Correction of phase distortion by nonlinear optical techniques

This is the final report on a program designed to explore a recently recognized property of certain nonlinear optical interactions of generating conjugate wavefronts that can be used to correct optical distortions in laser systems. These distortions include optical train aberrations, laser medium distortions, and atmospheric propagation aberrations. The program was divided into three basic areas that bridge the gap between a preliminary exploration of the applicable nonlinear processes and realization of their potential usefulness to laser systems. The areas were to measure quantitatively the properties of phase conjugation by four-wave mixing and SBS, to develop a theoretical understanding of nonlinear phase conjugation, and to determine the applicability of nonlinear phase conjugation to various systems of interest to DARPA. Experimentally Demonstrated: Four-wave reflectivity exceeding unity in the green; Complete aberration correction by four-wave mixing and SBS for severely aberrated beams (approx. 35X diffraction limit), Viable approaches to angle offset using four-wave mixing; and Input/output separation using polarization properties of four-wave mixing.