Abstract

Direct experimental demonstration of a large refractive index nonlinearity enhanced by surface effect in a doped semiconductor was made recently under conditions of nanosecond laser pulse excitation¹. Measurements of self-diffraction due to photoinduced dynamic gratings were made at room temperature for two n-GaAs:Te samples, with thicknesses of 40 μm and 350 μm and with impurity densities of 2.10¹⁸ cm^-3 and 5.10¹⁸ cm^-3 respectively, using the well known method of self diffraction of light beams due to photoinduced dynamic gratings. The self diffraction efficiency was nearly independent of sample thickness and careful investigation has shown that the diffraction arose primarily at the surface and is resonant just below the band edge.

© 1990 Optical Society of America