LIGHT FREQUENCY ADDING AND DROPPING CIRCUIT AND LIGHT FREQUENCY MULTIPLEX NETWORK USING IT

摘要

PROBLEM TO BE SOLVED: To make a light frequency adding and dropping circuit suitable for bi-directional transmission and to reduce a circuit scale by outputting an optical signal from an input port to a second optical port, outputting a reflected optical signal to a third optical port and furthermore outputting the reflected signal to a fourth optical port. SOLUTION: A signal from an input port 600 is routed to an output port 604 by the operation of an optical circulator 602 and inputted to an optical band-pass filter 605. Only the optical signal of a specific light frequency is transmitted through this and the residual light frequencies are reflected. As a result, the optical signal of a specific channel is outputted to a drop signal output port 607 through an optical isolator 606 preventing reflection caused by a connecting connector and the optical signals of the residual channels are reflected in the direction of the circulator 602. Next the reflected signal is routed to an input port 603 by the operation of the circulator 602 and inputted to an optical band pass filter 608. Similarly, a frequency which does not coincide here is made to enter an input port 601 by the circulator 602.