Temperature Compensated Magnetic Field Sensor Using Magnetic Fluid Filled Exposed Core Microstructure Fiber

A temperature compensated magnetic field sensor using magnetic fluid (MF) filled exposed core fiber (ECF) has been proposed to detect magnetic field strength and temperature (MFT) simultaneously in this article. The designed sensor was formed by splicing an ECF between two sections of single-mode fibers (SMFs), in which the ECF’s exposed side was filled with MF. ECF is a multimode fiber that supports multiple modes of light transmitting and produces mode interference in the core. Different order modes of light excited in the ECF have individual sensitivities to MFT. Therefore, interference spectra of two different pair modes can be monitored to measure MFT simultaneously. The results show that the sensor responds well to MFT. The maximum MFT sensitivities are −0.18 nm/mT and −0.16 nm/lpzrptcircC. The limit of detections (LOD) of MFT is 1.7 mT and 1.9 lpzrptcircC. The sensor is particularly suitable for simultaneous detection of MFT in narrow spaces, such as industrial flaw detection, aerospace, and medical applications.

I. Introduction

Magnetic fields are significant in medical, military, construction, aerospace, power systems, and other fields. Therefore, research on magnetic field sensors has become a hotspot in last several years [1], [2]. Fiber-optic sensors have several advantages in magnetic field detection on account of their characteristics of anticorrosion, high sensitivity, long-distance transmission, and multiplex. So far, fiber-optic magnetic field strength sensors can be categorized into many varieties. For example, they can combine with magneto-optical effects [3], the Joule effect [4], and magnetic fluid (MF) [5], [6]. The sensors based on the magneto-optical effect [7] and the Joule effect [8] have high resolution and wide magnetic field strength measurement ranges, but they have poor signal stabilities [9].