Acta Optica Sinica, Volume. 41, Issue 13, 1306014(2021)
Distributed Vibration Sensing System with High Signal-to-Noise Ratio Based on Ultra-Weak Fiber Bragg Grating
A distributed vibration sensing system with a high signal-to-noise ratio (SNR) based on an ultra-weak fiber Bragg grating is proposed in this paper. The system uses an online inscribed chirped grating array with a 3 dB bandwidth greater than 3.4 nm and a reflectivity of 10 -5 as the sensing fiber, and phase demodulation is realized through typical dual-pulse modulation and a 3×3 coupler. To eliminate interference noises from optical components including laser, modulator, and optical amplifiers, we employ the least mean square algorithm and a symmetric detection structure for adaptive filtering. The experimental results show that compared with the wavelet denoising method, the method can greatly decrease the system noise. It can reduce the high-frequency noise floor of the 1 kHz demodulated signal by 40.1 dB at the maximum, and the SNR is as high as 96.5 dB. For the 2 km long sensing fiber, the strain sensitivity of the system reaches 13.66 pε/√Hz at 1-5 kHz.
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Jianguan Tang, Yuzhe Liu, Chengli Li, Huiyong Guo, Minghong Yang. Distributed Vibration Sensing System with High Signal-to-Noise Ratio Based on Ultra-Weak Fiber Bragg Grating[J]. Acta Optica Sinica, 2021, 41(13): 1306014
Category: Fiber Optics and Optical Communications
Received: Mar. 17, 2021
Accepted: Apr. 29, 2021
Published Online: Jul. 11, 2021
The Author Email: Yang Minghong (minghong.yang@whut.edu.cn)