Free-Carrier Optical Nonlinearity Due to Carrier Scattering and Nonparabolicity

Nonlinear mixing of electromagnetic waves in low-temperature degenerate semiconductors has been analytically investigated. Usual kinetic-theory techniques have been employed for evaluating the mixed-frequency components in the current density. Two types of free-carrier nonlinearity are considered, one arising from carrier scattering processes and the other due to nonparabolicity of conduction band. Numerical results, comparing the two nonlinearities for the special case of mixing of two C${\mathrm{O}}_2$ laser beams in indium antimonide, have been presented at the end.