Numerical simulations of thermal focusing and thermally induced birefringence effects in diode side-pumped Nd:YAG lasers

The technology of diode pumping has made possible the development of a new generation of efficient solid-state lasers. Simulation models are very useful for improving the understanding of the behaviour of such lasers, for evaluation of laser configurations, and for system optimisation.1-4 We have developed a simulation code for diode-pumped Q-switched Nd: YAG oscillators and amplifiers with both "straight-through" and zigzag slab crystal geometries.4 The model calculates the spatial and temporal evolutions of the populations in the upper and lower laser levels due to pumping, relaxations, and stimulated emission, and of the laser field due to gain, loss, and diffraction. In Ref. 4 we presented results of simulations for a 1 J/pulse system with a rod-based oscillator and a zigzag slab amplifier. We will present results for rod-based oscillators, with emphasis on effect caused by thermally induced focusing and birefringence.