A QUANTITATIVE STUDY OF THE PIEZOOPTICAL ACTIVITY IN GAAS

The optical activity induced by uniaxial stress in GaAs is shown to be an order of magnitude smaller than previously reported. The former ov erestimation is explained by birefringence effects related to tiny mis alignments in the stress, which we properly separated from the true op tical activity using phase-sensitive transmission experiments. The new experimental results are compared to a simple critical point analysis and to full band structure empirical pseudopotential calculations. We find good agreement for the sign, the absolute value and the trends i n the dispersion of the optical activity. Attention is paid to the rol e of the interband deformation potentials which determine the sign of the gyrotropic effects. A sign conflict, present in former calculation s, is solved.