Optical submarine branching device

摘要

An optical submarine branching unit employing an optical circuit structure which is small in the number of optical components used, permits reduction of optical insertion loss and is well compatible with the ADD/DROP function suitable for use in wavelength multiplex transmission. An optical fiber pair provided in an optical submarine cable connecting between first and second points is branched toward a third point, an optical circulator capable of reversing the direction of rotation of an optical input/output is provided as optical switching means by which, in the event of a failure in the branch transmission system having the branched optical fiber pair, the optical fiber pair is connected between the first and second points directly without being branched to the third point.