Coreless Optical Fiber Sensor Based on Surface Plasmon Resonance for Simultaneous Measurement of Magnetic Field and Temperature

A dual-parameter sensor based on a coreless optical fiber (CF) is designed for the simultaneous detection of magnetic fields (<italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">H</i>) and temperature (T). The side of the coreless optical fiber is polished to form a double D-shape and etched to a certain grove depth on the side surface for gold plating and filling with the magnetic fluid (MF) and polydimethylsiloxane (PDMS). The sensor operates on the principle of surface plasmon resonance (SPR) to achieve magnetic field and temperature sensing. Finite element analysis reveals the modal characteristics of the sensor, showing that the effective magnetic field and temperature detection ranges are 31 to 200 Oe and 20 to 80 °C, respectively. The maximum magnetic field sensitivity and temperature sensitivities are 20.207 nm/Oe and -8.423 nm/°C, respectively. Compared to other dual-parameter magnetic field and temperature sensors currently proposed, the magnetic field sensitivity increases by nearly two orders of magnitude, and the temperature sensitivity increases several times. The structure of photonic crystal fiber or anti-resonant fiber is complex. In contrast, this design offers a simpler structure and fabrication process. The sensor has immense potential in medical diagnosis, environmental detection, and aerospace fields.