Abstract

In the past few years, glasses doped with micro-crystallites of semiconductor material have been proposed as candidates for the fabrication of nonlinear optical switching and modulation devices because of their reasonably strong nonlinear response, subnanosecond response time, and ease of waveguide fabrication. We investigated these glasses using nonlinear transmission measurements and degenerate four-wave mixing. We have done these measurements on a time scale that is longer than the relaxation time (~100 ps-1 ns), of the order of the relaxation time, and shorter than the relaxation time (15-ns, 80-ps, and 30-ps laser pulses, respectively). We have also demonstrated four-wave mixing in a single-mode planar waveguide,¹ an important first step toward nonlinear waveguide devices. We compared the experimental results to a theoretical model. The model uses the powerful plasma theory of Banyai and Koch² to model the semiconductor response. The comparison indicates that a carrier-dependent relaxation time is necessary to explain the data. Whether this is a radiative-type recombination or an Auger-type process is unclear. We also explore the effect of two-photon absorption on the model.

© 1988 Optical Society of America