DFWM reflectivity via two-photon free carrier generation in semiconductors in middle-IR range

It's shown that the effect of two-photon free carrier generation (TFCG) in semiconductors is the most promising for achieving high DFWM reflectivities R with short enough decay time tau in wavelength range from 1.5 to greater than 9.5 micrometers. The materials which allow us to achieve R up to 100% with tau of order of nanoseconds for the range of interest are presented. Some specific features of DFWM via TFCG were studied experimentally in InSb at lambda equals 10.6 micrometers and in Ge at lambda equals 2.94 micrometers.