Spectral dependence of the Verdet coefficients of terbium gallium garnet and potassium terbium fluoride

High power laser systems require the use of optical isolators to prevent coupling of reflected light into the pump laser. Terbium Gallium Garnet (TGG) and Potassium Terbium Fluoride (KTF) are materials used as optical isolators and while they have been grown for many years, advances in crystal growth and processing make a new set of measurements of the Verdet coefficients of these materials desirable. We present new measurements of the Verdet coefficients of TGG and KTF from 0.405 μ to 1.55 μ and derive expressions for the spectral behavior of the Verdet coefficients.