Abstract

The ability of a phase conjugate mirror (PCM) to correct for intracavity phase aberrations, when substituted for a conventional spherical mirror (CM) in an optical resonator, is compromised by the presence of apertures located inside the cavity.¹ We show that aperture effects in the entrance plane of a four-wave mixing cell, as caused by the use of finite-width pump beams, may be greatly reduced through proper design of the laser cavity. The basic concept is the matching of cavity modes to those of the PCM. Only the phases are of primary importance, and the matched modes have focus inside the mixing cell.² We tested two methods of optimized cavity design as based on a simple model: (a) maximization of PCM effective spot diameter, and (b) a wave front matching criterion applied to the CM end of the cavity. Both techniques reduce intracavity phase aberration effects on the output beam by typically 2–3 orders of magnitude compared to predictions based on cavity modes which have the beam waist located in the PCM entrance plane.

© 1985 Optical Society of America