Integration of communication and distributed sensing over optical supervisory channel using live QPSK streams

The rapid development of wavelength-division multiplexing (WDM) systems has underscored the critical requirement for effective link monitoring to ensure system reliability and performance. Traditional approaches often rely on separate devices for communication and sensing, which can compromise spectral efficiency and increase system complexity. This work presents an innovative method for integrating communication and sensing within a conventional optical supervisory channel. Four QPSK data streams with different duty ratios enable robust communication and precise sensing with a 125-MBaud transmitter. The forward transmission of communication signals is demonstrated with impeccable accuracy, delivering bit-error-free performance over two fiber links. Concurrently, sensing data is extracted through polarization-diversity reception of the backscattering signal. The distributed acoustic sensing sensitivity achieves 0.50 nε/√Hz in 10.2 km and 0.65 nε/√Hz in 40.0 km at a spatial resolution of 10 m by employing a matched filter. This approach effectively adopts the defined forwarded transmitted control signals or channel information signals, such as channel power, optical signal-to-noise ratio, and Q-factor, simultaneously achieving sensing applications without any dedicated channel or resource.