Intensity-based magnetic field measurement employing tilted long-period fiber gratings

Abstract

An intensity-interrogated fiber magnetic field sensor based on magnetic fluid (MF) and tilted long-period fiber grating (TLPFG) has been proposed. The sensor is constructed by a TLPFG immersed in the MF. The TLPFGs supported the coupling between the LP01 core mode and the forward-propagating cladding modes with different azimuthal order l = 0, 1, 2,…, which shows different spectral response behaviors with normal long-period fiber gratings. The experimental results and theoretical analysis show that resonance wavelengths of TLPFG present different characteristics by tuning the applied magnetic field intensity. The transmission loss of the TLPFG increases for some dips, while they reduce for the others with the increment of the applied magnetic field intensity. Taking advantage of the optical power difference for various wavelength regions, a magnetic field intensity sensitivity of 0.05 dB Oe−1 could be achieved for a magnetic intensity range from 75 Oe to 300 Oe. Due to its low cost and compactness, the proposed sensor is expected to find potential applications in the field of magnetic field measurement and photonic devices.