Magneto-optical properties of Tb0.81Ca0.19F2.81 and Tb0.76Sr0.24F2.76 single crystals

High optical quality terbium calcium fluoride (Tb0.81Ca0.19F2.81) and terbium strontium fluoride (Tb0.76Sr0.24F2.76) single crystals have been grown by the Czochralski method under controlled atmosphere. While both compounds present similar optical and magneto-optical properties (determined by the high concentration of Tb3+ ions), the lower absorption losses and high Faraday rotation exhibited by terbium calcium fluoride, compared to those of terbium strontium fluoride, lead to a notable figure of merit for Faraday isolators operating in the visible wavelength region. In particular at short wavelengths, below 500 nm, the figure of merit of terbium calcium fluoride is remarkably higher than that of the industrial standard terbium gallium garnet.

► Tb0.81Ca0.18F2.81 and Tb0.76Sr0.24F2.76 were grown by the Czochralski method.
► Both crystals are highly transparent in the VIS-midIR region.
► Tb0.81Ca0.18F2.81 and Tb0.76Sr0.24F2.76 possess large Verdet constants.
► Tb0.81Ca0.18F2.81 shows high figure of merit for wavelength below 500 nm.