A polarization-independent optical circulator for 1.3 µm

A compact polarization-independent optical circulator for 1.3μm is described. The device utilizes birefringent plates (rutile) for beam splitting, YIG plus a single-order quartz half-wave plate for polarization rotation, and a slotted 45° glass prism for beam steering. The fiber-to-fiber insertion loss is 2.0 or 2.5 dB and the isolation is 25 or 35 dB, depending upon the ports in question. The use of birefringent plates for beam splitting and combining eliminates the need for multiple dielectric coatings for polarization beam splitting, requires only optical plate processing, virtually eliminates sensitivity to translational misalignment of individual beam-splitting/combining components, and reduces the required number of optical-quality surfaces.