Dynamics of self-interaction of neodymium laser radiation in II–VI semiconductors

It is shown that a positive change in the refractive index n, in the field of a light wave, in II–VI semiconductors follows the variation in light intensity in a single laser pulse with practically no time lag, but the relaxation of the negative nonlinear contribution to n correlates with the lifetime of the nonequilibrium free carriers which result from two-photon absorption. It is also shown that the principal mechanism of nonlinearity in n which leads to self-focusing is the nonlinear polarizability of the bound electrons, whereas the nonequilibrium free carriers determine the nature of the nonlinearity which results in self-defocusing of the laser beam.