An Optical Fiber-Based Surface Plasmon Resonance Sensor for Simultaneous Measurement of Temperature and Magnetic Field Intensity

In this article, a surface plasmon resonance (SPR) sensor was designed based on the no-core optical fiber (NCF) for the simultaneous measurement of magnetic field intensity and ambient temperature. The sensor structure was mainly comprised of two NCF segments spliced between two multimode optical fibers, and different metal films were deposited on the NCF surface to generate the SPR effect: the NCF coated by silver and wrapped by MF was used for magnetic field sensing and the NCF coated by gold and wrapped by PDMS was used for temperature sensing. The proposed sensor successfully avoided the influence of temperature on magnetic field sensing, and vice verse. Detailed experimental investigation showed that in the magnetic field intensity range of 0–248 Gs, a maximum sensitivity of 132 pm/Gs was obtained with good linearity (coefficient of determination 0.991), and in the temperature range of 20 °C–60 °C, the corresponding sensitivity was −1.960 nm/°C with a linearity higher than 0.997. The proposed sensor can perform an accurate sensing even in weak magnetic field environment and simultaneously provide information about temperature variation. Being simple in structure, easy to manufacture and stable in performance, this sensor provides a feasible solution for the integration and miniaturization of multi-parameter measurement.