Phase Conjugation In Semiconductor Lasers

We demonstrate phase-conjugate reflectivities on the order of 1000 at frequency detunings on the order of 0.5 GHz in intracavity nondegenerate four-wave mixing in a semiconductor laser. Our measurements show that, unlike a third-order nonlinearity, the conjugate reflectivity does not scale like the pump power squared, indicating that saturation and cavity effects are important in the generation of the conjugate.