used to investigate dynamics of shock-wave developing. Influence of coating parameters upon blow-up field instability is investigated. It is proposed a new design of multilayers optical coatings: each layer should include microlayers with similar refractive indexes and gradually varying nonlinear refraction. Such microstructure excludes sharp jumps of nonlinear optical refraction which are critical for increasing of field- instability threshold.

Free-running generation performance of a flashlamp-pumped Cr:LiSAF rod are presented. Laser average powers of 14 W at 10 Hz repetition rate, total laser and slope efficiencies of 3.5 percent and 5.1 percent, respectively, have been achieved. the laser was tuned from 810 to 910 with only one pair of broad band mirrors and a birefringent filter in the cavity.

Chemisorbed films of octadecyltrichlorosilane (OTS) and ethyltrichlorosilane (ETS) at the interface calcium fluoriderair have been studied by vibrationally resonant IR pump IR-vis probe sum-frequency (SF) spectroscopy. Using a total internal reflection geometry, a signal enhancement of more than two orders of magnitude compared to the conventional setup is achieved. This enhancement in combination with two independently continuously tunable in- dielectric surfaces. A fast energy exchange between the CH₃-stretching modes detected by SF spectroscopy occurs within a few picoseconds. A two-exponential decay of the CH₃-stretching modes is observed: the energy relaxation is fast with time constants in the picosecond range, while the ground sate is repopulated in approximately 100ps. of a SF-active mode can be achieved, even if the pumped mode does not directly contribute to the SF spectrum. This weakening of the selection rules in IR pump IR-vis probe SF spectroscopy is demonstrated for the methylene stretching vibrations of OTS.

Novel ablation of wide band-gap materials such as fused quartz and GaN by multiwavelength excitation using a VUV-UV laser system is reviewed. Simultaneous irradiation of VUV and UV laser beams emitted form a VUV Raman laser presents great potential for precision from microfabrication of the materials. The mechanism and the role of VUV beams in this process are made clear on the basis of band structure. The advantages of this technique are discussed in comparison with the conventional single wavelength ablation. Furthermore, another novel ablation of glass materials using a conventional UV laser, referred to as 'laser-induced plasma assisted ablation (LIPAA)', is introduced. By LIPAA, a high quality micrograting structure is fabricated on fused quartz.

The ICF Programs in China have made significant progress in solid state laser technology development and advanced laser facility designing with multilabs' efforts in the past years. The eight-beam SG-II laser facility is expected to complete for a 4.8-kJ output at 1.05 micrometers and to operate for target experiments in a few months. A national project, SG-II laser facility, has been proposed to produce 60-kJ blue light for target physics experiments and is being conceptually designed. New laser technologies, including multipass amplification, large aperture plasma electrode switches, fast growth of KDP, laser glass with fewer platinum grains, long flash lamps and precision manufacturing of large optical components are being developed to meet the requirements of the SG-III Project. In addition, numerical simulations are being conducted for the optical design of the new facility. The Technical Integration Line of 4 by 2 segmented array as a prototype module of SG-II with a chamber for laser beams measurements will be first built in the next few years.

We present performance of PROGRESS Nd:glass laser facility which consists of a six beam phosphate Nd:glass laser, 30 TW PROGRESS-P picosecond YLF:Nd glass laser, which uses chirped pulse amplification technique and target chamber. PROGRESS-M laser is capable to focus simultaneously at 1,054 micrometers the energy of 1.5 kJ PROGRESS-1M laser. This laser with output rod amplifier 14 cm is the prolongation of one of the beam of the multi-beam laser. PROGRESS-P CPA laser uses YLF:Nd oscillator, single mode optical fiber, Nd:glass rod amplifiers with output diameter of 85 mm. At the output, the chirped pulse with energy about 45 J is compressed up to 1.4 ps in the single-pass compressor on two holographic gratings, which produces power of 22 TW.

A large volume excimer laser, HERCULES, has been successfully applied as pump for a soft x-ray plasma source. The laser pulse duration has been varied from the natural value of 120 ns down to 10 ns, reaching different emission spectra from the plasma which have resulted to be optimum for different applications of the plasm source itself. Some experimental results on the applications of the source to different fields are presented; the choice of the best laser parameters in relation to the applications of the plasma source are also discussed.

Here we are discussing the feasibility to produce a powerful thermonuclear neuron source on the basis of double pulses of KeF laser.

The spatial filters are used in Technique Integration Line, which has a multi-pass amplifier, not only to suppress parasitic high spatial frequency modes but also to provide places for inserting a light isolator and injecting the seed beam, and to relay image while the beam passes through the amplifiers several times. To fulfill these functions, the parameters of the spatial filters are optimized by calculations and analyzes with the consideration of avoiding the plasma blow-off effect and components demanding by ghost beam focus. The 'ghost beams' are calculated by ray tracing. A software was developed to evaluate the tolerance of the spatial filters and their components, and to align the whole system on computer simultaneously.

Technical Integration Line (TIL) is the full scale two-beam prototype for Shenguang-III laser facility. A four pass amplifier system with small aperture beam reverser has been designed as the main amplification stage for TIL, which will produce 1 kJ of UV radiation on the target from each beam in 1-3 nanoseconds shaped pulses. Two schemes were considered in the preliminary design, one of them employed only small aperture Pockels cell in the reverser, and the other used another larger plasma electrode Pockels cell in the main beam line. Simulated by a fast-running lumped-element computer code, the configuration of baseline scheme for TIL was settled. The basic requirements for optical elements were raised during simulation processing.

Numerical simulation of thermonuclear flash with isobaric ignitor for laser spherical targets with different dimensions and temperatures are performed and the target energy gain as a function of ignitor parameters is obtained. As a result the requirements for ignitor parameters are elaborated under which the spark ignition provides an essential increase in the gain as compared with volume ignition. Calculations are carried out with the use of TERA code based upon self-consistent solution for system of kinetic equations for thermonuclear particles and radiation, obtained by the Monte Carlo method, and of hydrodynamic equations.

The advantages of a high-power KrF laser system 'GARPUN' generating UV radiation of 248 nm wavelength, 100 J energy and 100 ns pulse duration for the production of megabar range ablation pressures are demonstrated. The scaling law for the pressure dependence on laser intensity reaching 5*10¹² W/cm² was established and compared with other wavelengths. High-pressure material investigations were carried out with the emphasis on a shock wave dynamics and equation of state studies. Pressure-induced transformation of the pyrolytic graphite into a diamond-like phase was observed for the first time in laser-target interactions.

Dye cell 'soft' diaphragms for apodization of powerful laser beams are investigated. A cell design with a meniscus lens spacer is proposed to compensate thermal phase distortions in the transmitted laser beam. laser shot-blasted 'soft' aperture technology is discussed. The obtained results have revealed a feasibility to create a wide-aperture nonlinear optical decoupling element - apodizer for application in powerful iodine, neodymium and excimer lasers.

Optically detected carrier dynamics in III/V semiconductor quantum well (QW) heterostructures perpendicular to the interfaces is studied. Photoluminescence emission originating form different semiconductor layers are recorded time-resolved to probe the carrier dynamics between these layers. High spatial and temporal resolution is obtained experimentally, partly even in the nm and sub-ps ranges, respectively. Using several specially tailored semiconductor heterostructures enable the following individual dynamic effects to be studied and separated: transport in extended unquantized layers, capture into the QWs, relaxation in the QWs, tunneling between the QWs and thermal re-emission from the QWs. These basic physical effects have to be studied and understood to design and implement modern high-speed semiconductor laser devices. AlGaInAs and GaInAsP heterostructures are compared with respect to interwell transfer efficiencies and problems in technological implementation. This paper proceeds from basic research to applications in high-speed laser devices.

The propagation of femtosecond light pulse in nonlinear medium is described by nonlinear Schrodinger equation with temporal derivation from nonlinear response. Properties of this equation are investigated and obtained invariants of the femtosecond pulse propagation in nonlinear medium. The transformation of this equation to a more convenient form is proposed. Various problems of nonlinear optics are considered with the aim of applying of proposed transformation. The transformation of Schrodinger equation allows creating of conservative difference schemes for computer simulation of an interaction of femtosecond laser pulse with matter. These schemes make soliton solution of nonlinear SChrodinger equation with temporal derivation from nonlinear response.

It is shown that an interaction of ultrashort optical pulse with a deep modulated 1D periodic structure with cubic nonlinearity is followed either by an optical switching, compression or reshaping of a reflected pulse depending on its duration, intensity and detuning of a carrier frequency from an edge of a forbidden gap. It is found out that a gap structure with a metal cover on a back edge possesses a considerably smaller intensity threshold to attain a compression at pulse reflection.

It is shown that the fast saturable absorber effect due to the Stark shift of the excitonic resonance in the quantum- confined semiconductor can contribute to ultra-short pulse formation and stabilize the pulses with extremely short duration at the below band-gap excitation, i.e. in the presence of the Stokes mismatch between gain band center and excitonic line. This mechanisms is strong enough to provide self-starting over the full region of the cavity stability.