Thermo-optic characterization of Yb:CaGdAlO4 laser crystal

Principal thermo-optic coefficients (TOCs), dn(o)/dT and dn(e)/dT, are measured for Yb:CaGdAlO4 crystal, for the first time, to our knowledge. At the wavelength of similar to 1 mu m, they equal -7.6 and -8.6 (x 10(-6) K-1), accordingly. Thermal coefficients of the optical path TCOP) are determined for this crystal for the principal crystal cuts (a-cut and c-cut) and light polarizations (pi or sigma). Thermo-optic dispersion formulas are evaluated for both TOC and TCOP coefficients. Optical power of thermal lens is measured for diode-pumped a-cut Yb:CaGdAlO4; it is also calculated on the basis of measured material parameters. Thermal conductivity of CaGdAlO4 crystal is measured versus Yb concentration. The results indicate that a-cut Yb:CaGdAlO4 can provide really athermal behavior. (C)2014 Optical Society of America