Dispersion of the Piezobirefringence of GaAs

Abstract
The piezobirefringence of GaAs shows a large anomalous dispersion near the absorption edge and exhibits a nonlinear stress dependence. The coefficient π11–π12 reverses sign. Lowering the temperature from 298° to 77°K shifts the dispersion curves +0.088 eV, which is approximately equal to the shift of the energy gap with temperature. These effects, which have not been observed previously in GaAs, are related to the stress dependence of transitions associated with the absorption edge and resonance photoelasticity described by Kaplyanskii and Lozovskaya.