Abstract

Recent development of an all-optical Si switch¹ has led us to investigate a wide variety of nonlinear phenomena in this material. We have previously described our studies of the nonlinear transmission and reflection, the melting threshold, and the surface regrowth morphologies. Here, we quantify the nonlinear refraction induced in Si by the absorption of intense picosecond pulses at 1.06 μm. The temporally and spatially Gaussian profiles of the incident pulses produce a temporally and spatially dependent nonlinear refraction. Consequently, self-phase modulation and self-defocusing are evident in the transmitted pulse. The former effect manifests itself in spectral broadening and a line-center shift, while the latter provides a characteristic near-field beam deformation. A careful analysis of these phenomena has allowed us to determine the effective nonlinear refractive index associated with carrier generation in this material.

© 1985 Optical Society of America