Temperature-Compensated Optical Fiber Sensor for Dual-Parameter Measurement of Vector Magnetic Field and Temperature Based on Magnetic Fluid

In this paper, a temperature compensated optical fiber vector magnetic field and temperature dual-parameter sensor based on multimode intermodal interference (MMI) is proposed and experimentally demonstrated. The sensor head is prepared by using magnetic fluid (MF) encapsulated single-mode fiber (SMF)-six-hole single-core fiber (SHSCF)-noncore fiber (NCF)-SMF structure. Wherein offset splicing between the lead in SMF and the SHSCF is adopted to obtain a noncircular symmetry structure and effectively excite higher-order modes. In addition, employing a segment of NCF to be sandwiched between the SHSCF and the lead-out SMF is further to generate richer higher-order modes. Experimental results revealed that the transmission spectrum intensity of the sensor was sensitive to magnetic field and temperature, and the transmission spectrum wavelength drift of the sensor was only sensitive to temperature. Thus, wavelength drift response to temperature and intensity response to temperature can be employed to monitor temperature and to compensate magnetic field, respectively. In our experiments, magnetic field intensity sensitivity, direction sensitivity and temperature sensitivity of the proposed fiber sensor were 1.34 dB/mT, 0.23 dB/°, and 2.31 nm/°C, respectively. Additionally, transmission intensity response to temperature of 0.27 dB/°C is served as the temperature-compensation for magnetic field. The proposed fiber sensor has the advantages of compact structure, easy fabrication, high sensitivity and provides a novel sensing scenario for dual-parameter simultaneous measurement of magnetic field and temperature.