Integrated optical isolators with sputter-deposited thin-film magnets

This letter describes the use of a compact sputter-deposited thin-film magnet that is directly integrated onto a waveguide isolator fabricated in magnetic thin-film garnets. Film magnets of different thicknesses are sputtered onto the waveguides, and isolation ratios of 29 dB are obtained with negligible excess loss. Stress-birefringent effects due to the ferromagnetic film overlayer are eliminated by the use of an aluminum compliant buffer.