Integrated Communication and In-Band Spectrum Polarization-Based Sensing via Fraction-Division Non-Orthogonal Multiple Access

We have proposed and experimentally validated an integrated scheme of in-band spectrum polarization sensing and standard coherent communication via fraction-division non-orthogonal multiple access (FD-NOMA). Processed through fractional Fourier transform (FrFT), the chirp-based sensing probe is superimposed onto telecom payload in an orthogonal polarization state. The temporal and spectrum resources originally intended for telecom are utilized for forward sensing. By leveraging energy-compaction property of FrFT, the sensing probe can converge to fractional peak while telecom payload remains dispersed. Therefore, the sensing probe and telecom payload are orthogonal to each other in matched fraction domain. The energy distribution of fractional peak between orthogonal SOPs can be obtained to achieve vibration-induced SOP sensing. The feasibility of integration of in-band spectrum sensing and communication is verified by an experiment of bidirectional 480 Gb/s DP-16QAM transmission over 32.5 km fiber. To mitigate probe-induced impact, successive interference cancellation (SIC) involving matched de-chirping is proposed to improve optical signal to noise ratio (OSNR) penalty from more than 3.0 dB to 0.7 dB. Experimental results of sensing performance demonstrate that the signal-to-noise ratio (SNR) of recovered vibration waveform using FD-NOMA deteriorates by less than 0.9 dB as OSNR degrades from 26 dB to 18 dB. In contrast, conventional adaptive equalization exhibits severe SNR penalty of approximately 8.9 dB. The sensitivity and the limit of detection (LoD) are 5.3 × 10⁻³rad/μϵ and 70.7 nϵ/√Hz respectively, with vibration localization error equivalent to 8 m.