An All-Optical Vector Magnetic Field Sensor Based on Magnetic Fluid and Side-Polished Hollow-Core Optical Fiber

We demonstrate an optical fiber vector magnetic field sensor based on Mach-Zehnder interferometer by splicing a section of side-polished hollow-core fiber between two sections of single-mode fiber. As a varied magnetic field is applied to the magnetic fluid encapsulated sandwiched structure, the transmission spectra of the sensor will vary with the intensity and the direction of the magnetic field. In our experiments, at the incident light wavelength around 1510 nm, the magnetic field orientation sensitivity and intensity sensitivity are 180 pm/° and 240 pm/mT, respectively. In addition, a high contrast of about 20 dB between the signal interference dip with the noise interference dip is obtained in our experiments. The proposed all-optical fiber magnetic field sensor has the advantages of simple structure, compact size, low cost and easy fabrication.