Wavelength-division multiplexing transmission device

A wavelength-division multiplexing transmission device including a receiver and a transmitter, the receiver being configured to demultiplex wavelength-division multiplexed light received by said device and configured to demodulate one of the demultiplexed light to output reception data while passing another one of the demultiplexed light through said receiver, the transmitter being configured to transmit wavelength-division multiplexed light generated by multiplexing light of wavelengths which have been modulated based on transmission data and light of a wavelength passed through by the receiver, the wavelength-division multiplexing transmission device comprising:

• a dummy light source configured to emit and quench dummy light;
• a monitoring unit configured to monitor an optical level relating to the received wavelength-division multiplexed light;
• a dummy light controller configured to control the dummy light source to emit dummy light in case where the monitoring unit determines based on the monitored optical level that the wavelength-division multiplexed light is in a condition of input interruption;
• and
• a multiplexer configured to multiplex the light of the wavelength modulated based on the transmission data and the dummy light emitted by the dummy light source, wherein
• the transmitter transmits wavelength-division multiplexed light generated by the multiplexer.