Patent ID: 6853487

Claim:
An optical device, comprising: a first polarization beam splitter (PBS); a first set of optical rotators optically coupled to the first PBS at a face intersecting a first axis of the device, the first set of optical rotators comprising a first non-reciprocal optical rotator (NRR) and a first reciprocal optical rotator (RR); a second PBS optically coupled to the first set of optical rotators at a side opposite to the first PBS; a first reflection interferometer (RI) optically coupled to the second PBS at a face intersecting a second axis of the device, wherein the second axis is not parallel to the first axis; a second RI optically coupled to the first PBS at a face intersecting a third axis of the device, wherein the third axis is not parallel to the first axis; a second set of optical rotators optically coupled to the second PBS at a side opposite to the first RI, the second set of optical rotators comprising a second NRR and a second RR; a third PBS optically coupled to the second set of optical rotators at a side opposite to the second PBS; and a third RI optically coupled to the third PBS at a side opposite to the second set of optical rotators.