Abstract

Optical circulators will play an important role in future advanced optical communication systems.^1,3 We have already proposed a high-isolation structure for optical nonreciprocal devices without any polarization beam splitters (PBSs).⁴ However, because a beam cannot be freely propagated between all pairs of ports, the structure cannot create a perfect optical circulator. This paper proposes a perfect structure for high-isolation optical circulators without any PBSs. Birefringent crystals (BCs) make the circulator polairization-insensitive and achieve circular propagation. The BCs eliminate the need for precise angle adjustment during assembly; consequently, high. Isolation is. achieved with easy fabrication.

© 1992 Optical Society of America