Measurement of temperature dependent refractive indices of GaN and 4H-SiC

Temperature- and wavelength-dependent values of the ordinary (n_o) and extra-ordinary refractive index (n_e) of GaN and 4H-SiC were measured over wavelength ranges of 1.9 to 7 μm and 1.9 – 5.5 μm, respectively, and over a temperature range of 79 to 400 K. Temperature-dependent Sellmeier equations for both GaN and SiC were obtained and thermooptic coefficients determined.