Crystal Growth of a Highly Bi-Substituted Gadolinium Iron Garnet and Its Application to an Optical Isolator

Abstract

Single crystals of highly Bi-substituted gadolinium iron garnets have been grown by an improved flux method using Bi₂O₃ as a flux. Faraday rotation and optical absorption were measured in the near-infrared region at room temperature. The Faraday rotation of Gd_3-xBi_xFe₅O₁₂ increased linearly with x up to 1.15 and the magneto-optical figure of merit reached 180 deg./dB at 1.0μm in Gd_1.85Bi_1.15Fe₅O₁₂. By using this crystal as a Faraday rotator, a compact optical isolator has been developed for near-infrared light. The optical isolator featured <1 dB insertion loss and 36dB isolation at a wavelength of 1.15μm.