Abstract

It has been noted by others that the spatial beam quality and stability of phase conjugate resonators have been improved by introduction of intracavity apertures. Such apertures are effective at reducing the number of allowed modes for the phase conjugate resonator. Allowing a large number of modes to run adversely affects clean propagation of the beam. Our paper examines the mode structure of the field in a phase conjugate resonator. The phase conjugate resonator was composed of a self-pumped barium titanate crystal and a conventional mirror setup in a self-oscillating configuration. The intracavity mode structure was sampled using a shear plate. We find that the mode structure is dramatically improved by insertion of appropriately sized intracavity apertures. Aberrations placed between the conventional mirror and the intracavity aperture were found to destroy the phase conjugate nature of the counterpropagating fields in that region of the cavity.

© 1987 Optical Society of America