Optical Properties of Indium Antimonide in the Region from 20 to 200 Microns

Abstract

The reflectivity and the transmission of InSb crystals ($n$-type) were measured between 20 and 200μ. The reflectivity curve has a sharp maximum at 54.6μ and the transmission curve shows a low transmission at the same wavelength due to lattice vibration of this crystal. The transmission curve shows a weak absorption at 28.3μ due to the overtone of that lattice vibration. The reflectivity curve shows another flat peak at longer wavelengths. The reflectivity minimum between these two peaks shifts from 160 to 72μ with increase of temperature from -35 to 130°C, and the maximum value of the flat peak increases with increase of temperature and is 80% at temperatures of 100°C or more.