Calculating optical path difference in end-pumped Yb:YAG thin disk lasers

Abstract

In real thin disk laser systems, a fraction of absorbed pump power is dissipated as heat. Consequently, the thin disk lasers experience a temperature gradient in the axial direction of the disk which produces inhomogeneous stress and strain distributions. In this paper, we present the numerical calculation of Von Mises stress and the thermal lensing due to temperature gradient, stress gradient and deformation. Based on the results of our numerical study, it was proved that the most dominant parameters, which cause optical path difference and therefore thermal lensing, are temperature-dependent refractive index and deformation of the disk. Moreover, these are both directly related to absolute temperature values within the crystal.