Preparation of Magneto-Optic Single-Mode Buried Channel Waveguides of Lanthanum- and Gallium-Substituted Yttrium Iron Garnet

Magneto-optic single-mode buried channel waveguides are prepared using lanthanum- and gallium-substituted yttrium iron garnet [(La, Ga):YIG] liquid-phase-epitaxial film. The film growth conditions, film properties and the core ridge fabrication method are described. The refractive index of the film is controlled with the film growth temperature. The core ridge size is well controlled using ion beam etching. The obtained waveguides provide low loss coupling with a silica-based waveguide, which is a platform waveguide for a hybrid optical integrated circuit. Magneto-optic mode conversion is observed in a weak applied magnetic field, and the conversion efficiency R max and isolation ratio are evaluated. The relationship between R max and the stress-induced birefringence is discussed.