Abstract

Because of its numerous applications, including wave front conjugation and aberration correction, narrowband spectral filtering, and polarization manipulation, there has been considerable interest in degenerate four-wave mixing (DFWM) of CO₂ laser 10-μm radiation. Various materials,^1-6 including molecular saturable absorbers² and semiconductors,^1,1–6 have been used. In semiconductors, a variety of nonlinear mechanisms have been evoked for the process, resulting in successively larger nonlinearities and In extremely large four-wave returns, In particular, semiconductors whose band gaps (or other resonant transitions⁵) are closely matched to the photon energy have manifested large values of the effective third-order susceptibility via a variety of processes, including enhancement of nonlinear motion, free carrier generation, and absorption saturation.

© 1981 Optical Society of America