Real time dynamic strain monitoring of optical links using the backreflection of live PSK data
AuthorsFidalgo Martins, Hugo; Shi, K.; Thomsen, B.C.; Martín López, Sonia; González Herráez, Miguel; [et al.]
Optical Society of America
Ministerio de Economía y Competitividad
Comunidad de Madrid
H. F. Martins, K. Shi, B. C. Thomsen, S. Martin-Lopez, M. Gonzalez-Herraez, and S. J. Savory, "Real time dynamic strain monitoring of optical links using the backreflection of live PSK data," Opt. Express 24, 22303-22318 (2016).
Fiber optics communications
Fiber optics sensors
info:eu-repo/grantAgreement/EC/FP7/307441/EU/Ubiquitous optical FIbre NErves/U-FINE
info:eu-repo/grantAgreement/MINECO/TEC2013-45265-R/ES/DETECCION TEMPRANA DE AMENAZAS PARA INFRAESTRUCTURAS CRITICAS USANDO SISTEMAS DISTRIBUIDOS DE FIBRA OPTICA/
info:eu-repo/grantAgreement/Comunidad de Madrid//S2009%2FMIT2790/ES/Sensores e INstrumentación en tecnologías FOTÓNicas/SINFOTON
info:eu-repo/grantAgreement/EC/FP7/608099/EU/Allied Initiative for Training and Education in Coherent Optical Networks/ICONE
Attribution Creative Commons Non Commercial No Derivatives 3.0 CC-BY-NC-ND-3.0
(c) Optical Society of America, 2016
A major cause of faults in optical communication links is related to unintentional third party intrusions (normally related to civil/agricultural works) causing fiber breaks or cable damage. These intrusions could be anticipated and avoided by monitoring the dynamic strain recorded along the cable. In this work, a novel technique is proposed to implement realtime distributed strain sensing in parallel with an operating optical communication channel. The technique relies on monitoring the Rayleigh backscattered light from optical communication data transmitted using standard modulation formats. The system is treated as a phase-sensitive OTDR (ΦOTDR) using random and non-periodical non-return-to-zero (NRZ) phase-shift keying (PSK) pulse coding. An I/Q detection unit allows for a full (amplitude, phase and polarization) characterization of the backscattered optical signal, thus achieving a fully linear system in terms of ΦOTDR trace coding/decoding. The technique can be used with different modulation formats, and operation using 4 Gbaud single-polarization dual PSK and 4 Gbaud dual-polarization quadrature PSK is demonstrated. As a proof of concept, distributed sensing of dynamic strain with a sampling of 125 kHz and a spatial resolution of 2.5 cm (set by the bit size) over 500 m is demonstrated for applied sinusoidal strain signals of 500 Hz. The limitations and possibilities for improvement of the technique are also discussed.