Self-regenerative laser oscillator-amplifier

Abstract

Apparatus is provided which includes a laser oscillator for providing light along a first optical path, and a laser amplifier for amplifying light along a second optical path. Means for coupling light between the first and second optical paths is disposed at one end of the laser amplifier, and a nonlinear medium disposed at the other end thereof for intercepting light provided along the first and second optical paths. The laser oscillator provides a single-mode laser beam along the first optical path which is made incident upon the nonlinear medium from substantially opposite directions. A portion of the beam from the laser oscillator is coupled through the laser amplifier, which forms a probe beam that samples the laser amplifier system. This beam further impinges upon the nonlinear medium and interacts with the counter-propagating laser beams therein. A phase-conjugated beam is reflected from the nonlinear medium and is amplified by the amplifying medium providing a single-mode output beam of the laser amplifier system. A portion of the phase conjugated beam is reflected back into the oscillator and used as the counter-propagating pump beams for the phase conjugation process. This self-pumping feature allows for minimization of the pumping power required for the oscillator. The combination provides for a phase corrected, diffraction-limited beam at the output of the system. A second embodiment utilizes the amplifier medium to accomplish both amplification and phase conjugation therein.