Temperature Dependence of the Refractive Index of Optical Maser Crystals

This paper reports the index of refraction of CaWO4, CaF2, and BaF2 for wavelengths from 4350 to 18 460 Å and over the temperature range −180°C to room temperature. Measurements are made on dilute ruby at 5461 Å from −180° to 70°C. The results are applied to an interpretation of the output frequency of solid-state optical masers.