Dispersion and temperature dependence of the refractive indices of pure and Yb^3+-doped crystals of YAl_3(BO_3)_4

Abstract

The dispersion of the refractive indices of nominally pure crystals of yttrium orthoborate and of yttrium orthoborate crystals doped with 7at.%Yb3+ has been measured in the visible region. The introduction of 7at.%Yb3+ produces an appreciable increase (in the third place after the decimal) of the refractive indices of the crystal and increases its anisotropy. The temperature dependences of the principal refractive indices have been measured in the range 293–633K, and the first- and second-order temperature coefficients have been found. The refractive index of the extraordinary ray increases with temperature more rapidly by a factor of 1.5–3 (depending on the wavelength) than the refractive index of the ordinary ray.