Space-charge wave excitation by superposition of static and moving interference patterns

Abstract

The optical excitation of space-charge waves ͑SCW͒ has been realized experimentally by superposition of static and moving light interference patterns with Bi 12 GeO 20 as an example. A clear resonance behavior of the ac detected in an external electric circuit, as well as an inverse dispersion law, is verified, and a low frequency signal due to a modulation of the photoconductivity appears. The results are compared to the classical method using an oscillating light pattern for excitation. The optimized method allows for the detection of the charge carriers participating in SCW formation and yields an excitation of higher quality.