Resonantly enhanced Faraday rotation in a microcoil current sensor

Magnetic field sensor based on multi-port microcoil resonator

“…Spectra along larger wavelength ranges were recorded and are shown in figure 4(a). Unlike the small shift of the resonance wavelength associated to increasing magnetic fields, the variation in the intensity of the transmission spectra at different wavelengths for different magnetic field strengths can be clearly observed and it was ascribed to the strong polarization dependence of the Faraday effect in MMCRs [6,7]. In figure 4(a) the recorded power changes at the wavelengths 1 ( =1552.73 nm) and 2 ( =1552.837 nm) for different magnetic field strengths provide an alternative detection mechanism for magnetic field sensing.…”

“…The magnetic field causes a rotation in the polarization azimuth ( 0 ) of linearly polarized light which is proportional to the medium Verdet constant (V ) and the length of interaction. In a microcoil resonator, the Faraday rotation associated with a single turn is given by: [6,7] 0 (2 ) VB r…”

“…While silica exhibits an exceedingly small Verdet constant, in this sensing system the overall Faraday rotation is enhanced by the number of turns in the microfiber coupler coils and by the resonating effect of the coil which effectively increases the light optical path. The MMCR exhibits an extremely large polarization dependence: the two orthogonal polarizations have significantly different resonance spectra, both in terms of resonance wavelength and strength [6,7]. Thus, any changes in the azimuth of the light polarization results in a shift and a change of the extinction ratio of the resonances, and therefore, in the overall MMCR transmission spectrum.…”

“…The main advantage of the magnetic field sensor is its high polarization sensitivity. An asymmetric change in the intensity of the transmission spectrum [6,7] is used to analyse the magnetic field sensitivity of the device.…”

Photoelectric Hybrid Current Sensor Combination of LPCT and FFI

“…In the past decades, mechanisms including optical Faraday effect [1][2][3][4][5], magnetostrictive effect [6][7], piezoelectric effect [8][9], ferrofluid [10][11][12], and magnetic force [13,14] etcetera have been explored. The fiber sensor principles that are coupled with these mechanisms were well proposed, such as polarization modulation, fiber interferometer, and fiber gratings.…”