Abstract

This paper describes studies of nonlinear refraction in low band gap semiconductors in a variety of sample conditions at room temperature. Time- resolved self-defoeusing of 10.8-μm laser pulses shows complex beam profile dynamics after propagation through thin samples of CdHgTe and InSb. Two-photon absorption coefficients are large in these low gap semiconductors,¹ but it was found that nonlinear refractive effects associated with the generated carriers² dominate the measured on- axis transmission over the absorption due to the two-photon or free carrier processes alone. Self-defocusing due to three-photon excitation is measured for the first time in larger band gap CdHgTe, while an alloy composition with lower gap allowed band gap resonant conditions to be explored.

© 1986 Optical Society of America