Vector Magnetic Field Sensor Based on Fiber Random Grating Coupled With Wavelength-to-Time Mapping

A novel fiber random grating (RG) etched on a D-shaped photonic crystal fiber coupled with magnetic fluid cladding (MF-D-PCF-RG) structure is introduced in the proposed vector magnetic field sensor. This structure supports two orthogonally polarized transmissions, the wavelength difference of which is determined by the birefringence of MF-D-PCF-RG. With the magnetic field, two polarized transmissions have different wavelength shifts, enabling the design of a vector magnetic field sensor. Improvements in measurement resolution are achieved through wavelength-to-time (WTT) mapping combined with pulse compression. When using the orthogonal reflection signal of the MF-D-PCF-RG to perform WTT mapping, two temporally separated optical pulses are generated. Following optical-to-electrical conversion, pulse compression is applied to both electrical waveforms, enhancing the interrogation resolution. The vector magnetic field is deduced by assessing the time shifts of the compressed orthogonally polarized pulses. Simulation results show that the proposed vector magnetic field sensor achieves sensitivities of 11.15 ps/Oe in the x polarization direction and 11.43 ps/Oe in the y polarization direction. The direction sensitivity reaches 23.78 ps/deg.