Brillouin-Scattering Induced Noise in DAS: A Case Study

Boris G Gorshkov; Denis E Simikin; Alexey E Alekseev; Mikhail A Taranov; Konstantin M Zhukov; Vladimir T Potapov

doi:10.3390/s23125402

Brillouin-Scattering Induced Noise in DAS: A Case Study

Sensors (Basel). 2023 Jun 7;23(12):5402. doi: 10.3390/s23125402.

Authors

Boris G Gorshkov^{1

2}, Denis E Simikin^{2

3}, Alexey E Alekseev³, Mikhail A Taranov^{2

3}, Konstantin M Zhukov², Vladimir T Potapov³

Affiliations

¹ Prokhorov General Physics Institute of the Russian Academy of Sciences, Vavilov Street 38, 119991 Moscow, Russia.
² Petrofiber, LLC, Klinsky Proezd 7, 301664 Novomoskovsk, Russia.
³ Kotelnikov Institute of Radio-Engineering and Electronics, Fryazino Branch, Russian Academy of Sciences, Vvedenskogo Square 1, 141190 Fryazino, Russia.

Abstract

In the paper, the effect of spontaneous Brillouin scattering (SpBS) is analyzed as a noise source in distributed acoustic sensors (DAS). The intensity of the SpBS wave fluctuates over time, and these fluctuations increase the noise power in DAS. Based on experimental data, the probability density function (PDF) of the spectrally selected SpBS Stokes wave intensity is negative exponential, which corresponds to the known theoretical conception. Based on this statement, an estimation of the average noise power induced by the SpBS wave is given. This noise power equals the square of the average power of the SpBS Stokes wave, which in turn is approximately 18 dB lower than the Rayleigh backscattering power. The noise composition in DAS is determined for two configurations, the first for the initial backscattering spectrum and the second for the spectrum in which the SpBS Stokes and anti-Stokes waves are rejected. It is established that in the analyzed particular case, the SpBS noise power is dominant and exceeds the powers of the thermal, shot, and phase noises in DAS. Accordingly, by rejecting the SpBS waves at the photodetector input, it is possible to reduce the noise power in DAS. In our case, this rejection is carried out by an asymmetric Mach-Zehnder interferometer (MZI). The rejection of the SpBS wave is most relevant for broadband photodetectors, which are associated with the use of short probing pulses to achieve short gauge lengths in DAS.

Keywords: distributed acoustic sensing (DAS); fiber optic sensors; phase-sensitive optical time-domain reflectometer (phase-OTDR); spontaneous Brillouin scattering (SpBS); stimulated Brillouin scattering (SBS).

MeSH terms

Fertilization*
Heart Rate
Likelihood Functions

Grants and funding

The current work was performed partially as a State task. This work was partially supported by Petrofiber, LLC. Different aspects of the work were partially supported by the grants of Russian Science Foundation No. 21-12-00407 (development of sensing methods).