Simplified Design of Multiport Optical Circulator With Parallel Connection of Mirror-Image Arranged Spatial- and Polarization-Modules

This letter proposes a simplified design of multiport optical circulator with parallel connection of mirror-image arranged spatial- and polarization-modules. To show the feasibility of the design, a prototype of six-port optical circulator was fabricated. The insertion losses are 0.51-1.05 dB, the isolations are 26.20-45.13 dB, and return losses are 27.72 dB. This design should bear merits of a simple and symmetric structure that is low cost, easily fabricated, polarization-independent, and polarization-mode dispersion resolved, and exhibits high performance.