Computationally efficient stokes-domain phase demodulation for polarization-diversity coherent $$\phi$$-OTDR with apache flink stream processing
Year: 2026
Type: article
Abstract: Distributed acoustic sensing (DAS) based on phase-sensitive optical time-domain reflectometry ( \(\phi\) -OTDR) enables distributed vibration detection over long optical fibres. We investigate a computationally efficient Stokes-domain demodulation approach for polarization-diversity coherent \(\phi\) -OTDR. The Stokes representation provides access to the polarization phase, orientation, and ellipticity, which depend on different combinations of the Stokes parameters and therefore exhibit different conditioning under polarization variations. The state-of-polarization (SOP) evolution is further characterized using the degree of polarization (DOP) and Poincaré-sphere representation, enabling visualization of the polarization behaviour under vibration-affected, silent-fibre, and noise-floor conditions. The polarization phase, derived from the ratio of two Stokes parameters, is demonstrated to be equivalent to the differential phase between orthogonal polarization components while requiring only a single Stokes-domain phase computation, thereby reducing computational complexity. The method is experimentally evaluated over a 10.15-km fibre using 100-ns pulses with a 120- \(\mu \text {s}\) repetition period, providing approximately 10-m spatial resolution and a Nyquist-limited maximum detectable vibration frequency of 4.17 kHz. Experimentally investigated vibrations from 400 Hz to 3 kHz yielded spectral SNRs of 29.50 dB and 23.98 dB, respectively, while a 2-kHz vibration was localized near 10.11 km with a peak SNR of 27.14 dB. A proof-of-concept Apache Flink implementation demonstrates reduced processing time for Stokes-domain phase extraction relative to differential-phase processing under the same local execution environment. The three Stokes-derived angular observables exhibit different conditioning under polarization imbalance, while deep Rayleigh interference fading can degrade all of them as the total backscattered signal approaches the receiver-noise level.
Source: Scientific Reports
Authors: Almaz Demise, Abdusomad Nur, Yonas Muanenda
Institutions: Scuola Superiore Sant'Anna, Addis Ababa University
Language: English
Topic: Advanced Fiber Optic Sensors
Subfield: Electrical and Electronic Engineering
Field: Engineering
Domain: Physical Sciences
Open Access status: gold
Estimated APC paid: $2,690
OpenAlex ID: W7223401727