Magnetic field measurement with temperature compensation based on a fiber ring microwave photonic filter and Vernier effect.

We proposed, a novel, to the best of our knowledge, magnetic field measurement with temperature compensation based on a fiber ring microwave photonic filter (FR-MPF) and a Vernier effect. The sensing head is made up by attaching the fiber Bragg grating (FBG) on the magnetostrictive material. Based on the wavelength division multiplexing, two FR-MPFs with different optical carriers can eliminate the influence of the temperature. The Linear chirped FBG (LCFBG) in the FR can transfer the magnetic field variation to the time delay change as well as the frequency shift. Two FR-MPFs with close free spectral ranges can implement the Vernier effect, which can improve the sensitivity. The experimental results show the sensitivity is 58.3 kHz/Oe and the magnification factor is 214. The proposed sensor has merits of high resolution, high sensitivity and low cross-sensitivity, which has potential applications requiring high precision detections.