Features of radiation mode structure of a controlled laser unstable two-mirror resonator with deformable mirror

Abstract

The main characteristics (power loss and selectivity, resonance radiation divergence) of a two-mirror unstable resonator with a variable geometric configuration are investigated in the diffraction approximation based on the Fox-Lee equations. A cavity of an unstable confocal geometric configuration was adopted as a basic. At that, the control of the configuration of the resonator and resonance radiation is realized by deforming one of the mirrors (either a concave reflector or a convex counter-reflector). In this work, a comparative analysis of the active resonators characteristics with a deformable reflector and a deformable counter-reflector with the same functions of deformation is carried out. It is shown that, depending on the resonator specific technical parameters and the required power losses, the required concave reflector deformations amplitude in some cases is up to ~ 10% less than in the case of counter-reflector deformations. The mode selectivity of the considered active resonators is practically the same. The considered algorithms for controlling the shape of deformable mirrors make it possible to vary the resonator power losses and control the output laser radiation power over a wide range while maintaining the optical quality of radiation close to diffraction. The results of this work can be used to optimize the scheme and parameters of a laser with a controlled output radiation power.