Sensitivity Enhancement of Fiber-Optic Accelerometers Based on the Weak Fiber Bragg Grating Array by Inscribing in Thin-Cladding Fiber

In this paper, we propose and demonstrate a method for enhancing the sensitivity of accelerometers using a thin-cladding weak fiber Bragg grating (WFBG) array. Compared to a 125 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\mu \mathrm{m}$</tex-math></inline-formula> cladding diameter single-mode fiber (SMF), a thin-cladding fiber (TCF) will produce greater deformation for the same force, resulting in a significant increase in the phase change of the transmitted light. The enhanced sensitivity was verified using a 60 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\mu \mathrm{m}$</tex-math></inline-formula> diameter SMF in a spring-mass accelerometer structure. The accelerometer has an operating bandwidth of 10 Hz to 400 Hz and a sensitivity of 284.96 rd/g (49.09 dB, ref rad/g), which represents a 9.92 dB increase in sensitivity compared to a 125 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\mu \mathrm{m}$</tex-math></inline-formula> diameter SMF with a sensitivity of 90.87 rd/g (39.17 dB). The proposed sensitivity enhancement scheme is applicable to almost all interferometric fiber optic accelerometers and offers significant advantages in large-scale quasi-distributed oil and gas exploration and monitoring.