Highly transparent terbium gallium garnet crystal fabricated by the floating zone method for visible-infrared optical isolators

Highly transparent terbium gallium garnet (Tb3Ga5O12; TGG) single crystal having a large Verdet constant based on the visible and near-infrared region (VIS-NIR) Faraday rotator was grown by Floating Zone (FZ) growth machine. We successfully grew TGG single-crystal rods of 8-10 mm in diameter, which was suitable for the use in optical devices. The crystal showed a full-width at half-maximum as little as 18 arcsec by the X-ray rocking curve measurement. The Faraday rotation (B = 0.55T) was investigated at wavelength of 532, 632.8, 1064 nm at room temperature. The lower weak absorption coefficient, higher Verdet constant, thermal conductivity and laser induced damage threshold (LIDT) compared to the commercial TGG gives the great potential of using this new method to meet the increasing demand of VIS-NIR Faraday rotators (FRs).