Fiber Bragg grating (FBG) array,consisting of a number of sensing units in a single optical fiber,can be practically applied in quasi-distributed sensing networks.Serious signal crosstalk occurring between large-serial of identical FBGs,however,has limited the further increase in the number of sensing units,thus restricting applications only for short-distance sensing networks.To reduce the signal crosstalk,we design two novel types of 10-kilometer-long FBG arrays with 10000 equally spaced gratings,written on-line using a customized grating inscription system,which is affiliated to a drawing tower.Main factors causing signal crosstalk,such as spectral shadowing and multiple reflections,are firstly investigated in theory.Consistent with the theoretical findings,experimental results are proving that ultra-weak (the reflectivity of～-40dB) and multi-wavelength gratings of a number more than 10000 can be readily identified,with satisfied low crosstalk.The maximum attenuation of grating signal and minimum signal-to-noise ratio (SNR) in a single-wavelength array are 10.69dB and 5.62dB,respectively.As a comparison,by increasing the number of central wavelengths to three,the attenuation can be effectively reduced to 5.54dB and the minimum SNR has been improved to 8.14 dB.The current study significantly enhances the multiplexing capacity of FBG arrays and demonstrates promising potentials for establishing large-capacity quasi-distributed sensing networks.

Wenjing GAO;Jianxia LIU;Huiyong GUO;Xin JIANG;Shaofa SUN;Haihu YU

Hubei Key Laboratory of Radiation Chemistry and Functional Materials,Hubei University of Science and Technology,Xianning 437100,China;National Engineering Laboratory for Fiber Optic Sensing Technology,Wuhan University of Technology,Wuhan 430070,China

光子传感器（英文版）

[1]Wenjing GAO;Jianxia LIU;Huiyong GUO;Xin JIANG;Shaofa SUN;Haihu YU-.Multi-Wavelength Ultra-Weak Fiber Bragg Grating Arrays for Long-Distance Quasi-Distributed Sensing)[J].光子传感器（英文版）,2022(02):185-195

69dB,62dB,54dB

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