Patent ID: 7430372

Claim:
An optical transmission system for making transmission of an optical signal, comprising: a first node having a post-amplifier to output noise light to an optical fiber in an amplifier booting mode and to amplify an optical signal and to output the amplified optical signal to an optical fiber in a working mode and an operational state informing unit to inform an operational state of the post-amplifier by using a monitoring control signal; and a second node having a pre-amplifier to receive the noise light and to do gain setting in the amplifier booting mode and to receive the optical signal and to amplify the received optical signal in the working mode, a variable dispersion compensator placed in a preceding-stage of the pre-amplifier to make, in a variable manner, compensation of dispersion of a wavelength caused by propagation of the optical signal through an optical fiber, a switching unit to select, when the noise light passes through the variable dispersion compensator, if a level of the noise light is deviated from a desired level, a bypass route so as to make the noise light not be input to the variable dispersion compensator but be input to the pre-amplifier according to a switching instruction in the amplifier booting mode and to select a passage route so as to make the optical signal, after having been input to the variable dispersion compensator and having undergone dispersion compensation, be input to the pre-amplifier according to a switching instruction in the working mode, and a switch controller to output, when the amplifier booting mode is recognized by the monitoring control signal, the switching instruction signal to select the bypass route and, in the working mode, to output the switching instruction signal for selection of the passage route.