The Impact of Rayleigh Scattering in UWFBG Array-Based Φ-OTDR and Its Suppression Method

Feng Wang; Yong Yu; Rui Hong; Ruifeng Tian; Yixin Zhang; Xuping Zhang

doi:10.3390/s23115063

The Impact of Rayleigh Scattering in UWFBG Array-Based Φ-OTDR and Its Suppression Method

Sensors (Basel). 2023 May 25;23(11):5063. doi: 10.3390/s23115063.

Authors

Feng Wang¹, Yong Yu¹, Rui Hong¹, Ruifeng Tian¹, Yixin Zhang^{1

2}, Xuping Zhang^{1

2}

Affiliations

¹ Key Laboratory of Intelligent Optical Sensing and Manipulation, Ministry of Education, College of Engineering and Applied Sciences, Nanjing University, Nanjing 210093, China.
² Shenzhen Research Institute of Nanjing University, Shenzhen 518000, China.

Abstract

Ultra-weak fiber Bragg grating (UWFBG) array-based phase-sensitive optical time-domain reflectometry (Φ-OTDR) utilizes the interference interaction between the reference light and the reflected light from the broadband gratings for sensing. It significantly improves the performance of the distributed acoustic sensing system (DAS) because the intensity of the reflected signal is much higher than that of the Rayleigh backscattering. This paper shows that Rayleigh backscattering (RBS) has become one of the primary noise sources in the UWFBG array-based Φ-OTDR system. We reveal the impact of the Rayleigh backscattering signal on the intensity of the reflective signal and the precision of the demodulated signal, and we suggest reducing the pulse duration to improve the demodulation accuracy. Experimental results demonstrate that using light with a 100 ns pulse duration can improve the measurement precision by three times compared with the use of a 300 ns pulse duration.

Keywords: Rayleigh backscattering (RBS); demodulation accuracy; distributed acoustic sensing system (DAS); ultra-weak fiber Bragg grating (UWFBG); Φ-OTDR.

MeSH terms

Acoustics*
Computer Communication Networks
Heart Rate
Optical Devices*

Grants and funding

This research was funded by the National Natural Science Foundation of China (61975076, 62175100, U2001601) and the Qing Lan Project of Jiangsu Province.