Nonlinear amplification of sound in a piezoelectric semiconductor

Abstract

The results of the nonlinear analysis of acoustoelectric effects previously derived in connection with the acoustoelectric domain are applied here to the time independent amplification of ultrasonic waves of finite amplitude, and the correction to the linear theory which arises out of the acoustoelectric current is derived. The coupled space charge mode plays a critical part in maintaining electrical neutrality and in determining the correction to the growth constant is enhanced for omega > omega _om, unaffected for omega = omega _om and decreased for omega < omega _om, and a downward frequency shift occurs for all frequencies ( omega _om=frequency for maximum gain). The frequency shift is an order of magnitude weaker than change in growth constant.