Patent ID: 6980745

Claim:
An optical transmission system comprising: an end station including a monitor instruction sending unit for sending a monitor instruction for monitoring an operating condition of a repeater, and an operating condition recognizing unit for receiving a response signal from the repeater and recognizing the operating condition; and a repeater including: a filtering unit filtering the monitor instruction and the response signal; a monitor control unit monitoring the operating condition of the repeater in response to the monitor instruction and generating response information that is a result of monitoring; a pump unit applying a pump light to an optical fiber transmission medium and enabling an optical amplification using the optical fiber transmission medium as an amplifying medium; a regeneration control unit performing a regeneration control of the response signal sent by another repeater to thereby generate a regenerated signal; a modulation control unit modulating the pump light by the response information or the regenerated signal to generate the response signal, and modulating another pump light by the response information or the regenerated signal to generate the response signal, said another pump light being in the direction reverse to a pumping direction, so as not to cause forward Raman amplification and to be receivable by an adjoining repeater, when the response signal travels in a direction identical to that in which an optical main signal travels; and a photocoupler unit that is connected to the optical fiber transmission medium and sends the response signal in a direction identical to or reverse to that in which the optical main signal travels.