Higher-order piezoelectricity in PZT ceramics and efficiency of acoustic phase conjugation

The principle and basic experimental for generating acoustic phase conjugate waves by conjugate waves at a frequency ω are generated as a result of the interaction between the incident acoustic wave at ω and the pump electric field at 2ω. This process is explained by the modulation of sound velocity by the electric field together with the concept of time grating. Experimental results of the sound velocity modulation and the phase conjugate generation in nonlinear piezoelectric PZT ceramics are shown. The amplitude reflectivity of the phase conjugation was 23% for the acoustic incidence at 10 MHz