Polarization-independent optical circulator having high isolation over a wide wavelength range

The letter proposes a new structure of a polarization-independent optical circulator. It is theoretically and experimentally shown that the proposed circulator has high isolation over a wide wavelength range. Insertion loss and isolation of a fabricated four-part circulator have been measured to beor=42.3 dB, respectively. Loss ratio over 40.4 dB has been realized.>