Theory of Intensity Dependence of Refractive Index

The variation of refractive index with intensity of irradiation is explained on the basis of a three stage process, viz. (i) photogeneration of free carriers, (ii) shift of the absorption edge by a dynamic Burstein‐Moss effect, and (iii) reduction in total absorption and hence of refractive index as a result of the inter‐relation of the optical constants. The theory gives the correct sign, magnitude, and wavelength dependence of the effect.