Refractive index dependence on free carriers for GaAs

Abstract

This work reports on the influence of the injected free carriers on GaAs refractive index N at 297 °K. The variation of N caused by injected free carriers was theoretically calculated in a more complete way than has been performed earlier. New results were obtained rather than those of a reducing effect on N in a linearlike dependence on the injected free carrier concentration n. They are: (1) linearlike dependence of N on n occurs only beyond a certain value n₁ and (2) an increasing effect on N is caused by the injected free carriers for concentrations in the range between n=0 and a certain value of n=n_c (n_c<n₁) . In the range n_c<n<n₁ a nonlinear decreasing effect was obtained. Effect (2) has not been noticed up to now, so far as the authors know.