Enhanced Magnetic Field Sensing Using a Magnetic Graphene Oxide-Coated Tapered Fiber Optic Sensor

In this work, we have developed a portable fiber-optic sensor characterized by its robust immunity to electromagnetic interference (EMI), exceptional sensitivity, and real-time monitoring capabilities for magnetic fields. This sensor exhibits remarkable accuracy and stability in measuring both increasing and decreasing magnetic fields. To enhance the sensor's performance, we designed, simulated, and fabricated a tapered fiber structure with a tapered diameter of $40 ~\mu \text{m}$ using a combiner manufacturing system (CMS). Additionally, we employed a 2-D material known as magnetic graphene oxide (MGO) to immobilize the sensing region of the tapered fiber optic sensor. The key principle behind this sensor lies in the refractive index (RI) changes of MGO when subjected to a magnetic field, leading to a wavelength shift in the transmitted spectrum. Through rigorous experimentation, we thoroughly assessed the measurement range, sensitivity, and accuracy of the sensor in detecting both increasing and decreasing magnetic fields. Consequently, we determined the sensitivity of the fiber optic magnetic field sensor to be 0.9 and 1.6 pm/mT for increasing and decreasing magnetic fields in the wide measurement range of 5–600 mT, respectively. This sensor holds significant promise in various applications, including medical testing and scientific measurements, owing to its exceptional accuracy, compact size, and noninvasive measurement capabilities. Furthermore, its stability and noncontact measurement feature position it as a valuable tool in controlled nuclear fusion, space exploration, and geophysical research.