Laser & Optoelectronics Progress, Volume. 60, Issue 7, 0706009(2023)
Ultrasensitive Methane Volume Fraction Sensor Based on Long Period Fiber Grating and Back-Propagation Neural Network
An ultrasensitive long period fiber grating (LPFG) sensor is proposed and investigated for the measurement of methane volume fraction by applying the selective adsorption property of cryptophane-E to methane. The cladding diameter is reduced to make the low order cladding mode LP06 work near dispersion turning point (DTP). The TiO2 thin film with optimized thickness is coated on the surface to ensure coupled cladding mode LP06 within the mode transition (MT) region, which can result in higher refractive index (RI) sensitivity of LPFG. The methane gas changes the RI of the cryptophane-E that is coated on the surface of the LPFG sensor, and then the methane volume fraction can be measured by monitoring the shift of the resonance wavelength. A high sensitivity of 249.6 nm/% can be achieved when the methane volume fraction changes from 0% to 3.5% owing to the contribution of DTP and MT. A back-propagation (BP) neural network is designed for the nonlinearity response of the sensor at different volume fraction. The result shows that a maximum predicted error of 0.008% is recorded in the methane volume fraction change range. The excellent performance shows that the proposed sensor has potential application value in the field of coal mine safety monitoring.
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Chao Du, Bin Zhang, Shuang Zhao, Qiuyu Wang, Li Zhang, Liqin Cui, Xiao Deng. Ultrasensitive Methane Volume Fraction Sensor Based on Long Period Fiber Grating and Back-Propagation Neural Network[J]. Laser & Optoelectronics Progress, 2023, 60(7): 0706009
Category: Fiber Optics and Optical Communications
Received: Oct. 10, 2022
Accepted: Nov. 30, 2022
Published Online: Mar. 31, 2023
The Author Email: Du Chao (duchao@tyut.edu.cn), Deng Xiao (dengxiao@tyut.edu.cn)