DYNAMIC CONTROL OF THE SPATIAL MODES IN THE EXTERNAL RESONATOR OF A SEMILINEAR PHASE-CONJUGATE MIRROR

We describe a technique that causes the radiation within the external resonator of a self-starting, semilinear phase-conjugate mirror to collapse into a single spatial mode. We have developed a model based on competition between gratings in one interaction volume to explain the observed dynamic behavior. The model shows that, once the system reaches the steady state, two gratings, whose amplitudes vary throughout space in proportion to each other, form. As a result, we can obtain analytic solutions for the steady state by using an interpretation of four-wave mixing in terms of two-wave mixing. This interpretation can be used in both the transmission and the reflection geometries for real or complex coupling with no absorption.