Time Investigation of Parametric Interactions in Acoustoelectric Oscillators

Abstract

The generation of resonance frequencies is studied in thick shear wave acoustoelectric oscillators where non‐linear single mode or multimode conversion can occur. This generation takes place in a general manner including a down‐jump of acoustoelectric current, the incubation time of which is much longer than the common linear onset‐time, and the suppression of components in the first linearly amplified spectrum. The onset time and threshold field measurements of these processes are reported as a function of the bias field and the conductivity. In the experiments, by the use of obliquely and transversally cut CdS crystal samples, the bias field is oriented on two axis so that the acoustic propagation vectors are in the direction of the two maxima of the electromechanical coupling coefficient K2θ. The experiments are compared to an interferometric model made from Conwell's and Ganguly's theory. In these oscillators the observed irregular behaviour of current is found to be entirely due to the parametric amplification processes.