| 摘要 |
PURPOSE:To miniaturize the scale of a center station device, by providing a first Y type optical coupler and a second Y type optical coupler on every subscriber, and using light of the same wavelength as an up signal and a down signal between a center and each subscriber. CONSTITUTION:The first Y type optical coupler 15 is inserted to a trunk system optical fiber 11, and branches the down signal from the center to a trunk system optical fiber 12 of succeeding order and a subscriber system optical fiber 14 corresponding to the subscriber, and also, fits the up signal from the optical fiber 14 to the trunk system optical fiber 12. The second Y type optical coupler 16 is provided between the subscriber optical fiber 14 and the subscriber 13, and transmits the down signal from the subscriber system optical fiber 14 to the subscriber 13, and also, couples the up signal from the subscriber 13 to the optical fiber 14. In such a way, it is possible to connect all of the subscribers to one optical fiber, and also it is enough to prepare only one kind of light emitting element or light receiving element since the wavelength of a transmission signal and a reception signal are same, thereby, constitution can be simplified. |
