Abstract

Most of the technical challenges encountered in scaling flashlamp-pumped solid-state lasers to high-average-output power arise from the thermal load. Cooling the surface of the solid-state laser medium generates internal temperature gradients which lead to wave front distortions, depolarization, and, if pumping or cooling is nonuniform, beam steering. A variety of solutions to these problems have been proposed, and several are presently undergoing vigorous development. An approach offering great potential involves optical phase conjugation. The initial report¹ of phase conjugation via stimulated Brillouin scattering (SBS) showed that aberrations in a laser beam could be eliminated by reflecting the beam off a SBS cell and passing the beam back through the source of the aberrations. This double-pass phase-conjugate configuration was quickly used to demonstrate² compensation for phase distortions in an active ruby amplifier, thereby indicating an approach whereby nearly diffraction-limited performance could be achieved with a laser oscillator/amplifier configuration: phase conjugation successfully maintains the high-oscillator beam quality, while the pulse energy is increased by two passes through the amplifier.

© 1986 Optical Society of America