Index gratings stabilized by deep centres for fast optical addressing

Abstract

We study the subnanosecond optical addressing capabilities of semiconductors based on the diffraction properties of plasma index gratings. This paper reports new results on GaAs :Cr semi-insulating samples. The diffraction efficiency of the refractive index grating remains constant (~ 5 x 10~~) in the nanosecond time scale. The grating erasure is however possible using an uniform picosecond illumination a 80 % decrease of the diffraction efficiency is achieved in our experiments. We show that the best model to explain our experimental results is based on the plasma density modulation stabilized by charged deep centres i,ia the electrostatic icreening effect.