Optical nonreciprocal devices with a silicon guiding layer fabricated by wafer bonding

Optical nonreciprocal devices with a silicon guiding layer fabricated by wafer bonding are proposed. The optical nonreciprocal devices are composed of a magneto-optic waveguide with a magnetic garnet/Si/SiO₂structure. Nonreciprocal characteristics are obtained by an evanescent field penetrating into the upper magnetic garnet cladding layer. Several kinds of the optical nonreciprocal device are investigated with the magneto-optic waveguide and designed at a wavelength of 1.55 μm. As a preliminary experiment, wafer bonding between Gd₃Ga₅O₁₂and Si was studied. Wafer bonding was successfully achieved with heat treatment at 220 °C in H₂ambient.