Optical communication system

An optical communication system comprising:

• a plurality of transmitters each to perform error correction encoding on information to be transmitted, and to output a result of the error correction encoding in a form of an optical signal, the error correction encoding enabling correction performance to be provided that is dependent on a number of iterations of decoding;
• a plurality of first optical couplers provided correspondingly to the plurality of respective transmitters, each to branch, at an asymmetric branching ratio, the optical signal output by a corresponding one of the transmitters, and to output a first optical signal corresponding to a highest branching ratio and a second optical signal corresponding to a non-highest branching ratio;
• a plurality of receivers each to receive at least one optical signal of the first optical signal or the second optical signal;
• a plurality of second optical couplers provided correspondingly to the plurality of respective receivers, each to couple together a plurality of ones of the optical signals output by corresponding respective ones of the plurality of first optical couplers, and to input a resulting optical signal into a corresponding one of the receivers;
• an error correction decoding circuitry provided correspondingly to each of the plurality of receivers to perform error correction decoding on the at least one optical signal received by a corresponding one of the receivers as many times as a number of iterations that has been set;
• and
• a communication disconnection detection circuitry to, upon detection of a disconnection of communication of the first optical signal, notify, of the disconnection of communication, the error correction decoding circuitry that is to process the second optical signal branched from an optical signal common to the first optical signal, wherein
• a plurality of optical signals obtained by branching from a common optical signal are received by different ones of the receivers,
• the error correction decoding circuitry that is to process the second optical signal does not perform error correction decoding on the second optical signal during normal operation in which no notification has been received of the disconnection of communication, but performs error correction decoding on the second optical signal when a notification of the disconnection of communication has been received, and
• the error correction decoding circuitry that processes the first optical signal performs the error correction decoding with a smaller number of iterations than a number of iterations used by the error correction decoding circuitry that processes the second optical signal.