PARAMETRIC AMPLIFICATION AND FREQUENCY SHIFTS IN ACOUSTOELECTRIC EFFECT

Mechanisms for downshift in frequency of maximum acoustic intensity for high flux domains in piezoelectric semiconductors are reviewed; for simple case where externally introduced acoustic wave (pump) produces single-frequency domain in photoconducting CdS, clear evidence is given that xownshift is due to parametric amplification of thermal acoustic noise; downshifting in region where deviations from linear theory are still small is discussed in terms of parametric interaction model.