The effect of illumination on the characteristics of acoustic waves in a piezoelectric plate-photoconducting layer structure

Abstract

The effect of light on the characteristics of an acoustic wave with the transverse-horizontal polarization (SH0) propagating in a piezoelectric plate-photoconducting layer structure was theoretically studied. Applied to the case of an Y-X cut lithium niobate (or Y-X potassium niobate) plate coated by a cadmium sulfide layer with the thicknesses h1 and h2, respectively, the results of this analysis show that the photosensitivity of such structures strongly depends on the h1 and h2 values, reaching a maximum for h1=0.1λ and h2=0.01λ (where λ is the acoustic wavelength). In the lithium niobate based structure with these parameters, the maximum value of the relative change in the wave velocity in response to the illumination intensity variation from 0.1 to 106 lx is 16% at a maximum damping rate of 5 dB/λ; the analogous values for potassium niobate are 47% and 17 dB/λ. These results show good prospects for the use of such a piezoelectric plate-photoconducting layer structures in photodetectors and optical radiation sensors.