The General Condition for Intensitivity Against Thermal Lensing of Multielement Resonators

Abstract

Optical pumping induces thermal lensing in a laser rod, which degrades the beam quality and reduces the output stability of the solid-state laser and should be minimized for practical applications. One method to solve this problem is the design of dynamic stable TEMoo-mode resonators proposed first by Steffen et al [1]. In order to increase TEMoo-mode volume, increase effective resonator length or reduce beam devergence, multielement resonators are often used. In this paper, using the equivalent resonators and transfer matrix method and following the calculated results in [2],[3], the condition for insensitivity against thermal lensing of multielement resonators is derived analytically for the first time. The expression is simple but exact and holds for the general case, a typical and important example is telescopic resonator.