Abstract

Monoclinic double tungstates (DTs) with a chemical formula KRE(WO₄)₂ or simply KREW where RE stands for Gd, Y or Lu, and doped with rare-earth ions like Yb³⁺, Tm³⁺ or Ho³⁺ are the well-known materials for high-efficient lasers emitting at ~1 and ~2 μm [1]. Recently, a lot of attention was paid to the choice of best orientation of crystal cuts from DTs (typically, referred to the dielectric frame axes) with an improved thermo-optic behavior. DTs are optically biaxial and they exhibit the conical refraction (CR) effect. The latter is used in the CR lasers with their cavity aligned along one of the two optical axes of DTs. In the present paper, we report on the direct measurement of rotation of the dielectric frame for three main representatives of DT family, and the consequences on the position of the optical axes and on the CR angle.

© 2015 IEEE