Distributed Acoustic Sensor Using a Double Sagnac Interferometer Based on Wavelength Division Multiplexing

• Main Authors: Chernutsky, A.O (Author), Choban, T.V (Author), Karasik, V.E (Author), Koshelev, K.I (Author), Pnev, A.B (Author), Stepanov, K.V (Author), Zhirnov, A.A (Author)
• Format: Article
• Language: English
• Published: MDPI 2022
• Subjects: A.Fibres; Acoustic devices; Acoustic Sensors; Data handling; disturbance localization; Disturbance localization; fiber optic sensor; Fiber optic sensors; Fiber optics; Fiber-optics; Fibers; Fibre-optic sensor; Interferometers; Sagnac interferometer; sensitivity; Sensitivity; Signal formation; Signals analysis; Two wavelength
• Online Access: View Fulltext in Publisher

 We demonstrated a fiber optic distributed acoustic sensor based on a double Sagnac interferometer, using two wavelengths separated by CWDM modules. A mathematical model of signal formation principle, based on a shift in two signals analysis, was described and substantiated mathematically. The dependence of the sensor sensitivity on a disturbance coordinate and frequency was found and simulated, and helped determine a low sensitivity zone length and provided sensor scheme optimization. A data processing algorithm without filtering, appropriate even in case of a high system noise level, was described. An experimental study of the distributed fiber optic sensor based on a Sagnac interferometer with two wavelengths divided countering loops was carried out. An accuracy of 24 m was achieved for 25.4 km SMF sensing fiber without phase unwrapping. © 2022 by the authors. Licensee MDPI, Basel, Switzerland.