| 摘要 |
PURPOSE:To simplify a transmission line and to improve the privacy telephone properties by connecting a main communication equipment and plural wave length multiplexing/demultiplexing means together in a ring shape via an optical fiber and then connecting plural nodes to the multiplexing/demultiplexing means corresponding to each specific wavelength. CONSTITUTION:The signal light is inputted to an optical circulator 22-1 from a wavelength multiplexer 13 via an optical fiber 21 and outputted to the fiber 21. At the same time, only the signal light of the wavelength assigned to a node 30-1 is extracted by a filter 23-1. Meanwhile the signal light of other wavelengths are returned to the circulator 22-1 and outputted to a circulator 22-2. The extracted signal light is sent to a receiving device 33-1 and received there. The node 30-1 transmits the necessary information from a light source 32-1 by the signal light of the same wavelength. Then the information is inputted to the circulator 22-1 through the filter 23-1. In such a way, the fiber 21 is provided in a ring shape and the communication is possible between the optical circulator and the node. Furthermore a filter is added to the fiber 21 so that a transmission line is simplified and the privacy telephone properties can be improved. |
