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 mu to 1.55 mu and derive expressions for the spectral behavior of the Verdet coefficients.

Northrop Grumman Synoptics is de­ veloping the growth of large single­ crystal fluoride materials for Faraday rotator / isolator applications. These materials exhibit smaller nonlinear refractive index and thermo­optic coefficients, while maintaining Ver­ det constants near those of the com­ monly used terbium gallium garnet (TGG) crystals. In particular, the cu­ bic potassium terbium fluoride, KTF (KTb3F10) crystal has low absorption and thermo­optic coefficients. The crystal growth and performance of these single­crystal fluoride materi­ als will be discussed as well as recent improvements to the performance of TGG crystals.

Northrop Grumman Synoptics is developing the growth of large singlecrystal fluoride materials for Faraday rotator / isolator applications. These materials exhibit smaller nonlinear refractive index and thermo-optic coefficients, while maintaining Verdet constants near those of the commonly used terbium gallium garnet (TGG) crystals. In particular, the cubic potassium terbium fluoride, KTF (KTb3F10) crystal has low absorption and thermo-optic coefficients. The crystal growth and performance of these single-crystal fluoride materials will be discussed as well as recent improvements to the performance of TGG crystals.