Highly Sensitive Reflective Fabry-Perot Magnetic Field Sensor Using Magnetic Fluid Based on Vernier Effect

• Published in: IEEE transactions on instrumentation and measurement Vol. 70; pp. 1 - 8
• Main Authors: Zhao, Yong, Wang, Xi-Xin, Lv, Ri-Qing, Li, Gui-Lin, Zheng, Hong-Kun, Zhou, Yi-Fan
• Format: Journal Article
• Language: English
• Published: New York IEEE 2021; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Capillarity; Capillary tubes; Cavity resonators; Concave surface; Electron tubes; Fabry–Perot (FP); Glass; Jupiter; Linearity; magnetic field sensor; Magnetic fields; magnetic fluid (MF); Magnetic fluids; Magnetic liquids; Reflection; Refractivity; Sensitivity; Sensors; Splicing; Vernier effect; Wave reflection
• ISSN: 0018-9456; 1557-9662
• DOI: 10.1109/TIM.2020.3017245

A highly sensitive reflective Fabry-Perot (FP) magnetic field sensor using magnetic fluid (MF) based on the Vernier effect is presented and experimentally verified. Capillary action acts as an injection of MF into an FP cavity, which is composed of a single-mode fiber (SMF), capillary glass tube, and a short section of SMF coated with gold film. Vernier effect is formed by the MF cavity and air cavity in the FP magnetic field sensor, where the surface of MF is concave. The refractive index (RI) of MF depends on the magnetic field, and therefore, the wavelength of the reflection spectrum of the fabricated sensor can be sensitive to the magnetic field. The magnetic field sensor's sensitivity is up to 1.02602 nm/Gs from 118.768 to 166.261 Gs, and the resolution is 0.0078 Gs. The sensor shows good linearity within the range of 71.317-231.751 Gs, and the linearity is larger than 0.999. In this article, a new type FP cavity fabricated by splicing SMF inside the capillary glass tube is proposed, and MF can be injected into the FP cavity, which can also be applied to other liquids to generate Vernier effect. The concave surface of MF is creatively applied to the sensors, and the experimental verification is carried out in a capillary glass tube, which provides a basis on the capillary action of other fluids in fiber sensing.