The advantages of applications of diode-pumped solid-state laser based on thulium-doped potassium yttrium tungstate
and Raman laser with the wavelengths of &lgr;~2 &mgr;m and &lgr;~1.6 &mgr;m correspondingly for local coagulation of surface tissue
defects are considered.
Laser operation of passively Q-switched Nd3+:LSB microchip laser with Cr4+:YAG saturable absorber has been investigated theoretically and experimentally. Energy and temporal characteristics of sub-nanosecond output laser pulses have been studied using different combinations of output couplers and absorbers. Generalized model of Q-switched microchip laser has been proposed which takes into consideration thermalization and recombination in laser medium, spatial inhomogeneity of pump and laser intensity, and saturable absorber recovering. Good agreement between theory and experiment has been obtained for wide range of the pump power. Thermalization times of Nd3+ ions in LSB crystal has been estimated to our best knowledge for the first time.
The results of further detailed investigations of passive Q-switch Raman microchip lasers based on Nd:LSB crystal with Ba(NO3)2, BaWO4 and KGd(WO4)2 crystals as intracavity Raman media are presented. It is shown that intracavity stimulated Raman scattering (SRS) in microchip lasers is very simple and efficient method for generation of high power pulses with duration comparable to ones reaching under more technically complicated mode-locking regime. Modeling output energy parameters and emission kinetics of Nd:LSB microchip laser with intracavity SRS on the base of enhanced theoretical model of Q-switch Raman microchip lasers operation taking into account cross-section intensity distribution of pump, laser and Stokes modes, thermalization processes of activator ions on upper and lower multiplet levels and features of saturable absorber intracavity bleaching at spatially nonhomogeneous laser mode has shown good agreement with experimental results.
Lanthanum beryllate, new efficient solid-state laser material for laser diode pumping has been investigated. Slope efficiency comparison for BEL:Nd and YAG:Nd under the same cavity conditions was carried out. Two wavelength lasing regime for fundamental mode and tunable four wavelength lasing regime for intracavity doubled mode were observed.
Disordered crystal with Ca-gallogermanate structure are one of the most appropriate laser materials for compact systems with different special lasing regimes. Output power dependence on laser diode pump power and pumping wavelength temperature tuning of Nd:La3Ga5.5Nb0.5O14 laser, one of a large group of Ca-gallogermanates, under laser diode pump are presented in this research. Maximum output power of 68 mW under 250 mW pump power was reached. Slope efficiency was 41 percent.
Influence of light feedback in laser diode end-pumped Nd3+:KGd(WO4) laser with intracavity doubling as well as wavelength temperature variations of the pump source on stability of solid-state laser output power and efficiency have been investigated. Threshold and slope efficiency were measured under different output coupler transparencies and pumping beam waist sizes. Maximum output power of 130 mW for fundamental mode and 25 mW for SHG was obtained.
Holographic interferometric technique for measurement of laser diode crystal thermoelastic deformations is presented. Using this technique allows us to estimate thermoelastic stresses in laser crystal, active layer temperature and dynamics of heat transfer from laser crystal to heatsink.
Interferometric measurements of wavefront phase distributions for laser diodes applied in optical disk memory units were carried out. The influence of laser diode wavefront astigmatism on the focused light spot dimensions was investigated.