Temperature dependences of terahertz spectra of rutile grown by various methods

The paper presents measurements of the temperature dependence of the refractive index and the absorption coefficient in the THz range for rutile crystals grown by the cold container method. The obtained parameters are compared with the temperature behaviour of lithium niobate crystals, whose matrix allows significant deviations from stoichiometry. The coefficient of the temperature dependence of the refractive index of rutile crystals in the terahertz range is commensurate with that of heavily doped lithium niobate samples and is 3·10^-3 K^-1.