The correct conditions for measuring the luminescence intensities in fi laments formed by the action of femtosecond laser pulses were found for lithium fluoride crystals. The determined conditions ensured that the measured intensities were proportional to the concentrations of luminescent color centers created in the crystals by the laser radiation and allowed conclusions to be drawn about the processes occurring in the filaments. Near-cluster color centers were found, indicating the presence of nanosized clusters in all areas of the fi laments.

The photoluminescence of lithium fluoride nanocrystals and crystals placed on the anode of an atmospheric-pressure glow discharge in helium and exposed to the discharge components was studied. The luminescence spectra showed that color centers with new properties inherent to near-cluster centers were formed in unannealed nanocrystals after exposure to the discharge. However, the conditions necessary for formation of near-cluster centers were eliminated upon annealing of the nanocrystals. These necessary conditions were partially restored when annealed nanocrystals were exposed to the discharge. This opened new possibilities for elucidating the processes and mechanisms of formation of centers with new properties.

Thermoluminescence spectra in the temperature range 80–300 K were compared for lithium fluoride nanocrystals and crystals. Four and one band were observed in the spectra of nanocrystals and crystals, respectively. Thermoluminescence intensities integrated over the spectrum and temperature range were measured for two types of lithium fluoride samples in one of which radiation color centers with new properties could form and in the other of which they could not form. The intensity was found to be significantly higher in samples of the first type.

It has been established that in lithium fluoride crystals, subjected to pre-irradiation thermal shocks or compression, intrinsic point defects with new properties different from the known properties of the usual defects of the same composition are formed as a result of irradiation. The obtained new properties are similar to those for radiation-induced defects that were previously registered in nanocrystals and called near-cluster defects. It is shown that the combination of pre-irradiation heating and compression of a crystal increases the ratio of the concentrations of formed near-cluster and usual defects.

It is shown that the ratio of concentrations of near-cluster and conventional radiation color centers increases in magnesium fluoride nanocrystals in the case when the manufactured samples before irradiation are kept for some time at a temperature higher than the anion vacancies mobility temperature. Such preirradiation heat exposure on lithium fluoride nanocrystals leads to the formation of near-cluster aggregation color centers during radiation exposure of the samples. It is established that differences in pre-irradiation thermal effects on the samples affect the kinetic of concentration growth of aggregate near-cluster centers in the post-radiation period. Conclusions are made about the mechanism and processes of nanoclusters formation in the samples, as well as about the defects involved in the formation.

The luminescence and absorption properties of LiF, NaF and MgF2 nanocrystals containing radiation-induced point defects with new properties are investigated. The influence of temperature, at which nanocrystals are maintained after their manufacture, on the efficiency and kinetics of such defects formation is examined. For LiF samples, the activation energy of fotmation processes is determined. X-ray diffraction reflections are compared for LiF nanocrystals, unannealed and annealed after fabrication, unannealed and irradiated with γ-rays or electrons, as well as those manufactured by fragmentation of an irradiated crystal plate. Conclusions are drawn about the processes of self-assembled nanostructures formation, the presence of which is a prerequisite for the creation of radiation-induced point defects with new properties.

The ratio of concentrations of nearcluster and conventional color centers increases in magnesium fluoride nanocrystals when prepared samples are maintained for some time before irradiation at a temperature higher than the temperature for mobility of the anion vacancies. Such pre-irradiation treatment of lithium fluoride nanocrystals leads to the formation of near-cluster aggregation of color centers during radiation exposure of the samples. Differences in the preirradiation temperature regimes of the samples affect the kinetics of the growth of the concentration of aggregate nearcluster centers in the post-radiation period. Conclusions are drawn concerning the mechanism and processes of nanocluster formation in the samples as well as the defects involved in their formation.

The formation features of the single-frequency unidirectional monopulse lasing mode of a Nd:YAG laser with a triple-mirror ring cavity and a side diode-pump with injection of external narrow-band optical radiation into the cavity are studied. The asymmetric layout of the intracavity elements relative to the output mirror and depolarization effects in them cause the energy and polarization of the monopulse Nd:YAG ring laser to differ depending on the input direction (clockwise or counterclockwise) of the injected radiation. The difference in the output characteristics of the single-frequency unidirectional monopulse Nd:YAG ring laser is most evident for a change from active to passive Q-switching.

The formation features of the regime of single-frequency unidirectional monopulse lasing of Nd:YAG laser with a triple-mirror ring cavity and a side diode-pump under the condition of injection of external narrow-band optical radiation into the resonator are studied. It is experimentally shown that the asymmetrical layout of the intracavity elements relative to the laser output mirror and the depolarization effects in these elements lead to a difference in the energy and polarization of the monopulse Nd:YAG ring laser depending on the direction (clockwise or anticlockwise) of the input of the injected radiation. The difference in the output characteristics of the single-frequency unidirectional monopulse Nd:YAG ring laser is the most evident in the case of transition from the active to the passive Q-switching.

A Q-switched Nd : YAG laser with a high-power transverse diode pumping and injection of seed radiation generated by a single-frequency semiconductor laser is described. The threshold seed radiation power at which the Q-switched Nd : YAG switches to the single-frequency mode is 0.44 mW (radiation intensity 5.6 x 10(-2) W cm(-2)). With increasing injection power, the spectral and power characteristics of the Q-switched laser almost do not change at a constant excitation of its active medium. The spectral linewidth of the Q-switched Nd : YAG laser with injection from a TLD-1060-14BF single-frequency semiconductor laser module does not exceed 90 MHz (wavelength 1064 nm).

The features of forming output radiation in a powerful monopulse single-frequency side diode-pumped laser operating in external narrow-band signal seeding mode were investigated. The monopulse single-frequency laser was fabricated of a YAG:Nd active element excited by three laser diode matrices. A compact continuous-wave YAG:Nd-laser with longitudinal diode pumping served as the seeding laser. It was shown experimentally that the transition of the monopulse laser from multimode to single-frequency lasing with a spectral line width of about 54 MHz (0.2 pm) occurs at seeding-laser radiation power P th ≈ 0.14 mW (radiation intensity of 1.8·10 –2 W/cm 2 ). Increasing the seeding-laser power over P th does not lead to a noticeable change of the output characteristics of the monopulse laser for a given pump level (above the threshold). If the pump power varies from 1.5 to 3.0 kW, the P th value is not changed but the energy of the output pulses of single-frequency monopulse generation increases to 40 MJ. The low level of the external narrow-band seeding signal allows us to consider the single-frequency low-power semiconductor laser as a promising source of the seeding signal.

The work is devoted to the development and creation of the powerful all solid-state air-cooled multiwave Nd:YAG laser integrated with the output telescope system and to the development of the LD-pumped solid-state source with the extremely narrow lasing linewidth. The laser sources are meant for operation with the multiwave aerosol LIDAR (atmosphere probing altitude is up to 40 km).

An all-solid-state multiwave laser radiator (lasing wavelengths 1064, 532, and 355 nm), integrated in a single implement with a telescope, has been developed for use in aerosol lidars. The main radiator is the master laser and an amplifier based on a YAG:Nd crystal, excited by laser diode arrays using a transverse pumping layout. In the Q-switched regime, the energy of the output pulses of the YAG:Nd laser radiator reaches 400 mJ (1064 nm). With simultaneous lasing at three wavelengths, the radiator forms radiation pulses at 1064, 532, and 355 nm, with energies of 170, 150, and 80 mJ, respectively. The pulse width is 8-11 ns at a repetition rate of 10 Hz. The developed multiwave laser radiator is effective for use as a component of aerosol lidars with an atmospheric probing range of up to 40 km. (C) 2014 Optical Society of America.

The power and output beam spatial properties of the transversally diode-pumped Q-switched Nd:YAG laser with the active element surrounded by the low-absorption light-scattering layer have been investigated. The layer consisted of the bonding agent in which the solid particles, like aluminum oxide or magnesium oxide, effectively scattering the light was uniformly distributed. The particle diameter was mainly in the range of 2–5μm. It has been shown that application of such layer to the diode-pumped Q-switched Nd:YAG laser head allows suppressing the amplified spontaneous emission and/or internally circulating parasitic lasing modes. At the optimized concentration of the light-scattering solid particles the output lasing pulses with the energy of 188–210mJ (the wavelength of 1064nm, the pulse repetition rate of 30Hz) and improved spatial characteristics were obtained using the pump unit based on three laser diode matrixes.

The influence of dispersion in the active medium and selected resonator elements (Fabry–Perot interferometers) on the output characteristics of a two-frequency diode-pumped Nd:YAG laser has been investigated. It is shown that the presence of the interferometers causes the beat frequency to depend on the generation wavelength. Based on this effect, a method to determine small displacements is proposed. A displacement of the resonator mirror as small as ~40 nm (less than one twentieth of the laser radiation wavelength) has been recorded experimentally.

New methods for precise control of main parameters of LD-pumped solid-state lasers assigned for spectroscopic applications have been developed. Tunable lasing in wide range has been achieved. Active elements on the base of crystals (Nd3+:YAG, Nd3+:YVO4) and glasses (Er,Yb doped boro-silico-phosphate glass) were used. The active crystals with uniform and non-uniform distribution of the activator ions were studied. Output beams with high quality and polarization degree have been realized.

This work is devoted to analysis of possibility of control of frequency, polarization and spatial radiation attributes of diode-pumped solid-state lasers (DPSSLs) fabricated on the base of modern active elements (AEs). Crystals of yttrium aluminum garnet and yttrium vanadate activated by neodymium ions (Nd:YAG и Nd:YVO4) lasing at the wavelength λ = 1.06 μm and the boro-silicophosphate glass co-activated by erbium and ytterbium ions lasing in the 1.5 μm spectral region are considered. The schemes of longitudinal and transversal laser diode (or laser diode array) pump are compared. Compact diode-pumped solid-state lasers (DPSSLs) are perspective sources of coherent light for range finding, metrology, spectral analysis as well as for investigations of impact of the radiation on a substance. The predetermined parameters of laser beam are needed for many of these applications. Because of specific properties of DPSSLs (small dimensions, peculiar pump unit and so on) the well known approaches for control of the laser beam characteristics are not always convenient for utilization in practice. As a result, the task of elaboration of the new methods of the DPSSL control and adaptation of the earlier one is posed.

We describe experiments and the corresponding theory of a helium-neon laser containing an optical absorber cell with pure neon, a Faraday rotator and a partial polarizer. The absorber can be modulated. Additionally, a longitudinal magnetic field H induces rotation of the polarization plane of light in the absorber. Modulated output power of the laser is observed. We find good qualitative agreement of the measured data with the theoretical expectation. Under certain conditions the laser system demonstrates unusual behaviour: the output modulation vanishes for a specific choice of H, i.e. the laser becomes insensitive to the presence of the intracavity absorber. The possible spectroscopic application of this effect is briefly discussed.

We propose an intracavity method of determining the spectral linewidth based on the use of a special mode of operation of a laser with a magnetized atomic absorbing medium in an anisotropic cavity when the output radiation power of the laser does not depend on the optical density of the absorbing medium.