Polarization–wavelength-multiplexed ISAC networks enabled by hybrid Raman amplification and diversity reception

Abstract

We propose an integrated sensing and communication (ISAC) architecture capable of simultaneously performing distributed acoustic sensing (DAS) and distributed temperature sensing (DTS) in a single-mode fiber (SMF) and experimentally evaluate its coexistence feasibility using a discrete-component proof-of-concept setup. This system supports parallel multi-parameter sensing based on phase-sensitive optical time-domain reflectometry ($\phi$-OTDR) and Raman optical time-domain reflectometry (ROTDR). The present experiment is conducted using discrete commercial components, while integrated polarization–wavelength de/multiplexing is retained only as a possible future compact implementation route. Hybrid amplification techniques, including Raman distributed amplification and optical-bias-assisted superimposed enhancement, are introduced to improve the communication link budget and ROTDR detectability under a reduced sensing-probe power. In addition, polarization-diversity reception is analyzed as a potential extension to mitigate polarization fading and improve the stability of Rayleigh-based vibration sensing. Experimental results demonstrate system-level coexistence of $\phi$-OTDR-based DAS, ROTDR-based DTS, and single-polarization 2.5 Gbit/s non-return-to-zero/intensity-modulation direct-detection (NRZ/IMDD) communication over a 10 km SMF link. The simplified proof-of-concept experiment achieves a spatial resolution of 5 m, a temperature uncertainty of 2.8°C, and a vibration-sensing signal-to-noise ratio (SNR) of 12.1 dB under a sensing-probe peak power of 100 mW, while no bit errors are observed in the communication branch during the experimental test. Fiber-optic communication and sensing integration technology can support traditional applications such as oil and gas pipelines, power lines, and environmental monitoring, and may provide useful sensing capability for emerging scenarios such as digital twins and intelligent optical networks.