Patent ID: 7039325

Claim:
A communication system for controlling optical communication, the system comprising: a sending unit including: supervisory signal sending control means for controlling the sending of a supervisory signal for having supervisory control of optical communication and a drive supervisory signal for controlling the driving of a Raman optical fiber amplifier for performing Raman optical amplification by using a non-linear optical phenomenon in an optical fiber, and sending stop means for receiving a stop signal and for stopping the sending of the drive supervisory signal; and a receiving unit including: the Raman optical fiber amplifier, drive control means for receiving the drive supervisory signal and for controlling the driving of the Raman optical fiber amplifier, and stop signal sending means for sending the stop signal to the sending unit after the Raman optical fiber amplifier being driven; wherein the supervisory signal sending control means sets a transmission rate of the drive supervisory signal to a minimized value and sends the drive supervisory signal so that the drive supervisory signal can be received in a state in which the Raman optical fiber amplifier is not operating; and a bit rate B OSC2 of the drive supervisory signal is given by B OSC2 =B OSC1 /10^( G DRA@OSC1 /10) where 10^A=10 A , wherein B OSC1 is a bit rate of the supervisory signal and G DRA@OSC1 is a gain of the Raman amplifier for the supervisory signal.