Aspects of thermally induced nonlinearities in the index of refraction are investigated for the case of degenerate four-wave mixing (DFWM). An expression for the reflectivity is derived within the framework of a coupled thermodynamic–electromagnetic theory, and some implications for the conjugation efficiency are briefly discussed. We also report on experimental measurements of phase-conjugate reflectivities in excess of 200% at 532 nm and comment on the role of saturation effects and pump delays in obtaining the observed efficiencies. Finally, the results of near-field conjugation beam-quality studies are presented with a view toward examining some of the parameters crucial to conjugation fidelity in typical DFWM experimental setups.
© 1983 Optical Society of America
M. H. Garrett and H. J. Hoffman, "Thermally induced phase-conjugation efficiency and beamquality studies," J. Opt. Soc. Am. 73, 617-623 (1983)