High-gain nondegenerate two-wave mixing in Cr:YAlO 3

A gain of 22 times was obtained by nondegenerate two-wave mixing in Cr:YAlO3 To our knowledge, this is the largest cw two-wave mixing gain obtained in a bulk solid-state nonphotorefractive material. The measured gain appears to be limited by beam breakup that is due to spatial nonuniformities in the nonlinear refractive-index change that are the result of inhomogeneities in the crystal. Predictions based on our data indicate that gain in excess of 200 times should be possible in Cr:YAlO3 if a homogeneous crystal can be obtained.