Patent ID: 7003191

Claim:
An optical switch provided with N number of input ports and N number of output ports (herein “N” is a plural number), comprising: N number of first switching parts each having one input port of the N number of input ports and N number of first coupling ports; N number of second switching parts each having one output port of the N number of output ports, N number of second coupling ports; and N×N number of optical fibers connecting the first coupling ports and the second coupling ports, wherein P 1 i each of half the number or more of first coupling ports the N×N first coupling ports are connected with second coupling ports P 2 (N+1−i), where P 1 i is a first coupling port corresponding to an optical path which comes in the “i”th shortest one in terms of the optical path length between the input port and one of the first coupling ports in each first switching part, and P 2 j is a second coupling port corresponding to the “j”th shortest one in terms of the optical path length between the output port and one of the second coupling ports in each second switching part, wherein the optical path length from the input port to the output port in the respective N×N number of optical paths is substantially the same.