Use of the polarization properties of magneto-optic fiber Bragg gratings for magnetic field sensing purposes

The transmission and polarization properties of magneto-optic fiber Bragg gratings (MFBGs) with Faraday Effect are studied in this paper. The evolutions of transmission spectrum for different input state of polarizations (SOPs) are simulated with Jones Matrix method. It is demonstrated that the monitoring of the polarization-dependent loss (PDL) maximum values provide a new magnetic field measurement. Furthermore the influences of transmission spectrum on the characteristics of MFBG sensors are analyzed. It is shown that the sensitivity and measurement range depend on the slope and bandwidth of the transmission spectrum, respectively. Moreover the MFBG structure with triangular-shaped transmission spectrum is designed for dynamic magnetic field sensing. The simulation shows that the maximal amplitude of the PDL varies linearly in the magnetic field range of 0–114.2 mT with a slope of 0.091 dB/mT. A multi-section MFBG structure is also proposed for distributed magnetic field sensing.

Research highlights
► We propose a new magnetic field sensing mechanism based on PDL of FBG.
► The characteristics of sensors depend on the parameters of transmission spectrum.
► Triangular-shaped FBG determine sensor properties directly by transmission spectrum.
► The proposed FBG structure is suitable for dynamic magnetic field sensing.