OPTICAL COUPLER AND METHOD FOR BRANCHING LIGHT USING OPTICAL COUPLER

摘要

[Problem] To provide an optical coupler capable of branching light with a desired branching rate when necessary, and a method for branching light using the optical coupler. [Solution] An optical coupler (1) is provided with an input optical fiber (10) having a thin diameter part (12) formed with a relatively thin outer diameter at a portion in the length direction thereof and branching light transmitted thereto at the thin diameter part (12); and an output fiber (20) for receiving the light branched from the input optical fiber (10). The thin diameter part (12) of the input optical fiber (10) is brought into contact with a thin diameter part (22) of the output optical fiber (20). The branching rate (S) of the light branched from the input optical fiber (10) to the output optical fiber (20) varies with a change in the contact length between the thin diameter part (12) of the input optical fiber (10) and the thin diameter part (22) of the output optical fiber (20) or the propagation constant for the optical fiber.