Improved performance from noncollinear pumping in a high-reflectivity Brillouin-enhanced four-wave mixing phase conjugator

A Brillouin-enhanced four-wave mixing conjugator having reflectivities in excess of 10/sup 6/ for probe inputs of less than 1 nJ is described. Improved performance is obtained by using a pumping geometry which minimizes beam distortion and is not precisely counterpropagating. When adjusted for maximum reflectance, output in the far field is exactly retroreflective with respect to the input. The output can be steered away from 180 degrees C without severe losses in performance by adjustment of the pumping geometry. Such behavior is consistent with a model based on the extended beam overlap geometry.<
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