Fabrication processes of a magneto-optic waveguide with a Si guiding layer for an optical isolator employing a nonreciprocal guided-radiation mode conversion are investigated. The optical isolator is constructed on a silicon-on-insulator (SOI) structure. The magneto-optic waveguide is fabricated by bonding the Si guiding layer with a cerium-substituted yttrium iron garnet (Ce:YIG). The relationship of waveguide geometric parameters is determined at a wavelength of 1550 nm. The results show that larger tolerance for isolator operation can be obtained at smaller gaps between Si and Ce:YIG. Bonding processes including photosensitive adhesive bonding and surface activated bonding are then compared. It is found that the surface activated bonding process is easier to control and more promising than the photosensitive adhesive bonding.
Higher order mode conversion via focused ion beam milled Bragg gratings in Silicon-on-Insulator waveguides