Enhancement of the acoustic phase conjugate reflectivity in nonlinear piezoelectric ceramics by applying static electric or static stress fields

A method to enhance the reflectivity of acoustic phase conjugate mirrors by nonlinear piezoelectricity is discussed. Static electric or static stress fields were applied together with the pump electric field. In highly nonlinear piezoelectric ceramics, the phase conjugate reflectivity was enhanced by the factor of 50 using this method. The maximum reflectivity reached 10−2.