Optical branching device for short distance optical communication

PURPOSE:To make a device compact, and to attain a low cost without taking an expensive countermeasure by using a waveguide path with a photosensitive glass as a base for the optical branching part or optical multiplexer of an optical branching device using a multimode optical fiber. CONSTITUTION:A connecting part 7 of an optical branching part 6 with a multimode optical fiber 1 is the waveguide path with the photosensitive glass as a base, the size of the core of the cross-section is 200mum square, and the circumstance is coated with a transparent resin as a clad layer. Normally, an optical signal transmitted through a first optical fiber 1 is converted into an electric signal by an optic/electric converter 2, and processed by a signal processing part 4, or it is directly converted into the optical signal by an electro/ optic converter 3, and transmitted to a second optical fiber 12 and the next node. At that time, even when the power source of the node is disconnected, and a communication can not be attained, the optical signal is directly transmitted through the branched waveguide path 9 to the second optical fiber 12, so that the occurrence of a fault can be prevented as an entire communication network.