Numerical study of unstable resonator in thin disk laser

Abstract

In this paper a disk laser with unstable resonator is investigated numerically. Using Collins integral and diffraction theory, a positive branch confocal unstable resonator with a thin disk shape active medium is simulated. Thermal lensing of the disk is considered in our research. Laser beam profile and output power are calculated for unstable resonator with variable internal lens. The calculations show instability of output laser beam during pump power increasing due to changes of disk dioptric power. Also calculations show that power extraction is only possible for lasers with not too thin disks.