Thermooptic Coefficients of Nd-Doped Anisotropic KGd(WO4)2 Laser Crystals.

Abstract

Thermooptic coefficients dn/dT of anisotropic crystals Nd(3 at.%):KGd(WO4)2 and KGd(WO4)2 were measured by means of beam deflection method at 632.8 nm, 300 K. It was found that thermooptic coefficients in KGd(WO4)2 depends only on the light polarization but not on the light propagation direction and do not change significantly with crystal doping up to 3 at.%. The dn/dT values for light polarized along the optical indicatrix axes Nm, Np and Ng are negative in Nd:KGd(WO4)2 and equal dnp/dT = -14.8 x 10-6 K-1, dnm/dT = -10.1 x 10-6 K-1 and dng/dT = -16.0 x 10-6 K-1. Athermal propagation directions were found in Nd:KGd(WO4)2 for light polarized along the Np and Nm optical indicatrix axes (with dn/dT+(n-1) = 0 definition) and for light polarized along the Ng and Nm axes (with dn/dT+n = 0 definition).