Sensitivity enhanced magnetic field sensor based on Farady effect and dual-polarization fiber grating laser

Abstract

A silicon steel sheet is proposed in this paper to work as a magnetic field concentrator to enhance the sensitivity of a Faraday effect based magnetic field sensor using a dual-polarization fiber grating laser. When the silicon steel sheet is placed close to the cavity of the fiber grating laser, the magnetic field is concentrated around the silicon steel sheet and hence the fiber grating laser experience stronger magnetic field than the case without the silicon steel sheet, which results in a larger magnetic field induced beat note frequency change after photodetection of the two orthogonally polarized laser outputs. With the same axial magnetic field, the experiment results confirm that the sensitivity of the sensor with a silicon steel sheet is improved over the one without a silicon steel sheet, which validates our proposal.