Transparency and mode selectivity of variable-configuration resonators for control of laser radiation power

Algorithms are given for control of the geometric configuration of optical resonators by deformation of reflecting surfaces of two or one of the mirrors in an unstable resonator. Investigations of the characteristics of variable-configuration resonators are made using the quasigeometric approximation, perturbation theory, and numerical methods. It is shown that the proposed algorithms make it possible to control the resonator transparency at the frequency of the fundamental mode and ensure a mode selectivity of the resonator transparency which is not inferior to that in an unstable resonator. The optical quality of the radiation obtained using variable-configuration resonators is close to that typical of unstable resonators with spherical mirrors. The use of variable-configuration resonators (in place of spherical-mirror unstable resonators) makes it possible to control the laser radiation power and to increase the power density in the far-field zone; this increase ranges from tens of percent to severalfold enhancement.