Comparative study of lab-on-fiber vector magnetic field sensor based on multimode and few-mode fiber

A kind of reflective vector magnetic field sensor with wedge-shaped fiber tip based on surface plasmon resonance (SPR) and magnetic fluid (MF) has been fabricated and investigated. Multimode fiber (MMF) and few-mode fiber (FMF) were grinded and polished to get the wedge-shaped fiber tip, which was then plated with nanoscale gold film for exciting SPR. The as-fabricated tip was immersed in MF, which was used as the magnetic field sensitive material. Experimental results show that the magnetic field intensity and direction sensitivities of the magnetic field sensors based on MMF and FMF are 2317 pm/mT, 497 pm/° and 6776 pm/mT, 2313 pm/° respectively, which proves that the proposed sensor based on wedge-shaped fiber tip has great potential for realizing lab-on-fiber devices and applications.