Optical transmission system

An optical transmission device for making transmission of an optical signal, comprising:

• a pre-amplifier to receive noise light output from a post-amplifier in a preceding-stage node and to do gain setting in an amplifier booting mode and to receive an optical signal output from the post-amplifier and to amplify the optical signal in a 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 an amplifier booting 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 a working mode;
• and
• a switch controller to output, when an amplifier booting mode is recognized by the monitoring control signal which was transmitted from the preceding-stage node and showed an operational state of the post-amplifier, the switching instruction signal to select the bypass route and to output the switching instruction signal to select the passage route in a working mode.

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 in a working mode;
• and
• a second node having a pre-amplifier to receive noise light and to do gain setting in an amplifier booting mode and to receive an optical signal and to amplify the received optical signal in an 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 light level detector to detect light levels on input and output sides of the variable dispersion compensator, 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, according to a switching instruction, so as to make the noise light not be input to the variable dispersion compensator but be input to the pre-amplifier in an amplifier booting mode and to select a passage route, according to a switching instruction, 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 in a working mode, and a switch controller to obtain a threshold value by estimating a receiving level of each of one wave of the optical signal and the noise light output from the post-amplifier from the light level and to recognize an amplifier booting mode or a working mode, based on the threshold value, and to output the switching instruction signal corresponding to each mode.

An optical transmission device for making transmission of an optical signal, comprising:

• a pre-amplifier to receive noise light output from a post-amplifier in a preceding-stage node and to do gain setting in an amplifier booting mode and to receive an optical signal output from the post-amplifier and to amplify the optical signal,
• 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 light level detector to detect light levels on input and output sides of the variable dispersion compensator,
• 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 an 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 a working mode;
• and
• a switch controller to obtain a threshold value by estimating a receiving level of each of one wave of the optical signal and the noise light output from the post-amplifier from the light level and to recognize an amplifier booting mode or a working mode, based on the threshold value, and to output the switching instruction signal in a manner to correspond to each mode.

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
• a second node having a pre-amplifier to receive noise light and to do gain setting in an amplifier booting mode and to receive an optical signal and to amplify the received optical signal in an 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 spectrum detector to detect an optical spectrum on an input side of the variable dispersion compensator, 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 in an amplifier booting mode according to a switching signal 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 in a working mode, and a switch controller to recognize an amplifier booting mode or a working mode based on the optical spectrum and to output the switching signal in a manner to correspond to each mode.

An optical transmission device for making transmission of an optical signal, comprising:

• a pre-amplifier to receive noise light output from a post-amplifier in a preceding-stage node and to do gain setting in an amplifier booting mode and to receive an optical signal output from the post-amplifier and to amplify the optical signal in a 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 spectrum detector to detect an optical spectrum on an input side of the variable dispersion compensator,
• 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 in an amplifier booting mode according to a switching instruction and to select a passage route so as to make the optical signal, 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 a working mode;
• a switch controller to recognize an amplifier booting mode or a working mode based on the optical spectrum and to output the switching signal in a manner to correspond to each mode.