Abstract

Glasses doped with semiconductor microcrystals (such as CdS_xSe_1–x) are available commercially as inexpensive steep long-pass colour filters having bandgap energies which span the UV to near-IR spectral region. The discovery by Jain and Lind [1] that these materials exhibit large bandgap-resonant nonlinearity has aroused considerable interest in their possible application for all-optical signal processing. This interest was increased by the observation by Yao et al [2] of fast response times for the optical nonlinearity measured by degenerate four-wave mixing (DFWM); a fast nonlinearity, not resolved by the 30 ps laser pulse-width, was observed superimposed on a strong slow background contribution which was interpreted as being thermal in origin. However, in similar studies by Roussignol et al [3] such a fast nonlinearity was not observed.

© 1986 Optical Society of America