Analysis of Thermal Effects of Rod Laser under Gaussian and Super Gaussian Pumping

In this paper, thermal effects of Gaussian and super Gaussian pumping on the rod laser are analytically investigated. The crystal is considered as a rod, with isotropic thermomechanical characterizations, which is end-pumped. The intensity distribution of pumping spot is considered in three-types including Gaussian, second order and third order of super-Gaussian, and effects of any type on the thermal distribution and thermal lensing are compared with each other. First, the heat generations due to emission in the crystal are calculated for Gaussian and super Gaussian pumping and then the equation of temperature distribution is analytically solved and a closed form solution for temperature distribution of the rod laser is obtained. The analytical results are compared with the results of finite element method. Thereupon, the temperature distributions and the values of thermal lens for various pumping powers are calculated. The results show that calculated maximum temperature for Gaussian case is lower than for supper-Gaussian cases. In addition, the distances between focal point and the input pumping plane obtained for super-Gaussian pumping are larger than those calculated for Gaussian pumping.