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Frequency stability requirements in quasi-integer-ratio time-expanded phase-sensitive OTDR
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-φ OTDR 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. ; Comunidad de Madrid ; Ministerio de Ciencia e Innovación ; Agencia Estatal de Investigación ; Generalitat Valenciana ; Universitat Jaume I
Frequency stability requirements in quasi-integer-ratio time-expanded phase-sensitive OTDR
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-φ OTDR 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. ; Comunidad de Madrid ; Ministerio de Ciencia e Innovación ; Agencia Estatal de Investigación ; Generalitat Valenciana ; Universitat Jaume I
Frequency stability requirements in quasi-integer-ratio time-expanded phase-sensitive OTDR
Soriano Amat, Miguel (author) / Fidalgo Martins, Hugo (author) / Durán, Vicente (author) / Fermoso Santos, Pablo (author) / Martín López, Sonia (author) / González Herráez, Miguel (author) / Fernández Ruiz, María Del Rosario (author) / Ingeniería Fotónica / Universidad de Alcalá. Departamento de Electrónica
2022-10-27
777
Article (Journal)
Electronic Resource
English
Time-expanded phase-sensitive OTDR: High-resolution DAS based on dual-comb spectroscopy
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