The use of a new method of interferometry of chirped pulse for precise remote measurement of lengths and velocities is proposed, evaluated and tested in experiments. The potentialities of the method in comparison with conventional methods are considered, and its possible applications are discussed.

Tunable femtosecond laser pulses in a large spectra range of 0.41 to 5.5 micrometers are used for noncollinear two-photon absorption in condensed matter. The spectral properties of two examples are discussed in detail: diamond of type IIa and neat water at room temperature. The generation of free carriers and results on the subsequent relaxation dynamics are presented.

The ultrafast relaxation of induced anisotropy in condensed media (organic liquids and their mixtures) is studied by forced light scattering using broadband dye laser radiation with variable spectral width. The influence of the finite spectral width of an exciting laser pulse on the observed relaxation dynamics of the investigated samples (so-called spectral-filter effect) is demonstrated for the first time in transient spectroscopy with incoherent light.

New nonlinear equations for the dynamics of spatial spectrum of a self-focusing monochromatic wave in a medium with cubic nonlinearity is derived in the nonparaxial approximation. The formation of optical beams with cross section on the order of a wavelength is considered. Backward self- reflection is found to be the fundamental cause for the limitation of optical self-focusing.

A nonlinear evolution equation describing an ultrashort optical pulse propagation under quasi-resonant condition is derived by the unitary transformation method. This method allowed us to obtain the terms which are not taken into account within the framework of the adiabatic following approximation. The analysis of the nonlinear evolution equation and example of its application are given.

One of the possible methods of realization of active medium with anomalously wide bandwidth has been described. Composite active medium, consisting of several laser active centers with overlapping gainbands in common resonator has been created. In this case gain contour has complex shape with local extremums. Method of numerical simulation of the formation dynamics of ultrashort pulse at passive mode locking in laser with arbitrary spectral gain contour has been performed. The main parameters for the generation of ultrashort pulse in a laser with a composite active medium are obtained and investigated. The conditions of realization of stationary regime in the form of ultrashort pulse generation with duration determined by combined gain bandwidth are calculated.

It has been proposed the design of mirrors for near IR femtosecond lasers with given pulse characteristics based on the III-V compound semiconductors using MBE-technologies with reproducible phase parameter due to precise control of the layer parameters. The designed structure of two-part multilayer mirror includes the bottom part with a great number of AlGaAs-pairs and the top several antireflection layers. The specified negative near-constant group delay dispersion can be realized at certain band of spectrum.

Stimulated Raman scattering (SRS) excited by picosecond pulses (3.5 - 4 ps) of a synchronously pumped dye laser has been studied in compressed methane, hydrogen and their mixture. Physical energetic SRS-efficiencies (corrected for the linear losses of the optical elements) up to about 55 - 60% and 35 - 37% for the generation of the first vibrational Stokes radiation were reached in methane at a pressure of 60 bar and at excitation wavelengths near 600 nm and 740 nm, respectively. SRS-efficiencies versus pump pulse energy, pressure of gas and temporal duration of laser pulses were studied at 600 nm in methane. A very rich spectrum of Raman lines (including some vibrational, vibrational-rotational and combination Raman lines) was observed in the mixture of methane (35 bar) and hydrogen (25 bar). The energy efficiency of SRS-conversion to the 1-st rotational Stokes Raman line of hydrogen reached about 20% in the mixture. In contrast, the 1-st vibrational Stokes components of hydrogen and methane were substantially suppressed in this mixture. Our measurements demonstrate that methane is one of the most suitable Raman media for obtaining effective SRS-generation especially at pico- and femtosecond excitation because of its suitable parameters controlling the SRS-process and that the mixtures of compressed gases are rather promising Raman media for extending the tuning range of pico- and femtosecond laser systems and for optimizing the efficiencies of SRS-conversion to the different Raman components.

Active mode-locking itself provides pulses not shorter than picoseconds. Nevertheless, this regime is useful for many laser systems including powerful ones where strict synchronization with external periodic signal is needed. Another growing field where active mode-locking is widely used is fiber laser systems. 30 years passed since D. Kuizenga and A. Siegman (K-S) developed their (present well- known) theoretical model for active mode-locking. Hence many other models have been published, all of them (including K- S) are not completely adequate for the real laser systems. That conclusion was pointed out by one of the authors for the gas, dye and solid-state lasers and presented in many publications and conference papers. In this paper we present results of successful numerical modeling for the mode-locked Ar-ion laser, which are in qualitative agreement with the experiment. Disagreement of the known models (or not revealed stuff from them) with the experiment can be formulated in such common items: (1) an optimum pulse position inside the temporal mode-locker window: dependence on the gain, mode-locker parameters; (2) phase characteristics (pulse position inside the mode-locker window); and (3) pulse amplitude and duration versus the mode-locker parameters.

An all-solid-state pulse-shaping system based on a single- frequency master oscillator, preamplifier, and aperture- coupled-stripline electrical waveform generator has been developed and implemented in the OMEGA laser fusion facility.

In development of a known method of an regenerative amplification of low-power picosecond pulses (the injection seeding method) its modification: the method of injection locking of master laser with the amplifying laser (laser with short-term resonance modulation of losses--STRML-laser) is offered. The use of the STRML-laser as the regenerative amplifier allows to lower a level of the laser-injector power on two-four order. For the neodymium laser with an output pulse energy 1 - 2 J this power can be lowered up to 1 W, and the reliable capture can be carried out with 5 W. It enables to realize the circuit of self-injection in the STRML-laser by adding a nonlinear passive modulator in a cavity. Thus at a beginning of linear stage it is possible to `sow' pulses resulting in generation of much more short on a comparison with realized in a STRML-regime with preservation of remaining positive qualities of this laser.

The results of the study of ultra-short pulse generation in continuous-wave Kerr-lens mode-locked (KLM) solid-state lasers with semiconductor saturable absorbers are presented. The issues of extremely short pulse generation are addressed in the frames of the theory that accounts for the coherent nature of the absorber-pulse interaction. We developed an analytical model that bases on the coupled generalized Landau-Ginzburg laser equation and Bloch equations for coherent absorber. We showed, that in the absence of KLM semiconductor absorber produces 2(pi) -non-soliton pulses of self-induced transparency, while the KLM provides an extremely short soliton generation, 2(pi) - and (pi) -sech- shaped soliton solutions and variable-squared chirped solutions have been found. It was shown, that the presence of KLM loosens the stability requirements for ultra-short pulse generation removing the limitation on the minimum modulation depth in absorber necessary for the pulse stabilization. An automodulation stability and self-starting ability analysis is presented.

There is considered formation and propagation of shock electromagnetic waves (SEW) of visible spectral range as possible nonlinear optical phenomenon taking place at laser intensities characteristic of femtosecond laser interaction with transparent solids. Main regularities of SHEW formation are studied on the basis of 1D model of plane-wave propagation in isotropic dielectric with nonlinear optical response. Special attention is paid to influence of color dispersion and absorption on SEW formation and propagation. Necessary conditions for appearing of SHEW are obtained, in particular, threshold amplitude is estimated. There is presented an model for numerical study of SHEW formation and propagation influenced by dispersion of linear and nonlinear pats of refractive index. Using the simulation, we studied dynamics of SHEW formation on several optical cycles near leading edge of femtosecond laser pulse propagating in transparent medium. Important observed features of SHEW are discussed.

During the interaction of picosecond laser pulse of intensity 5 X 10¹⁸ W/cm² with the target we observed a MeV energy proton beam, confined in a cone angle approximately 30 degree(s) and directed normal to the target surface. Laser conversion efficiency into fast ions energy (at the front side of the target) was approximately 1% (and near 5% at the rear). The simulations and optimization on ion acceleration is discussed here. The laser intensity being approximately 10¹⁹ W/cm², nuclear reactions proceed in the target, particularly resulting in production of the (gamma) -line radiation. In light materials irradiated by the laser beam the (gamma) -photon yield reaches 10^-4 number of fast ions. For nuclear excitation we used also X-ray pump from laser plasma to illuminate film mixture of KBr and Rb⁸⁴. Near 10⁴, 200 Kev decay (gamma) -photons from excited isomer nuclei can be produced per laser shot.

Two sets of computer results are discussed. By means of a 2D Maxwell-Vlasov coupling code, the generation of MeV-range electrons and ions is addressed as well as the subsequent X- ray production and neutron production provided by post- processing the fast particle distribution. With a 3D MHD- fluid target-fast beam coupling code, the propagation of electrons in dense matter is discussed, with emphasis on the target heating.

The protons with the energy up to 10 MeV accelerated in the forward direction from the thin Mylar film by relativistically intense 10 TW, 400 fs laser pulse have been observed. When a deuterated polystyrene was deposited on the front surface of the film and a boron sample was placed behind the target the production of 10⁵ atoms of positron active isotope ¹¹C from the reaction ¹⁰B(d,n)¹¹C have been measured. The activation results suggest that ions (protons and deuterons) were accelerated from the front surface of the target.

Upon the interaction of an ultra intense laser pulse with a solid target, generated fast electrons can produce MeV ions from laser plasmas. These fast ions can be used in different applications ranging from ion implantation to nuclear reaction stimulation. The most important point is the efficiency of this fast ion production. We analyze--with help of an analytical model and PIC code simulations--the different acceleration mechanisms and compare the efficiency of electrostatic ion acceleration, at the front and rear of a foil target, the ponderomotive mechanism and acceleration by the shock wave in detail. The optimal plasma density distribution, shaped by laser prepulse, is found.

The light scattered backward from a target illuminated by ultra intense laser pulses carries important information about the nonlinear laser plasma interaction. We analyze the possibility of using this information with the help of developed analytical model and PIC simulations. The spectrum of scattered light is shown to be shifted, to be broadened and to be modulated, in comparison with the initial laser spectrum.

An interaction of a super strong linear-polarized electromagnetic wave with a dense plasma layer is investigated with the help of a self-consistent method of the analysis. It is shown that at falling a powerful harmonic wave at thin plasma layer the reflected field can be in the form of ultrashort pulses of radiation with amplitude considerably larger than an amplitude of an incident wave. A process of interaction of a plasma layer with a standing electromagnetic wave is considered also and a generalization of classical results about character of an electron motion in an electromagnetic field is obtained for a case of a strong field and large radiation friction. In a strong field a minimum of an effective potential splits into two new that results in violation of mirror symmetry of plasma layer radiation.

Back reflection of short, intense laser pulses at oblique incidence on solid targets is explained with a model where a periodic electron density modulation acts as a diffraction grating. The pump and reflected electromagnetic waves drive through the ponderomotive force the grating and the overall system becomes parametrically unstable. The basic equations governing this system are given. A linearized stability analysis yields the instability growth rate for a homogeneous plasma and the convective gain coefficients for the inhomogeneous case. The results support the feasibility of the suggested mechanism. An absolute instability is predicted to set on at a typical threshold intensity 10¹⁶ W/cm², laser pulse length 100 fs, and spot size 30 micrometers . The instability is shown to saturate at a level of a few percent, because the higher harmonics in the electron density modulation turn the diffraction more diffuse thus reducing both the sustaining ponderomotive force and the back reflection coefficient.

High-density plasmas created near a solid surface by a femtosecond laser pulse emit ultrashort x-ray pulses that are synchronized to the laser pulse. In the first part of this paper, the spectral and temporal properties of the x- ray emitted from plasma created on aluminum film by a femtosecond laser pulse are shown. The minimum pulse duration was < 3 ps as measured by an x-ray streak camera. The energy conversion efficiency, from laser pulse into soft x-ray at 14 +/- 0.05 nm, was 10^-6 - 10^-5. More than a 30-fold enhancement in soft x-ray emission was achieved by fabricating an array of nanoholes on an alumina surface. In the latter half, we demonstrate time-resolved absorption measurement in the soft x-ray region by means of pump-probe spectroscopy. Using a 10-ps x-ray pulse, we measured time-resolved absorption of optically-pumped silicon near its L^II,III edge. We found that laser-pulse irradiation caused a more than 10% increase in soft x-ray absorption near the edge, which means that the transition of electrons in inner shells was rapidly modulated by excitation of valence electrons. The absorption change recovered within 20 ps.

The Langmuir probe was used to study erosion plume resulting from ablation of a tantalum target in vacuum with excimer laser (308 nm) radiation. The spatial and temporal dependencies of electron and ion probe currents were obtained in real time. Relying upon a series of dependencies of electron probe currents on the value of probe potential, electron temperature of different plume regions was taken at various distances from the target. It was established that the plume electron temperature is non-uniform. The ion concentration in the plume determined at various distances from the target.

A production of large amount of ions with low temperature (less than 100 eV), low momentum spread and narrowed charge state distribution by petawatt-class short-pulse laser is under consideration. Residual ion energy as the least unavoidable ion energy after ionization of gases by a short intense laser pulse is calculated as a function of laser pulse parameters. Electron thermal energy coupling to the ions is estimated taking into account a multi-group structure of free electrons produced by optical field ionization.

Suppression of a large-angle stimulated Raman scattering (LA-SRS) of a short modulated (two-frequency) laser pulse in a transparent plasma in the presence of a linear long- wavelength electron plasma wave (LW EPW) having relativistic phase velocity is considered under the conditions of weak and strong coupling. The laser spectrum includes two components with a frequency shift equal to the frequency of the LW EPW. The mutual influence of different spectral components of a laser on the SRS under a given angle in the presence of the LW EPW is examined.

By means of Monte-Carlo modeling of thermonuclear (TN) burn wave propagation in isochoric spherical laser deuterium- tritium targets criteria of fast ignition are elaborated and corresponding energy gain is evaluated. It is shown that the target TN burning is independent on ignitor presence if the ignitor areal density and temperature are lower than the critical ones. In the opposite case TN flash results in effective burning with the gain G approximately 10³, and the TN energy release is practically independent on the further increase of ignitor parameters. The critical ignitor parameters are calculated for targets with different parameters of main fuel. The overcritical target gain is practically independent on ignition origin and may be evaluated with a good accuracy by the simple asymptotic expression. It is shown that the energy coupled to ignitor with critical ignitor parameters tends to some minimum value in the limit of small ignitor mass. The corresponding values of energy are obtained as a function of the temperature of the main fuel. Under these optimum ignition conditions the parameters of extra laser pulse are evaluated taking into account the fast ions energy transport mechanism.

Joint theory of gamma-generation (GG) and radiation-heat regime (GG&RH) in active medium (AM) of (gamma) -laser (GL) is applied for the analyses of total world experience in the GL-problem in order to choose those nuclei-candidates, active media, GL-schemes which are indeed actual for the GL- creation. The classification of GL over a degree of the `comfortable conditions' for the GG is given. The GL-schemes could be `residential (Rsd)' (creation of excited laser- active nuclei, ELAN, from its parents directly in the site of AM) or `nonresidential (Nrsd)' (creation of ELAN out off the AM). It has been turned out that all `residential' part of the world experience does not fit for the realization of GL and can be considered only as a museum-piece. Any Rsd AM on the short-lived isomers must be inevitably blasted before the beginning of the GG. That `museum' part includes a lot of ideas: GG on long-lived isomers; line narrowing by radio- frequency or optical fields; creation of (gamma) -gain in the inversion less mixture of the excited and de-excited nuclei (amplification without inversion); super-dilution of work- nuclei in a matrix via multi wave Borrman effect; non- Moessbauer active media in plasma, gas or beam with its optical laser cooling, a lot of schemes (one-stage, two- stage, two-phase, two-step, two-photon, etc.). The exception could be only Rsd GL pumped by another GL. But the Nrsd part of world experience had stood yet all strict tests of that joint theory.

The SPTEN-(gamma) -laser's development leads to the essentially new principles for the effective converting of the nuclear radiation (neutrons, gamma, etc.) into the well controlling and focusing broad formatted atomic (ionic, molecular, etc.) beams which are fit for the creation of the active medium of the (gamma) -laser and for the other aims, e.g., for the acceleration by many orders of the selection of atoms, molecules, isotopes, isomers, radionuclides, for high precision methods in the spectroscopy-chromatography of the macromolecules, etc. The appropriate Multi Beam Emitter systems, MBE, are based on the dividing of the broad formatted beam of nuclei into a big amount approximately 10⁵ - 10⁹ of the collinear microbeams with use of the especial deeply engraved gratings together with ad hoc ion and laser optics. MBE will be realized in a non-(gamma) - laser sphere before the first direct (gamma) -lasing demonstration experiments.

Joint theory of gamma-generation and radiation-heat regime in active medium of (gamma) -laser (GL) was created and applied for the analyses of the total world experience in the GL-problem in order to choose those nuclei-candidates, active media, GL-schemes which are indeed actual for the GL- creation.

The hosts and nuclei-candidates (mass approximately 46 - 243, transition energy approximately 1 - 200 keV, decay's time 10^-7 - 10⁺² s) for gamma-laser (GL) realization are represented over Mendeleev Table. The choice of active media (nuclei-candidates, hosts) for GL is based on the joint theory of (gamma) -generation and radiation-heat regime which accounts a big complex of hindrances against GL and thus discards many tentative candidates. Nuclei- candidates are screened at the analyzing of data banks for nuclear transitions. Chosen candidates (approximately 20) could be used due to author's method SPTEN (Soft Prompt Transplantation of Excited Nuclei). The discarded tentative nuclei (approximately 80) with the life-times 10^-6 - 10⁺² are represented too. All analyzed long-lived (approximately 0.5 - 10⁺² s) isomers are turned to be not fit for GL without use of very strong multi-wave Borrman effect even at the supposition of natural line's width. The application of the revealed candidates in two different (gamma) -laser's categories (residential and non- residential) is discussed.