Abstract
A magnetic field sensor is proposed by placing a dual-polarization fiber grating laser under a copper wire. With a perpendicular magnetic field applied, an electrical current flowing through the copper wire can generate Ampere force to squeeze the fiber grating laser, resulting in the birefringence change inside the laser cavity and hence the change of the beat note frequency. When an alternating current is injected into the copper wire, the magnetic field induced beat note frequency change can be discriminated from environment disturbances. A novel fiber-optic magnetic field sensor is therefore demonstrated with high sensitivity and inherent immunity to disturbances.
Highlights
Fiber-optic magnetic field sensors have been actively studied over years because of the advantages over their electronic counterparts in immunity to electromagnetic interference, light weight, compact size and large bandwidth
The proposed fiber-optic magnetic field sensor was put in a perpendicular magnetic field generated by two permanent magnets with their spacing varied to tune the magnetic field magnitude
The fiber grating laser was a dual-polarization distributed Bragg reflector (DBR) fiber laser inscribed on an Er-doped fiber (Fibercore M-12) with grating lengths of 7.5 mm and 5.5 mm, respectively, and a grating spacing of 6 mm
Summary
Fiber-optic magnetic field sensors have been actively studied over years because of the advantages over their electronic counterparts in immunity to electromagnetic interference, light weight, compact size and large bandwidth. Schemes based on other mechanisms normally measure magnetic fields indirectly and need external transducers which usually enhance their sensitivities. Such external transducers may result in some disadvantages. Dual-polarization fiber grating laser based sensors exhibit high sensitivities and much easier and simpler signal extraction by electronic signalprocessing. We propose a novel magnetic field sensor based on dual-polarization fiber grating lasers and magnetic field induced Ampere force. The Ampere force is generated by an electric current in a perpendicular magnetic field, which presses the dual-polarization fiber grating laser to shift the beat signal frequency. We demonstrate when an alternating electric current is employed, the proposed scheme can discriminate the magnetic field from environment disturbance very well, showing an inherent ability of anti-disturbance
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