A MMF-TSMF-MMF Structure Coated Magnetic Fluid for Magnetic Field Measurement

An optical fiber Mach-Zehnder interferometer (MZI) coated by magnetic fluid (MF) is fabricated for magnetic field measurement. The interferometer is composed of multimode fiber-taper single mode fiber-multimode fiber (MTSM). The two MMFs play the role of a beam splitter and a coupler. The TSMF induces the generation of high-order cladding mode and enhances the re-coupling ability of the interferometer. The transmission spectrum and cladding modes with different taper waist diameter are theoretically analyzed. Interference dips are sensitive to the alteration of magnetic field intensity when the taper waist diameter of interferometer is $34~\mu \text{m}$ . The highest sensitivity is up to −0.81 nm/mT at the magnetic field range of 8–17 mT.