Abstract

Previously reported studies of nonlinear refraction in InSb revealed values equivalent fo an effective degenerate χ⁽⁹⁾(ω:ω₁−ω,ω)~1 esu at 77K.¹ This nonlinearity produced observations of optical bistability at 5 and 77 K (Ref. 2) and DFWM at 5 K (Ref. 3) of cw CO radiation just below the optical band gap energy. Greatly enhanced reflection efficiencies (above the 1 % observed at 5 K) were to be expected using the larger value of the nonlinearity at 77 K. The experimental arrangement for measuring the DFWM efficiency of cw CO radiation in InSb at 77 K is shown schematically In Fig. 1. This setup produces a front pump beam and a probe beam (at an angle of ~1° to the front pump beam) both gently focused to a spot diameter of ~1.3 mm at the sample. The counterpropagating back pump beam is generated by a single reflection of the front pump beam from the polished natural reflectivity (R ~36%) back face of the sample.

© 1983 Optical Society of America