OPTICAL TRANSMISSION SYSTEM

摘要

An optical transmission system comprises a communication center including a transmitter-receiver for transmitting and receiving optical signals, and a plurality of terminals which communicate with the communication center. The system also comprises a plurality of node devices provided between the communication center and the terminals. The plurality of node devices convert optical signals from the communication center into electrical signals for transmission to the terminals and convert electrical signals from the terminals into optical signals for transmission to the communication center. Each of the plurality of node devices is connected to a group of the terminals. The group of the terminals which are connected to one of the node devices sends information to said communication center by digital modulated electrical signals. Each of the node devices comprises a light-emitting element in which a bias point is at or near a threshold for light emission.