Patent ID: 7043100

Claim:
A polarization independent optical isolator/circulator based on a nonreciprocal phase shifter comprising: first and second Mach-Zehnder waveguide interferometers, each having an input port and an output port, and each one having two interferometer arms, with nonreciprocal phase shifters in the interferometer arms; said phase shifters comprising a plurality of half-wave retarders or quarter wave retarders; and one or more Faraday rotators with a total rotation of 45°, wherein the slow axes of the retarders are either parallel or perpendicular to each other so that with phase or power compensation between the two paths by either active or passive means, a light that enters through one of the input ports is split in the first interferometer into two linearly polarized components and recombined into one of the output ports in the second interferometer.