Abstract

Time-expanded phase sensitive (TE-φ)OTDR is a recently reported technique for distributed fiber sensing that relies on the use of an electro-optic dual frequency comb (DFC) scheme. A distinctive feature of this approach is its ability to provide high spatial resolution (on the centimeter scale) with detection bandwidths orders of magnitude lower than those of conventional φOTDR systems. The stringent trade-off between resolution, range and sensing bandwidth that exists in TE-φOTDR has demonstrated to be substantially relaxed by implementing two frequency combs with quasi-integer-ratio repetition rates. However, employing very dissimilar line separations (with a ratio between them >100) is challenging due to the need of keeping the coherence over long sequences of interferograms, which eventually limits the attainable range. In this paper, we formulate the requirements for the frequency stability of the reference clock used in a quasi-integer-ratio DFC scheme. This analysis allows us to stablish the limits on the number of comb lines (i.e., on the number of available independent sensing points) for a particular reference clock. By using a rubidium atomic clock (with a relative frequency stability of ∼10⁻¹³), we demonstrate up to 10⁵ sensing points along 2 km of fiber with tens of Hz sensing bandwidth.

Quadratic phase coding for SNR improvement in time-expanded phase-sensitive OTDR

Miguel Soriano-Amat, Hugo F. Martins, Vicente Durán, Sonia Martin-Lopez, Miguel Gonzalez-Herraez, and María R. Fernández-Ruiz
Opt. Lett. 46(17) 4406-4409 (2021)

Time-expanded φOTDR using low-frequency electronics

Miguel Soriano-Amat, Hugo F. Martins, Sonia Martin-Lopez, Miguel Gonzalez-Herraez, María R. Fernández-Ruiz, and Vicente Durán
Opt. Express 31(2) 843- 852 (2023)

Compensating for influence of laser-frequency-drift in phase-sensitive OTDR with twice differential method

Quan Yuan, Feng Wang, Tao Liu, Yu Liu, Yixin Zhang, Zhen Zhong, and Xuping Zhang
Opt. Express 27(3) 3664-3671 (2019)

Coherent dual-comb interferometry with quasi-integer-ratio repetition rates

Nicolas Bourbeau Hébert, Sylvain Boudreau, Jérôme Genest, and Jean-Daniel Deschênes
Opt. Express 22(23) 29152-29160 (2014)

Dynamic curvature sensing using time expanded ΦOTDR

Camilo Escobar-Vera, Miguel Soriano-Amat, Hugo F. Martins, David Barrera, Sonia Martin-Lopez, Miguel Gonzalez-Herraez, and María R. Fernández-Ruiz
Opt. Lett. 48(16) 4336-4339 (2023)