Magnetic Field Sensing by Magnetic-Fluid-Coated Capillary Long-Period Fiber Gratings

Abstract

In this paper, we presented and experimentally investigated a novel magnetic field sensor (MFS) based on magnetic fluid (MF)-coated capillary long-period fiber gratings (CLPFGs). The CLPFGs with short length of no more than 10 mm and period of 1 mm were fabricated by point-to-point arc discharge method and then infiltrated in an MF-filled glass tube forming a packaged MF-coated CLPFGs MFSs. A redshift in resonances of CLPFGs was brought out after packaging process, due to external refractive index changing. With the increasing external magnetic field, the intensity of resonant dips gradually decreased, which is caused by magnetostrictive effect together with refractive index variations. Moreover, CLPFGs with the same grating period and different grating lengths were comparatively investigated and analyzed. The resonant dips with larger transmissive depth present faster descend to the external magnetic field, resulting in higher sensitivity. The sensitivity of 0.036 dB/Oe could be obtained, when the CLPFGs have a grating length of 9 mm. What is more, the sensor is insensitive to temperature, which can avoid the effect of temperature. The proposed MF-coated CLPFGs MFS has potential applications in magnetic field systems.

Received: 22 September 2023 | Revised: 16 November 2023 | Accepted: 20 November 2023

Conflicts of Interest
Yunhe Zhao is an Associate Editor for Journal of Optics and Photonics Research, and was not involved in the editorial review or the decision to publish this article. The authors declare that they have no conflicts of interest to this work.

Data Availability Statement

Data are available from the corresponding author upon reasonable request.