Temperature dependence of the far-infrared ordinary-ray optical constants of sapphire

The refractive index n(ν) and absorption coefficient α(ν) of c-cut sapphire are measured at the temperatures 5.5, 30, 60,150, 200, 250, and 300 K for frequencies between 30 and 230 cm−1. Values given for n are accurate to within 1% and those for α to within 5%. Polynomial fits are included, and evidence of multiphonon absorption is also shown.