Nonlinear Effects on LiNbO3 Delay Line Coated with a Polycrystalline CdSe Film

The resistance of a polycrystalline photoconductive CdSe film upon a piezoelectric acoustic surface wave delay line is investigated. During the acoustic pulse propagates in the line, a resistance decrease by a factor up to ten is revealed. The relationship between the resistance change and the acoustic input voltage is strongly nonlinear and this property can be used for nonlinear signal processing. The effect is explained by the intercrystalline barrier modulation by the high electric fields associated with the acoustic surface wave on a piezoelectric substrate. Since the resistance change depends on light intensity, the method can be used, in a limited scale, for acoustical scanning of optical images.