Study of Raman amplification in DPP-BOTDA sensing employing Simplex coding for sub-meter scale spatial resolution over long fiber distances

Abstract The impact of Raman amplification and Simplex coding is studied in combination withdifferential pulse-width pair Brillouin optical time-domain analysis (DPP-BOTDA) to achievesub-meter spatial resolution over very long sensing distances. An optimization of the powerlevels for the Raman pumps, Brillouin pump and signal has been carried out through numericalsimulations, maximizing the signal levels and avoiding at the same time nonlinear effects andpump depletion. A reduction of acoustic-wave-induced distortions in the Brillouin gainspectrum down to negligible levels has also been achieved by numerical optimization of thepulse width and duty cycle of return-to-zero Simplex coding, providing significantsignal-to-noise ratio enhancement. Strain–temperature sensing over 93 km standard SMF isachieved with a strain / temperature accuracy of 34 μe/ 1.7 ◦ C, and 50 cm spatial resolutionthroughout the fiber length. Keywords: fiber optics, sensors, Brillouin scattering, coding(Some figures may appear in colour only in the online journal)

[1]  Marcelo A. Soto,et al.  Long-range BOTDA sensing using optical pulse coding and single source bi-directional distributed Raman amplification , 2011, 2011 IEEE SENSORS Proceedings.

[2]  Fabrizio Di Pasquale,et al.  Optimization of long-range BOTDA sensors with high resolution using first-order bi-directional Raman amplification. , 2011, Optics express.

[3]  Fabrizio Di Pasquale,et al.  Optimization of a Dpp-botda Sensor with 25 Cm Spatial Resolution over 60 Km Standard Single-mode Fiber Using Simplex Codes and Optical Pre-amplification References and Links High Spatial Resolution and Long-distance Botda Using Differential Brillouin Gain in A , 2022 .

[4]  Pedro Corredera,et al.  Distributed Brillouin Fiber Sensor Assisted by First-Order Raman Amplification , 2010, Journal of Lightwave Technology.

[5]  X. Bao,et al.  High-resolution DPP-BOTDA over 50 km LEAF using return-to-zero coded pulses. , 2010, Optics letters.

[6]  M.D. Jones,et al.  Using simplex codes to improve OTDR sensitivity , 1993, IEEE Photonics Technology Letters.

[7]  G. Bolognini,et al.  Transient effects in gain-clamped discrete Raman amplifier cascades , 2004, IEEE Photonics Technology Letters.

[8]  Nicholas Ioannides,et al.  Approaches to mitigate polymer-core loss in plastic optical fibers: a review , 2014 .

[9]  Yongkang Dong,et al.  Differential Brillouin gain for improving the temperature accuracy and spatial resolution in a long-distance distributed fiber sensor. , 2009, Applied optics.

[10]  G. Bolognini,et al.  Bidirectional higher order cascaded Raman amplification benefits for 10-Gb/s WDM unrepeated transmission systems , 2005, Journal of Lightwave Technology.

[11]  Hosung Yoon,et al.  Analysis and experimental demonstration of simplex coding technique for SNR enhancement of OTDR , 2004, Proceedings of the Lightwave Technologies in Instrumentation and Measurement Conference, 2004..