Co-wavelength-channel integration of ultra-low-frequency distributed acoustic sensing and high-capacity communication

Integrating distributed ultra-low-frequency vibration sensing and high-speed fiber optical communication can provide additional functionality under the current submarine telecommunication network, such as ocean seismic monitoring and geological exploration. This work demonstrates an integrated sensing and communication (ISAC) system utilizing the same wavelength channel over a 38 km seven-core fiber for concurrent large-capacity transmission and ultra-low-frequency distributed acoustic sensing. Specifically, the digital subcarrier multiplexing (DSM) signal and the chirped-pulse sensing signal are frequency division multiplexed at the same wavelength channel, under the condition of the optimal protection interval bandwidth, relying on the DSM flexibility in spectral allocation. As a result, we successfully achieve a sensitivity of both 3.89 nε/ Hz @0.1 Hz and 0.18 nε/ Hz @10 Hz under a spatial resolution of 20 m, under the framework of direct detection and cross-correlation demodulation. Meanwhile, a transmission capacity record of 241.85 Tb/s is secured for the ISAC when wavelength and space division multiplexed DP-16QAM DSM signals are successfully transmitted to reach the 20% soft-decision feedforward correction coding threshold of 2×10 −2 .