The Change of the Refractive Index of Some Germanium Films Irradiated by Intense Light

Abstract

A Rayleigh Löwe Interferometer has been modified to measure the changes of the refractive index of several germanium films when they are irradiated by the intense white light. The refractive index of the films was found to increase when the colour temperature of the irradiating light source was ca. 3000 K and to decrease when the temperature was ca. 1000 K. From the dispersion curves, it was suggested that the present effects were caused by the variation of the number of the bounded electrons and not of the free carriers.