The Sensitivity Improvement Characterization of Distributed Strain Sensors Due to Weak Fiber Bragg Gratings

Konstantin V Stepanov; Andrey A Zhirnov; Anton O Chernutsky; Kirill I Koshelev; Alexey B Pnev; Alexey I Lopunov; Oleg V Butov

doi:10.3390/s20226431

The Sensitivity Improvement Characterization of Distributed Strain Sensors Due to Weak Fiber Bragg Gratings

Sensors (Basel). 2020 Nov 11;20(22):6431. doi: 10.3390/s20226431.

Authors

Konstantin V Stepanov¹, Andrey A Zhirnov^{1

2}, Anton O Chernutsky¹, Kirill I Koshelev¹, Alexey B Pnev¹, Alexey I Lopunov², Oleg V Butov²

Affiliations

¹ Bauman Moscow State Technical University, 2-nd Baumanskaya 5-1, 105005 Moscow, Russia.
² Kotelnikov Institute of Radioengineering and Electronics of RAS, Mokhovaya 11-7, 125009 Moscow, Russia.

Abstract

Weak fiber Bragg gratings (WFBGs) in a phase-sensitive optical time-domain reflectometer (phi-OTDR) sensor offer opportunities to significantly improve the signal-to-noise ratio (SNR) and sensitivity of the device. Here, we demonstrate the process of the signal and noise components' formation in the device reflectograms for a Rayleigh scattering phi-OTDR and a WFBG-based OTDR. We theoretically calculated the increase in SNR when using the same optical and electrical components under the same external impacts for both setups. The obtained values are confirmed on experimental installations, demonstrating an improvement in the SNR by about 19 dB at frequencies of 20, 100, and 400 Hz. In this way, the minimum recorded impact (at the threshold SNR = 10) can be reduced from 100 nm per 20 m of fiber to less than 5 nm per 20 m of fiber sensor.

Keywords: distributed fiber optic sensor; phi-OTDR; weak fiber Bragg gratings.

Abstract

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