| 摘要 |
PROBLEM TO BE SOLVED: To warrant reliable service in a large capacity optical fiber network by selecting a response time required for dynamic gain control of an optical amplifier so as to be inversely proportional substantially to the number of optical amplifiers in a communication path. SOLUTION: An erbium doped fiber amplifier 16 is one of chains in existence along a communication link. λ1 ... λn depict wavelength multiplex a plurality of channels. A check and control signal λ0 generated from a laser light source 20 and passing through a saturation absorbing body 26 is fed to the amplifier 16 via a 3-port optical circulator 22 and photocoupler pairs 24, 25. When the communication link loses part of channels and the gain of the amplifier is increased, the saturation absorbing body 26 makes it possible to give the signal λ0 more to the amplifier 16, resulting that the increase in the amplifier gain is slight. Since the reply control is implemented at a very high speed, even in the case of a large scale optical network where 100 optical amplifiers are connected longitudinally, the response time of gain control is selected to be in the order of 5μs or below. |
