Patent ID: 8660391

Claim:
An optical isolator comprising: a first optical grating coupler to receive light from a first waveguide and to direct light having a polarization component substantially normal to a surface of the first optical grating coupler that is parallel to the first waveguide; a non-reciprocal polarization rotator to receive light from the first optical grating coupler at a first surface and to rotate the polarization of the light at a principle direction; a reflecting surface to reflect the rotated light at a second surface of the non-reciprocal polarization rotator; and a second optical grating coupler positioned to receive the rotated light from the non-reciprocal polarization rotator at the first surface and to direct the received light to one of a plurality of output waveguides based on the polarization of the received light, the second optical grating coupler to receive light substantially normal to a surface of the second optical grating coupler that is parallel to the plurality of output waveguides.