Highly Sensitive Magnetic Field Sensors Based on a D-Type Fiber With Bi₂O₂ Se Film

In this article, we propose a magnetic field sensor based on a multimode-D-type-multimode (MMF-D-type-MMF) fiber structure employing surface plasmon resonance (SPR). The sensor’s surface is coated with a layer composed of indium tin oxide (ITO), silver (Ag), and a 2-D material known as Bi2O2Se. Bi2O2Se exhibits varying magnetic permeability within a specific magnetic field strength range, a characteristic confirmed in practical tests. To enhance the sensor’s sensitivity to magnetic fields, we implemented several optimization measures. These measures encompassed adjustments to: 1) the concentration of the magnetic fluid (MF); 2) the thickness of the Bi2O2Se layer; and 3) the selection of fiber type. We conducted simulations and experimental tests to refine these parameters. Consequently, the proposed D-type sensor demonstrates a sensitivity of 0.4325 nm/GS within the 40–150 GS magnetic field strength range, representing a significant 75.31% sensitivity improvement achieved through the aforementioned enhancement measures. When compared to other fiber-optic magnetic field sensors, our proposed sensor stands out for its exceptional sensitivity, straightforward design, robust repeatability, strong anti-interference capabilities, and high stability. As a result, it holds significant potential for a wide range of applications in aerospace, aviation, environmental monitoring, and related fields. The sensor has a high sensitivity in the range of 40–150 GS, which can monitor the magnetic field strength in life in real time and determine whether it meets the human body safety magnetic field standard.