HIGH-ISOLATION POLARIZATION-INSENSITIVE OPTICAL CIRCULATOR FOR ADVANCED OPTICAL COMMUNICATION-SYSTEMS

This paper describes a novel optical circulator configuration that doesn't employ any polarization beam-splitters (PBS's). Birefringent crystals (BC's) are used instead of PBS's to achieve a high-isolation polarization-insensitive optical circulator. The use of BC's simplifies fabrication. A conceptual configuration and two concrete structures are proposed. The prototype optical circulator is tested and exhibits over 60 dB of isolation in the wavelength range of 70 nm around 1550 nm. The insertion loss is under 1.5 dB and fluctuates only 0.2 dB with changes in the polarization state.