Abstract

The diode-pumped solid-state lasers that we are developing reach output powers of currently up to 620 W. The measurements of the thermally induced optical distortions (aberrated lenses, birefringence, bifocussing) show that the most important issue at these powers is the optimisation of the thermal effects. This requires rigorous modelling to first understand and than optimise the most effective parameters. So far, explicit expressions for thermally induced aberrations including birefringence were only known for the simple case of homogeneously heated rods or for rods with top-hat shaped pumping distributions.^1,2 With these models it is impossible to optimise parameters such as pumping light distribution and active ion distributions. Here we present for the first time a general analytical solution of the stationary heat flux equation, where the only condition is the cylindrical symmetry of the heating distribution, leading to the form where Q(r) is an arbitrary heating distribution, T is the temperature, k the heat conductivity and r the distance from the laser rod axis.

© 2000 IEEE