Refractive indexes and temperature coefficients of germanium and silicon

The refractive indexes and their variations with temperature for silicon and germanium have been measured over the 95-298-K and 2.5-12-microm ranges. Data are given for the refractive index that are in reasonable agreement with those of previous investigators. For dn/dT the values are independent of wavelength and are approximately 1.5 x 10(-4) (K)(-1) and 4.0 x 10(-4) (K)(-1) for silicon and germanium, respectively.