Phase Shift Fiber Loop Ring-Down Cavity Integrated SNS Structure for Magnetic Field Sensing

This letter proposes a new magnetic field sensor using phase-shift fiber loop ring-down (PS-FLRD) technique combined with single mode-no core-single mode fiber (SNS) structure. This is the first time the PS-FLRD technique has been applied to magnetic field sensing. The magnetic fluid (MF) coated SNS structure is the sensing head. Among them, we have creatively proposed and derived the discrete PS-FLRD model. We calculated and experimentally verified the linear region of the system and achieved
$R^{2}$
above 0.999. Finally, we have used the linear region in combination with the SNS structure to measure the magnetic field, achieving a sensitivity of
${5\times 10}^{-5}$
/Gs in the measurement range of 0-200Gs. This work demonstrates the significant potential of the PS-FLRD technique combined with interferometric structures in sensing.