Oscillation modes in resonators with mirrors performing partial wavefront reversal

A matrix approach is used to study the simultaneous influence of the frequency shift, and of amplitude and phase distortions arising in the course of partial wavefront reversal on the behavior of oscillation modes in a resonator with a wavefront-reversing mirror. It is shown that amplitude distortions associated with the finite transverse dimensions of such a mirror generate, in most systems employed in practice, oscillation modes typical of a stable resonator and the role of phase distortions and frequency shift then reduces to mode deformation. It is shown that if phase distortions are introduced into a wavefront-reversing mirror, it is possible to construct a resonator generating highly directional radiation in the form of the lowest transverse mode which is characterized by a large volume and is insensitive to intracavity phase distortions.