Magneto-optical isolator with silicon waveguides fabricated by direct bonding

A magneto-optical isolator is demonstrated for use with a Si waveguide. The isolator is based on a Mach-Zehnder interferometer employing a nonreciprocal phase shift and is fabricated by bonding a magneto-optic garnet CeY2Fe5O12 (Ce:YIG) directly onto the Si waveguide. The surface-activated bonding is based on oxygen-plasma exposure in a high-vacuum chamber. The nonreciprocal phase shift is observed by applying an external magnetic field. An isolation ratio of 21 dB is obtained at a wavelength of 1559 nm. (C) 2008 American Institute of Physics.