Monitoring signal light output apparatus, submarine apparatus, and optical communication system

A submarine apparatus comprising:

• a first optical demultiplexer inserted into a first optical fiber included in a submarine optical cable and configured to demultiplex a first monitoring signal light transmitted by the first optical fiber;
• a second optical demultiplexer inserted into a second optical fiber that is included in the submarine optical cable and transmits a signal light in a direction opposite to the first optical fiber, and configured to demultiplex a second monitoring signal light transmitted by the second optical fiber;
• a semiconductor optical amplifier configured to amplify the first monitoring signal light separated by the first optical demultiplexer and modulate the first monitoring signal light, amplify the second monitoring signal light separated by the second optical demultiplexer and input in a direction opposite to the first monitoring signal light, and modulate the second monitoring signal light;
• a control unit configured to output a control signal indicating a state of the submarine apparatus;
• a drive unit configured to output a drive signal to the semiconductor optical amplifier in response to the control signal to perform modulation operations of the first and second monitoring signal lights;
• a first optical multiplexer configured to multiplex the first monitoring signal light amplified and modulated by the semiconductor optical amplifier to a signal light transmitted by the first optical fiber;
• and
• a second optical multiplexer configured to multiplex the second monitoring signal light amplified and modulated by the semiconductor optical amplifier to the signal light transmitted by the second optical fiber.

An optical communication system comprising:

• a submarine optical cable connecting a first optical transmission apparatus and a second optical transmission apparatus;
• and
• a submarine apparatus inserted into the submarine optical cable, wherein
• the submarine apparatus comprises:
• a first optical demultiplexer inserted into a first optical fiber included in the submarine optical cable, and configured to demultiplex a first monitoring signal light output from the first optical transmission apparatus and transmitted through the first optical fiber;
• a second optical demultiplexer inserted into a second optical fiber that is included in the submarine optical cable and transmits a signal light in a direction opposite to the first optical fiber, and demultiplex a second monitoring signal light output from the second optical transmission apparatus and transmitted through the second optical fiber;
• a semiconductor optical amplifier configured to amplify the first monitoring signal light separated by the first optical demultiplexer and modulate the first monitoring signal light, amplify the second monitoring signal light separated by the second optical demultiplexer and input in a direction opposite to the first monitoring signal light, and modulate the second monitoring signal light;
• a control unit configured to output a control signal indicating a state of the submarine apparatus;
• a drive unit configured to output a drive signal to the semiconductor optical amplifier in response to the control signal to perform modulation operations of the first and second monitoring signal lights;
• a first optical multiplexer configured to multiplex the first monitoring signal light amplified and modulated by the semiconductor optical amplifier to a signal light transmitted by the first optical fiber and output a multiplexed signal light to the second optical transmission apparatus;
• and
• a second optical multiplexer configured to multiplex the second monitoring signal light amplified and modulated by the semiconductor optical amplifier to the signal light transmitted by the second optical fiber and output a multiplexed signal light to the first optical transmission apparatus.