Semi-classical theory of Q-switched microchip - lasers with transient and quasi-stationary intracavity Raman conversion
has been developed. Rate wave equations describing generation of Stokes pulses of different orders and their multiwave
mixing have been written and discussed in detail. Theoretical results agree well with experiments for passively Q-switched
microchip - lasers with intracavity Raman conversion in crystals of Ba(NO3)2 and CaMoO4. It is shown, that intracavity Raman conversion in microchip - lasers represents a simple and effective method of generation of short
Stokes pulses with duration as short as 100 ps, energy in the &mgr;J-range and peak power of up to several tens of kW.
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.
Investigation and modeling of dynamics and stability of long-wavelength quantum-well lasers with carrier transport effects subject to a phase-conjugate mirror has been developed. Unremovable in quantum-well lasers carrier transport affects significantly both cw and dynamic laser performance. Laser stability, phase locking, and dynamics have been studied by the analysis of the laser rate equations describing optical field and carrier transport including carrier diffusion is separate confinement heterostructures, carrier capture and escape in quantum wells. It has been shown, that in long-wavelength quantum- well lasers carrier transport narrows drastically the laser- stability reign in approximately equals 1.5 to approximately equals 2.5 times and increases the unstable -output oscillation frequency in approximately equals 2 to approximately equals 3 times.
The effect of nonradiative Auger and Shockley-Hall-Read recombinations and nonlinear gain on an InGaAsP/InP (A.=1.3 μm) and AlGaAs/GaAs laser transient process and threshold parameters has been studied on the basis of numerical solving the rate equations of an injection laser. N onradiative recombination increases the delay time of an output switching on and decreases the damping rate of output relaxation oscillations significantly.
Keywords: injection lasers, transient processes, output dynamics, Auger recombination, Shocley-Hall-Read recombination, threshold parameters
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.