OPTICAL COUPLING NONRECIPROCAL DEVICE

摘要

The optical nonreciprocal device is used to optically couple together two opposed optical fibers. The light from one optical fiber is separated into ordinary ray and extraordinary ray by a first birefringent crystal member. The separated ordinary and extraordinary rays are subject to a total of 90.degree. polarization rotation by transmitting in a forward direction through a magneto-optical member having an angle of polarization rotation of 45.degree. and through a compensating plate. The separated ordinary and extraordinary rays are synthesized by transmitting through a second birefringent crystal member and then applied to the other optical fiber. A lens is interposed between one optical fiber and the first birefringent crystal member for causing the light to propagate through the light path while being converged or diverged. By suitably selecting the thicknesses of the first and second birefringent crystal members, the ordinary and extraordinary rays propagating from the second optical fiber to the first optical fiber in the reverse direction are prevented from being overlapped at the incident end of the first optical fiber thus providing an optical isolator.