Sensitivity-Enhanced Strain Sensor With a Wide Dynamic Range Based on a Novel Long-Period Fiber Grating
Xudong Chen, Wenhuan Chen, Yue Liu, Shijie Liu, Shuo Zhang, Qi Yan, Weimin Sun, Tao Geng
Abstract
A long period fiber grating prepared by multimode fibers (MMF-LPFG) is proposed and experimentally demonstrated as a sensitivity-enhanced strain sensor. The core diameter mismatch between the MMFs excites the high order cladding mode to obtain a compact sensing structure (3.6 mm). The strain sensitivity of the MMF-LPFG structure is enhanced to −15.06 pm/ <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\mu \varepsilon $ </tex-math></inline-formula> when the grating period is closer to the dispersion turning point (DTP). Meanwhile, the novel fiber structure also has an excellent mechanical property to achieve a large dynamic range ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\text{0-4508} ~\mu \varepsilon $ </tex-math></inline-formula> ) in strain measurement.