Torsion sensor based on tilted few-mode optical fiber grating

Abstract

The present invention discloses a torsion sensor based on tilted few-mode optical fiber grating, which comprises a broadband light source, a polarizer, a polarization controller, an optical fiber fixing clip, a tilted few-mode optical fiber grating, a optical fiber rotator and a spectrometer, wherein the polarization controller is connected to the optical fiber rotator through the tilted few-mode optical fiber grating; the optical fiber rotator is connected to the spectrometer through the few-mode optical fiber. The optical signal emitted by the broadband light source is transmitted to the polarizer through a single-mode optical fiber to obtain linearly polarized light; the polarization controller is utilized to change the polarization state of the linearly polarized light; and the optical fiber rotator is rotated to make the tilted few-mode optical fiber grating twisted. The tilted few-mode optical fiber grating is excited to a high-order mode and is then transmitted to the spectrometer through the few-mode optical fiber; and the transmission spectrum of the tilted few-mode optical fiber grating is obtained by the spectrometer. The sensor of the invention can utilize the characteristics that the polarization state of the high-order mode of a few-mode optical fiber changes with the torsion of the optical fiber to realize the sensing of the optical fiber torsion by the transmission spectrum of the tilted few-mode optical fiber grating and has higher sensitivity.

Description

technical field [0001] The invention relates to a torsion sensor based on an inclined few-mode fiber grating, belonging to the technical field of fiber grating sensors. Background technique [0002] Because of its ability to excite the cladding mode and enhance the interaction between the fiber and the outside world, tilted fiber gratings have always attracted people's attention, and have been widely used in the measurement of external environmental factors such as temperature, stress, and refractive index. In order to improve the sensitivity of tilted fiber gratings, commonly used methods include coating thin-film media on the outside of the fiber, and using long-period gratings and other structures. However, ordinary tilted fiber gratings are not very sensitive to fiber torsion. In order to realize the sensing and measurement of torsion, Dawei Yu et al. used the few-mode optical fiber with elliptical core as the sensing of torsion. However, how to better measure the twis...

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Problems solved by technology

[0004] The technical problem to be solved by the present invention is to overcome the deficiencies of the prior art and provide a torsion sensor based on a tilted few-mode fiber grating. The fiber grating torsion sensor before the solution has low sensitivity, and the signal is prone to attenuation during work. As a result, it is impossible to accurately measure the twist angle of the fiber by using the change of the transmission spectrum

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