Self focusing of laser beams in a degenerate nonparabolic semiconductor: Kinetic approach

Using rigorous kinetic treatment the steady state self-focusing of laser beams in a degenerate nonparabolic semiconductor (e.g. n-InSb) has been investigated beyond the perturbation limit. The nonlinearity arises due to the energy dependence of the electron mass in the conduction band. The energy loss of electron energy is assumed to be due to polar optical phonons and momentum transfer due to ionised impurity scattering/polar optical phonon scattering. It is found that nonlinearity in the dielectric constant or the self-focusing is more pronounced in the case of ionised impurity case as compared to polar optical phonon case. The effect of absorption is to suppress the self-focusing but the latter is also enhanced by degeneracy.