Optic fiber magnetic field sensor based on the miniature pull-taper twin-core photonic crystal fiber

Abstract

In this paper, a optical fiber magnetic field sensor with the tapered twin-core photonic crystal fiber coupling structure has been presented and experimentally demonstrated. The magnetic fluid(MF) was injected into the air hole between two parallel fiber cores of the photonic crystal fiber, and then the two fiber cores of the twin-core photonic crystal fiber infiltrated with MF were tapered horizontally. A total reflection film was plated on the end face of the fusion cone of the twin-core photonic crystal fiber. The guided light was transmitted from the input port to the pull-cone area of the fiber, reflected by the reflection end face after mode coupling, and finally reflected from the output port to the output fiber. According to the above light transmission mode of reflective fiber coupler, The magnetic field measurement principle was studied, which the coupling region of twin-core photonic crystal fiber had been injected MF. The change of the effective refractive index will lead to the central wavelength shift of the fiber magnetic field coupler, and the magnetic field is measured by inquiring the wavelength shift of the transmission spectrum. The magnetic field response characteristics of the sensor were studied and analyzed through experiments. The experimental results show that the sensitivity of this method can reach 116pm/Oe. The fiber magnetic field sensor has the advantages of miniaturization, high sensitivity, and no electromagnetic interference. The magnetic field sensor can be widely used in the field of aviation, military, transportation, medicine and other fields of magnetic field accurate measurement.