TE-TM Mode conversion optical isolator fabricated by wafer bonding

A TE-TM mode conversion optical isolator with a semiconductor guiding layer was studied. The optical isolator was comprised of a magneto-optic waveguide with a magnetic garnet / GalnAsP / InP structure, which was fabricated by wafer bonding technique. The optical isolator was designed at a wavelength of 1.55 μm for satisfying a phase matching condition between a TE mode and a TM mode. An optical confinement factor in the magnetic garnet layer was calculated to obtain the propagation distance required for the π/4 rad mode conversion. The length of the nonreciprocal mode converter was estimated to be approximately 7.9 mm with a 0.55-μm-high GaInAsP strip-loaded waveguide. Wafer bonding was investigated between the GaInAsP strip-loaded waveguide and a magnetic garnet to construct the optical isolator.