The use of a cw diode-pumped Nd:YAG rod laser for industrial applications is investigated. The laser is pumped by water cooled high-power laser diode bars in a star-shaped transverse pumping configuration. An output power of 75 W is achieved with 240 W of pumping power, corresponding to 40% slope efficiency. Thermal lensing and birefringence of a laser rod with a diameter of 4 mm is investigated. High fundamental transverse mode and second harmonic efficiency is reported. A simple scalable concept for lasers with 10 W to 100 W output power is presented.

The 3 mJ output energy for Nd:YAG, 1.6 mJ for Nd:YVO₄ were obtained in free running mode. Above 170 kW peak power in 5.6 ns pulse duration was achieved in electrooptic Q- switched Nd:YVO₄ laser. The lower threshold, near diffraction limited output, shorter cavity length advantage Nd:YVO₄ for low energy, high pulse power applications.

A cw diode-pumped Nd:YVO₄ laser system was developed which is capable of delivering 10 W of average power at high repetition rates of more than 20 kHz. Longitudinally fiber- and simultaneous side-pumping is used for a compact, electrooptically Q-switched laser oscillator producing stable pulses with widths ranging from 5 to 15 ns, and a nearly Gaussian beam profile. The radiation of the oscillator is efficiently amplified by a small, longitudinally fiber- pumped double-pass amplifier.

The dynamics of passively Q-switched, diode-pumped solid-state lasers have been investigated on a rate equation basis. The importance of the absorption cross section of the saturable absorber material was discussed, and the relevant parameters of a passively Q-switched solid- state laser were evaluated. The theoretical calculations were used to optimize a longitudinally diode-pumped Nd:YLF laser which was Q-switched by Cr⁴⁺:YAG as a saturable absorber.

Laser operation in the 2 micrometers -wavelength range is reported. Two different crystals are studied: Y₂SiO₅ and SrY₄(SiO₄)₃O doped with 5% thulium. Microchip lasers with flat/flat monolithic cavity are operated at room temperature, with Ti:Sapphire laser pumping. Threshold as low as 130 mw of incident pump power and slope efficiency as high as 46% were obtained. The emission spectrum of such microchip lasers appears to be very wide (20 to 30 nm). Laser experiments with laser diode pumping are also reported.

The lamp pumped Cr:Tm:Ho:YAG laser, with slope efficiency about 2%, and up to 17 W average power was demonstrated. The output energy, average power, as well as M² parameter were investigated in dependence on temperature and cavity configuration for wide range of pump power levels. The optimized cavity with concave facets rod and flat mirrors enabled to shift stability range to 2 kW of pump power.

CW 2.12 micrometers YAG:Yb-Ho lamp pumped room temperature laser with the output power of 1 W is reported for the first time. The processes of energy transfer, creating the operating scheme of the laser, are studied.

In the frame of the rate equation model for 3 micrometers Erbium laser, working on the transition ⁴I_11/2 yields ⁴I_13/2, the role of two-ion and three-ion energy transfer processes is examined. It is shown that though two-ion processes can describe the main characteristics of three-micron generation, to explain experimental facts as 2.8 micrometers lasing of Er:YSGG pumped in the terminal laser level, the contribution of three-ion upconversion from ⁴I_13/2 should be considered. A quantitative estimation of this contribution for a Er(25%):YSGG laser, pumped at 1.533 micrometers , is tentatively performed.

Energy parameters for the erbium glass laser medium are calculated in the chosen model for the laser pump. The calculation results are compared with the experimental data. Stored energy extraction is experimentally measured.

We have constructed, theoretically described and studied characteristics of plane-parallel geometry KTP optical parametric oscillator for conversion Nd:YAG laser radiation into eye- safe region (1.57 micrometers ). 50% conversion efficiency and 12.5 mJ generation energy have been attained.

A oscillator amplifier configuration of laser has been designed and demonstrated using an oscillator with a single titanium sapphire rod in a pumping chamber in a close coupled configuration with a single linear flashlamp. The amplifier was of a similar design but used a pair of flashlamps. Currently, it has produced in excess of 3 J/pulse in the free-running scheme at a repetition rate of 5 Hz. Some applications of this type of tunable laser are considered.

Stable and high gain of U-violet laser pulses was achieved in Ce:YiLF₄ with nanosecond flash lamp pumping (nsFL)-`Soft' pump. it is due to neglectly low probability of two-step ionizations of Ce<sup>3+</sup> with nsFL pumping. Gain was not observed for this crystal under KrF-laser pumping-`Hard' pump. Two-step ionization of Ce³⁺ reduces of quantum yield emission of Ce³⁺ and prevents to population inversion 5D-4F of Ce³⁺ at laser pumping.

Single frequency operation of a diode pumped Er:YAG laser at 1.64 micrometers was achieved first time with a new type of halfmonolithic lasers in a cleaved coupled cavity (C3). A single frequency Er:YAG-Er:glass-sandwich laser in C3-design was realized as well. Single frequency operation of the Er:glass laser is also achieved with a thin metal film and a tilted Fabry-Perot etalon as mode selective elements. The tuning range of Er:glass can be extended up to 1560 nm by a special mirror coating. Eye safe erbium lasers are very important for different applications in optical communication and lidar techniques, e.g. due to their coincidence with the attenuation minimum of glass fibers at 1.55 micrometers (Er:Yb:glass laser) and with the methane absorption line at 1.64 micrometers (Er:YAG laser).

We investigated theoretically the influence of quantum amplitude noise of a CW single- frequency solid-state laser on frequency fluctuations. Numerical estimation was carried out for Nd:YAG laser giving the difference from the flat spectrum corresponding to the Schawlow- Townes limit.

We consider the properties of laser system which contains the slave pulsed Ti:sapphire oscillator with injection of a narrowband pulses from BBO optical parametric oscillator (OPO). Ti:sapphire laser and BBO OPO were pumped simultaneously by the second harmonic of the pulsed Q-switched Nd:YAG laser.

Examined praseodymium doped crystals with 1 at.% of Pr³⁺ ions for YAG and SrLaGa₃O₇ (SLGO) hosts were produced using Czochralski method. The luminescence for the range of 200 - 800 nm and absorption spectra for a wide range of 200 - 6000 nm, for Pr³⁺:YAG and Pr³⁺:SLGO crystals have been measured. It was stated that for praseodymium doped YAG and SLGO crystals, the strongest peaks of luminescence occur at 0.489 and 0.502 micrometers and the strongest peaks of absorption occur at 0.44 - 0.5 and 0.58 - 0.62 micrometers bands. A free-running laser emission of (lambda) equals 0.62 micrometers radiation for both types of crystals Pr:YAG and Pr:SLGO for two different transmissions of output mirrors have been obtained.

The various processes leading to loss of efficiency and to heating effects in YAG:Nd laser crystals are discussed. It is thus shown that there are several unavoidable intrinsic sources of loss such as the spectral inhomogeneities in the melt grown crystals and the concentration quenching of emission and these impose upper limit quantum efficiency function on the activator concentration. The estimations made within these models are in a good agreement with the data on quantum efficiency of emission or on fractional thermal loading.

The mutual static crystal field perturbations produced by near sensitizer and activator ions shift the energy levels and modify the radiative and energy transfer characteristics. The selective and discrete nature of these effects transforms the ensembles of sensitizer and activator ions into inhomogeneous systems and modify the spectral and temporal characteristics of emission from activator ions in sensitized laser crystals. These effects are exemplified for Cr³⁺ or Fe³⁺ sensitized emission of Tm³⁺:YAG.

Spectral data on Pr³⁺ ion in Czochralski grown GGG Gd₃Ga₅O₁₂) crystals are analyzed. Pr³⁺ spectra, investigated by high resolution absorption, site selective excitation and emission contain besides the main lines assigned to Pr³⁺ in dodecahedral c-sites, at least four other types of non-equivalent centers. Three satellites have been assigned to Pr³⁺ in dodecahedral c-sites perturbed by a non-stoichiometric defect, Gd³⁺ in octahedral sites, whose concentration was estimated from absorption. A reduction of local symmetry is observed from the spectra. It is connected with X-ray measurements that show forbidden {222} reflections in cubic ideal garnets, but with similar small intensities. Other lines are assigned to Pr³⁺(c)- Pr³⁺(c) near pairs, one of them showing a very strong quenching of ³P₀ emission. Some of the mechanisms of ³P₀ emission quenching and their influence on quantum efficiency are discussed.

Investigations of spectroscopic properties of yttrium-aluminium garnet Y₃Al₅O₁₂ (YAG) doped with Ce, Pr, Nd, Sm, Eu, Ho, Er, Tm, Yb ions and Nd:YAG, Nd:SrLaGa₃O₇, Nd:SrLaAlO₄, Nd:YVO₄, Nd:LiYF₄, Nd:PbMoO₄, Nd:LGS, Nd:GGG, Nd:SVAP monocrystals have been realized. Absorption spectra of the monocrystals in the range 200 nm divided by 20 micrometers and the luminescence spectra in the range 200 divided by 800 nm were determined. Except for Pr:YAG, Sm:YAG, Eu:YAG and Pr,Yb:YAG in all other materials an appearance of strong absorption bands in the range of 780 divided by 840 nm has been stated what enabled to carry out an efficiency analysis of selective pumping with the use of GaAlAs laser diodes.

An Yb,Nd-doped flashlamp pumped crystal laser for an average-power operation is discussed. Excitation transfers from Nd³⁺ to Yb³⁺ ions in garnet offer stored energies near 1 J/cm³, pulse repetition rate of 1 Hz.

Pump-induced probe beam deflection in an off-axis geometry is used to achieve simultaneous shaping and shortening of probe pulses. The first and the second harmonic of a Q-switched Nd:YAG laser served as a pump and probe wave respectively. Each pulse generated (super- Gaussian, sequences of two and three pulses) was of a reduced duration as compared to that of the incoming probe pulse.

The results of the numerical simulation of the laser beam quality changes after propagation through the passive and active optical systems with the linear and nonlinear aberrations are presented. The new algorithm for the calculation of the phase conjugation by steady-state SBS is developed. It is found that the parameter M² of the Stokes beam in the saturation regime is often nearly the same as that of the pump beam. The generation of short (approximately 1.5 nsec) pulses with energies exceeding 4 mJ has been obtained using passive Q-switching of the short (approximately 10 cm) resonator of Nd:YAG laser by GSGG:Cr,Nd crystals. After SBS-compression the pulses with approximately 120 psec duration and with energies of approximately 1 mJ have been obtained. Four-pass Nd:YAG amplifier amplifies the pulses to the energies approximately 500 mJ with the duration of pulses of approximately 170 psec. Experimentally obtained results are in good agreement with the mathematical modelling of short pulse generation and amplification.

Made up and investigated the prototype of lamp pumped, electro-optically Q-switched YAG:Nd laser, emitting approximately 1 J in one pulse with the pulse repetition rate 100 Hz. Laser schematics consists of master oscillator, double-pass preamplifier with SBS phase conjugate mirror and single pass final amplifier. Partial compensation of basic thermooptical distortions is done. It was found out that it is possible to eliminate astigmatism and diminish birefringence via interstage field relay and rotation of polarization plane in 90 degree(s) with simultaneous rotation in the same angle of the planes, containing the pumping lamps. It was found out, that the requirement of small jitter and phase conjugate compensation via SBS in liquid are in contradiction one with another due to the liquid breakdown. In the case of partial spectrum selection of master oscillator, the lower limit of average power of double pass amplifier with the liquid SBS mirror is caused by breakdown and the upper one--by phase conjugation aggravation due to distortions, exceeding the appropriate level.

Application of stimulated Brillouin scattering and backward stimulated Raman scattering to generate picosecond pulses at a wavelength of 1.54 micrometers has been investigated experimentally. Pulses with energies of 5 mJ, durations of about 20 ps and angular divergence near a diffractive limit have been obtained.

YSGG:Cr:Nd laser adaptive resonator, adjusted to laser rod thermooptical distortions by means of hydraulically controlled HR flexible mirror, was developed and investigated. Lasing with output power of 27 W and with more than twice improved divergence of 9 mrad was demonstrated during the thermal lens correction. A high optical quality metal flexible hydraulically-controlled HR mirror with a wide range of a focal length alteration is proposed to correct a laser rod thermal lens.

The performances of a two-rods super-Gaussian positive branch unstable resonator and one rod unstable resonator with amplifier stage for Nd:YAG solid-state lasers were investigated. A glass deformable pressure mirror was used for thermal lens compensation in the resonators.

An analytical expression for the locking range of two lasers was derived by a theoretical model describing the coherent coupling in a common cavity by means of an internal lens and a Fourier-filter. The theoretical predictions were experimentally proved using two diode- pumped solid-state lasers by thermally detuning one laser and analyzing the far field pattern in the locked and the unlocked state.

The modes of laser cavity with deflectors which perform the fast misalignment in two orthogonal planes are investigated. The possibility of beams formation with rotating around the cavity axis energy center of intensity distribution at mirror and beam direction is shown. The peculiarities of temporal and spatial structure of ultrashort modelocked pulses are analyzed.

The drive laser system of the photoelectric injector for free-electron laser (FEL) is described. This system consists of a 1.064 micrometers mode-locked Nd:YAG oscillator, a pulsed Nd:YAG amplifier chain, Pockels cell electrooptic shutter for selection of part of the amplifier pulse train, KTP frequency doubler and DKDP fourth harmonic generator are used. The bright electron beams required for high performance FEL's demand stringent specifications on drive laser output levels, beam quality, and stability. The design specifications, laser architecture, and operating performance are presented.

The process of fourth harmonic generation in multicascade laser installation is experimentally investigated. The operative correction of phase synchronism in nonlinear crystals permits to compensate an installation parameters drift and provides stable radiation conversion to the 4th harmonic with efficiency 0.4 divided by 0.5 at E₄ approximately 10 J.

The development of the Zn(Se,Te) graded contact scheme to p-ZnSe is found to be effective in supporting the room-temperature CW operation of blue-green (508 nm) laser diodes with a threshold voltage of about 5 volts. Factors contributing to device degradation are analyzed by electroluminescence and plan-view TEM imaging. Both the nucleation/growth of the extended structural defects and the presence of point defects within the active region are responsible for the observed degradation. The more recent exploratory effort on blue-green surface emitting lasers and deep blue (edge emitting) lasers will be reported. Surface emitting laser operation at room temperature at (lambda) equals 496 nm by pulsed optical injection has been demonstrated in a II-VI separate confinement heterostructure cavity. By increasing the energy gaps of the cladding, waveguiding, and quantum well layers, pulsed operation of a 460-nm edge-emitting laser at room temperature was also demonstrated. Electrically, p-type doping of ZnMgSSe is complicated by an apparent increase in the activation energy caused by a mechanism very much like that of the DX center in n-type III-V alloys. These factors must be addressed for II- VI light emitting devices to reach the deep blue part of the spectrum.

The scope of presented work was focused on laser diode optics destined to end pumped solid state lasers. The background and idea of quasi geometrical approach to laser beam propagation in real optical systems were presented. The criterion of laser optics quality based on concept of M² parameter was proposed and discussed. The appropriate software destined to evaluate laser beam propagation in real optical systems was developed. The results of computations were compared with results of intensity distributions measurements in the caustics regions for a few practically realized cases.

New fabrication technique of fiber endfaces microlenses (spherical, cylindrical, elliptical, hyperbolic, etc.) by grinding/polishing process has been developed. The coupling efficiency of laser diodes radiation in the range of 90 - 93% has been obtained. Fiber-diode-pumped Nd:GdVO₄ laser output power dependence on pump power diagram at the fiber output has been investigated.

Collimating and diverging cylindrical micro lenses with N.A. up to 0.60 fabricated by thermal silver ion exchange in a special designed glass type are reported. Cylindrical microlens arrays are fabricated by field assisted ion-exchange. Applications to fiber coupling as well as to diode bar collimation are discussed.

Active and passive UV filters for solid-state lasers are developed on the basis of Ce-doped silica gel glass. It is concluded that there are two types of optical center. It is assumed that they represent Ce(III) oxygen complexes whose nearest surrounding includes quadruply- charged (the first type) and triply-charged (the second type) ions of cerium.

Recent progress in design of diode-laser-pumped CW tunable narrowband mid-infrared sources based on difference-frequency generation (DFG) is addressed. Application of two such tunable sources to high-resolution spectroscopy and sensitive atmospheric trace detection of methane near 3.2 micrometers is reported. Methane detection limit in air of 12 ppb- m/(root)Hz is reported based upon the signal-to-noise ratio observed in the direct absorption spectra. Performance characteristics of these sources are examined including tuning range, phase matching bandwidth, output power, and amplitude stability. Applications of diode-laser-pumped CW tunable DFG may include atmospheric trace detection of several major hydrocarbons such as ethane, ethylene, and benzene, and toxic air pollutants such as carbon monoxide, nitric and nitrous oxide, sulfur dioxide, and methyl chloride.

A Nd:YAG Laser IntraCavity SpectroDetector (Nd:YAG LICSD) is described for sensoring small methane (CH₄) concentration in the atmosphere. The concentration detectability of the Nd:YAG LICSD of about 0.003 is experimentally demonstrated and of about 1 ppm is discussed.

Laser Induced Breakdown Spectroscopy is a new and powerful diagnostic technique for atomic and ionic pollutants detection. In situ and laboratory tests show the high sensitivity of this technique for metallic pollution detection in atmosphere, industrial exhausts and soil.

A compact neodymium laser with pulse repetition rate of 12.5 Hz and energy up to 8.8 J has been developed. Experiments have been done to evaluate the laser ignition of titanium carbide and aluminium phosphide synthesis reactions. The reliable ignition was obtained after 1 - 2 sec.

Method of drilling of transparent dielectrics by means metal wire was suggested and realized. The theoretical explanation of occurring processes was given. The optimal diameter of the wire suitable for drilling was selected and substantiated.