This PDF file contains the front matter associated with SPIE Proceedings Volume 6610, including the Title Page, Copyright information, Table of Contents, Introduction (if any), and the Conference Committee listing.

Dynamics of the Q-switched microchip lasers pulse was investigated in experiment with high space and time resolution. It was found that spatial dynamics of the YAG:Nd³⁺/YAG:Cr⁴⁺ microchip laser emission could not be described by traditional formalism of transverse cavity modes. An alternative theoretical approach based on solution of the Maxwell scalar wave equation is presented. In our model we take into account the D_2d local symmetry of the Cr⁴⁺ ions and the corresponding two types of saturable transitions.

Previously we carried out experiments with diode-side-pumped Nd ³⁺:YAG rod lasers with varies configurations of pumping module. All the important output laser characteristics -free-running (FR) and Q-switched (QS) pulse energy, slope and light-to light efficiency, beam divergence were investigated as a functions of diodes parameters, pumping module and a rod geometry, neodymium concentration and resonator configuration. In result of this study we determined an optimal pumping module and resonator parameters witch provide the most effective laser operation. To achieve sufficiently high effective transmission from laser diodes (LD) into a rod we used multy-sectioned pumping modules with four- and eightfold symmetry in which LD's were mounted close-coupled to an active element (AE) (Fig.1 a, b). Really we realized laser free-running operation with slope efficiency of 55% in case of eightfold module geometry and of 45% in case of fourfold one. These results were achieved thanks to high exciting emission density obtained near the central axes of a rod. The same time as a visualization of spontaneous emission showed spatial distribution of inversed population was very nonuniform and it should be a reason of low quality of output beam. Further experimental study of Nd³⁺:YAG 5-mm-rod laser output in far field showed the possibility to decrease sufficiently a beam divergence of about 2-3 times within negligible losing of slope efficiency despite on gain nonuniformity. This result evidenced that output laser emission spatial distribution in far field depended mainly on the resonator configuration and the slope and the overall efficiencies mainly depended on overlap of the beam and the gain distributions.

A robust technique for achievement 1 GW output power at O64 nm by amplifying the radiation of diode pumped YAG:Nd⁺³/YAG:Cr⁺⁴ microchip-laser in flash lamp pumped amplifier is demonstrated. Compact hybrid laser system with diode pumped microchip master oscillator and two-pass flash lamp pumped amplifier with 300 ps pulse dutation and 300 mJ output energy operating at repetition rate up to 50 Hz is developed. Features of the laser system design are described.

Output pulse energy of 300 J for a pulse duration of i-I .5 ns has been achieved in a six-stage neodymium phosphate glass amplifier. A multistage spatial filter based on an pin hole line provides an aperture filling factor of 0.8 at the laser output. As a result, stored energy has efficiently been extracted, and power elements of the system have been accommodated on a single optical table. The energy efficiency of radiation conversion to the second harmonic is 55%. The laser is synchronized with a cw femtosecond laser with accuracy 50 ns and is intended for pumping of a chirped-pulse optical parametric amplifier.

Hybrid laser medium on the base of the Yb:YVO4 and Yb:YAG (and Yb:KYW) crystals with overlapping broadband gain contours in common cavity was experimentally analyzed. On the absorption and fluorescence data at liquid helium temperature, excited states lifetimes the energy of electronic levels of ytterbium in vanadate crystalline hosts were calculated and the lasing parameters of broadband transitions of doped ions were studied. It has been shown that, this way of forming of the stationary regime of ultrashort pulses generation with duration in accordance with combined gain bandwidth in the laser with hybrid active medium is perspective.

Experimentally proved that in laser on YAG:Nd³⁺ with nonlinear transparency absorber(NTA) by the level of pump, that is close to threshold, and by the focus of intercavity radiation in cell with NTA, auto stabilization of generation happens. For all that the reproduction of singles in axial period picosecond pulses achieved the level of 100%.

A passive Q-switching of 2.94-μm Er:YAG laser has been demonstrated using Fe²⁺:ZnSe single crystal saturable absorber. A giant pulse width ofabout 35 ns and output energy up to 30 mJ in fundamental mode were obtained.

Pulsed lasing ofthe Fe²⁺:ZnSe single crystal was demonstrated at room temperature. The laser action centered at 4.4 μm with pulse energies up to 1.4 mJ and an input energy slope efficiency of 11% was obtained vith a 2.94 μm Q-switched Er:YAG pump laser. Continuous tuning from 3.9 to 5.1 μm was demonstrated.

Presented in the work are the results of the development of a new combined CW ring single-frequency laser with universal design that allows efficient use as the active medium of both a Ti:Sapphire crystal and a dye jet. For the first time such combination has been implemented in a horizontal resonator configuration that offers an improvement of stability in the position of optical elements and more convenient operation. The short-term line width without the frequency stabilisation is less than 5 MHz (Ti:Sapphire) and < 10 MHz (Dye); with the frequency stabilisation to a specially designed thermo-stabilised reference interferometer with high finesse, the line width is less than 10 kHz (Ti:Sapphire) and 90 kHz (Dye), output frequency drift being less than 25 MHz/hour. The total working spectral range of the combined laser stretches from 550 to 1000 nm (550-770 nm for the Dye and 695-1000 nm for Ti:Sapphire) when pumped with 532/515-nm radiation. The maximum output power with a 10-W pump exceeds 2 W for the Ti:Sapphire configuration and is > 1 .5 W for the Dye one.

Scanning Raman lidar employed for automatic remote airborne prospecting, detection and identification the impurity gas and condensed components in ground layers of an atmosphere and coastal water areas is developed. The small-sized prototype of onboard scanning Raman lidar as the gas analyzer have been manufactured and tested in real conditions of transcontinental gas pipeline. Minimal concentrations of methane outflow of 6 ppm and of hydrogen suiphide one of 2 ppm are remotely measured in natural flight conditions.

Compact Yb-doped fiber laser (YDFL) based on tunable fiber Bragg grating (FBG) with 6 W output power and 45 nm tuning range around 1080 nm has been developed and studied. The laser output power and its spectral width (-0. 15 nm) do not change significantly at the tuning, while the FBG reflection coefficient is slightly increasing with an increase in FBG compression. It has been shown that such increase is reasoned by stress-induced changes in FBG's refractiveindex modulation amplitude.

We have investigated various operation regimes and resonator designs of the diode-pumped Yb³⁺-doped fiber laser, containing acoustooptic filter and modulator inside the resonator. To imbed the polarization sensitive acoustooptic tunable spectral filter into the polarization non-maintaining resonator, based on an isotropic single-mode fiber, without 3db polarization losses, CaCO₃ single-crystal non-dispersive polarization splitter was applied. By utilizing special designed laser resonator with acoustooptic filter and modulator inside, there were obtained stable smooth bell-shaped pulses, their duration depending on the resonator traveling time and their repetition rate being determined exclusively by the outer generator, controlling the acoustooptic modulator. More than 20nm acoustooptic tuning band of pulsed Yb^3-doped fiber laser radiation and 100nm tuning of CW one were obtained without polarization losses. 30W stable average power was reached through the two-stage amplification, using Yb³⁺-doped fiber and 14μm MFD W-fiber. For the sake of improving the laser cutting resolution we have investigated the possibility ofthe effective Second Harmonic Generation ofthis pulsed Yb³⁺-doped fiber laser radiation. 4W stable output average Second Harmonic power was obtained through the Second Harmonic Generation along the X-axis of the KTP crystal, further increasing of Second Harmonic power being limited by the thermal self-focusing of the Second Harmonic radiation, resulted in crystal damage.

We report a new stochastic model for studying the polarization-dependent gain and gain fluctuations in Raman fiber amplifiers with randomly varying birefringence as a function of the pump state of polarization and the polarization mode dispersion parameter. Based on the presented model and our previous experimental data for polarization dependent gain we develop a new experimental technique for birefringence correlation length measurement.

Faraday isolators with low heat release are created for high average power lasers. The heat release is reduced either by shortening the optical element (due to cooling to nitrogen temperatures or use of superconducting solenoids) or by employing non-traditional magneto-optical media with better thermo-optical properties. It is shown that the suggested ways make it possible to create a Faraday isolator for 100kW average power.

Large-aperture Faraday isolators with compensation of thermally induced polarization and phase distortions of highpower laser radiation have been studied experimentally. The degree of isolation is considerably increased up to 24-26 dB at 10-750 W power for one Faraday isolator and up to 42 dB at 10-200 W power for another Faraday isolator and is limited by the quality of TGG crystals. Phase distortions are also considerably reduced.

We describe spatial filters used in an Nd:glass laser with an output pulse energy up to 300 J and a pulse duration of 1 ns. This laser is designed for pumping of a chirped pulse parametric amplifier. We present data required to choose a shape and diameter of spatial filter lens, taking into account aberrations caused by spherical surfaces. Design features of spatial filters and the procedure of them adjustment are discussed in details.

The problems ofcreation the new media for solid state lasers of UV and VUV region are considered. The possibility to widen of choice of laser's media for region from 120 to 350 nm are reported. The possibles to create UV and vUv solid state lasers are discussed. This report is review on materials ourselves works and literature's data.

In the work, the results of the investigations of processes of non radiative energy transfer between ions Yb³⁺ and Trn³⁺ in silica-alumina fibers are presented. It was discovered that the interaction between ions Yb³⁺ and Tm³⁺ is described within the framework of the Ferster's law for the case of dipole-dipole interaction mechanism. The microparameter of interaction C_{daY rightwards arrow Tm} is 1.56 · 10^-39 cm⁶sec^-1.

Crystal BaY₂F₈ represents the big interest as the perspective active media for lasers ultra-violet (UV) and vacuumultra- violet (VUV) regions. For the decision of problems with solarization this media and a choice of sources pump it is offered to use up-conversion mechanisms pump with activators from rare-earth elements (RE). We have developed technology of grown of oriented monocrystals BaY₂F₈, have defined influence of orientation on growth rate and quality ofthe received monocrystals.

We report a new experimental and theoretical characterization of high concentration erbium doped silica fibers. Applying a pair-correlation function of erbium ions that is known from x-ray absorption fine structure spectroscopy, we develop a new statistical model of migration-assisted upconversion in erbium doped fibers. We find that the new model provides accurate fitting to our experimental data for the upconversion coefficient as a function of the metastable level population.

The NaTi₂(P0₄)₃ crystals were synthesised and their crystal structure and luminescence properties were investigated. Two luminescence bands in green-orange and red spectral regions have been observed. Properties ofthe red emission of the NaTi₂(P0₄)₃ crystals were investigated. Cumulative spectral data and their analysis have allowed to assign the red band emission to luminescence ofthe Ti³⁺ ions, those are formed in the NaTi₂(P0₄)₃ crystals during growth.

We have studied the effect of strong statistical dispersion of thermal lensing in laser ceramics. This effect is specific to ceramics and has no analogues either in glasses or crystals. The consequence of this effect is a spatial phase modulation with a characteristic size ofthe order ofa grain size.

Dependences of energy damage thresholds on radiation parameters and geometry for KGSS 0180 phosphate neodymium glass have been studied. Laser-induced damage threshold dependences on the pulse duration for the range of 1.5-20 ns for KGCC 0180 and K8 glasses are: ε_kgss = 16 τ^1/2 ε^K8 = 18 τ^1/2(J/cm², when τ is in nanoseconds). Damage thresholds for the entrance and exit surfaces of KGSS 0180 glass samples have been measured when the samples were irradiated by a P-polarized beam at a Brewster's angle: ε_ent ≈ 48 J/cm²; ε_ex J/cm². As has been found out, the threshold energy density of the beam in the case of Brewster's incidence to the exit surface of the sample is almost 1.5 times lower than in the case of a normal incidence. Testing techniques for detection of platinum micro-inclusions in the laser glass have been developed. The energy threshold for Pt-inclusions explosion has been determined at ε_tr ≈ 2.5 J/cm² under laser pulse duration of 7 ns. Over 70 KGSS 0180 glass samples have been tested. It has been shown that platinum-induced damage was absent only in 25% of glass melts out of the entire tested amount. An averaged concentration of inclusions was N_pt ~ 5 liter^-1. Concentration of micro-inclusions in the last KGSS 0180 batch (2006 year) is ~ 1 liter^-1.

Presented are the results of experimental investigations of a resonant doubler of CW radiation frequency that uses a novel non-linear optical crystal BIBO. For the first time by using this crystal in an external resonator a stable singlefrequency generation of the second-harmonic radiation was achieved with the output power of 270 mW at the wavelength of 425 nm. Conversion efficiency is as high as 36%. Generation instabilities were observed at second harmonic power higher than 300 mW inside the doubler cavity.

Demonstrated for the first time is automatic quasi-smooth scanning of an resonant frequency doubler synchronously with the frequency of a CW auto-scanned Ti:Sapphire laser within a 1-THz frequency range, which is limited only by the spectral width of non-linear crystal phase matching.

Possibility of high intense second harmonic formation with beam profile and pulse shape, which are similar the Gaussian ones, under the cascading SHG with taking into account cubic nonlinear response of medium is shown. Laser pulse on doubling frequency has intensity that is comparable or greater than the one of basic harmonic. The duration of second harmonic pulse can be many times less than the first harmonic pulse duration. We take into account dispersion and diffraction of laser pulses and group velocity mismatching.

The operation of picosecond synchronously intracavity pumped optical parametric oscillator (OPO) is reported. Singly resonant OPO is based on a Brewster cut single grating periodically poled magnesium doped lithium niobate crystal(MgO:PPLN) pumped inside the resonator of a diode pumped passively mode-locked Nd:YVO₄ laser. Continuously mode-locked operation was achieved, and tuning of signal wave wavelength in the range 1531 - 1554nm was observed for PPLN temperature variation from 31 to 55 ° C. Spectral width of the generated radiation was 2 nm.

The process of JR-object visualization by nonlinear optical interaction is presented in the work. The conditions of phase synchronism are very important factor of efficiency of optical transformations. The theoretical account and the experimental results on transformation of broadband radiation focused in nonlinear crystals are given. All accounts and experiment are executed for oo→e interaction. In the same way the electrooptical effect is described as a non-linear transformation.

It was observed the split of the laser beam by nonlinear barium sodium niobate crystals at excitation of samples of He- Ne laser (630.0 nm). The results are compared with earlier obtained focusing argon ion laser beam by this crystal and connected to studies of x-ray crystallography with emphasis upon behavior of microdomain structure.

Partially ordered domain structure is detected for the first time in non-ferroelectric strontium tetraborate crystal via nonlinear diffraction. Domains have the form of sheets with the domain walls oriented perpendicularly to the α crystallographic axis. The thickness of domains is the random quantity; the spatial Fourier spectrum of the nonlinear susceptibility protrudes from π/6 to π/0.2 μm^-1.

A set of rare-earth (RE) noncentrosymmetric (NCS) binary and ternary oxides has been compiled in tables including nonlinear optical (NLO) properties, structure and shortest chemical bond lengths, L(E-O) <200 pm < L(M-O). The field of such crystals has been defined on the plane of L(E,M-O) bond lengths as a rosette of two ellipses of << acentricity >>. The areas are specified for creation of laser active RE-elements and compared for different combination of such elements as La³⁺-Nd³⁺, Y³⁺-Nd³⁺, Y³⁺-Yb³⁺, where La³⁺, Y³⁺-contained oxides are laser matrix, and Nd³⁺, Yb³⁺ are suitable active constituents of self activated (SA) and self frequency doubling solid state lasers (SFD-SSL). It is note that crystals with cubic structure, and crystals are positioned out the << acentricity >> rosette are not useful for creation of the SFD-SSL.

We study the effects of the induced third-order nonlinearity on backward second-harmonic generation in Penodically Poled Lithium Niobate (PPLN). We show that self-phase and cross-phase modulation terms induced by a proper engineering of the domain length can compete with intrinsic quadratic nonlinearity enriching the dynamics of the system. In particular it allows for self oscillation even with vanishing second-harmonic input.