A multi-directional magnetic field sensor based on tapered few mode fiber and magnetic fluid

A multi-directional magnetic field sensor based on tapered few mode fiber and magnetic fluid is proposed via a single mode fiber (SMF)-tapered few mode fiber (TFMF)-SMF structure. Magnetic fluid (MF) is encapsulated outside the TFMF to detect magnetic fields in different directions. The experimental results show that the change trend of the transmission spectrum is related to the direction of the magnetic field, independent of the length of the taper. When a vertical magnetic field is applied to the sensor, the transmission spectrum is red-shifted with the decrease of the magnetic field intensity. When a parallel magnetic field is applied to the sensor, the transmission spectrum is blue-shifted with the decrease of the magnetic field intensity. For the same sensor, the magnetic field sensitivity in vertical direction is significantly higher than that in parallel direction, and can be up to 70,792.85 pm/Oe by applying a magnetic field direction of 180 degrees. The sensor has the advantages of simple fabrication and high sensitivity, and has a good application prospect in scientific research and other magnetic field measurement.