Temperature Dependence of the Principal and Additional Refractive Indices of Yb:KGW and KYW Crystals in the Range of 20-400 deg C

摘要

The temperature dependence of the principal refractive indices of potassium-gadolinium tungstate crystals with 7percent Yb impurity and pure potassium-yttrium tungstate without impurities has been measured for seven wavelengths in the visible spectral range at temperatures of 20-400 deg C. It is shown that the thermooptical coefficients for each crystal have different signs at a fixed wavelength. Based on measurements of the temperature behavior of the principal and additional refractive indices and analysis of their thermooptical coefficients, some athermal directions are found in both crystals.