The study of optical fiber ring interference weak magnetic field sensor

Using magnetostrictive material as sensing elements, Combined with multi-beam interference phase detection measurement of the weak magnetic field. Based on the Jiles-Atherton model, the selected magnetostrictive material piezomagnetic equation and the relationship between the magnetostrictive material´s strain and the magnetic field strength are derived, the coupling theory of Young´s modulus between the magnetostrictive material and fiber material is analyzed. Optical fiber mechanical properties for the magnetostrictive effect is amended. The coupler equation is used to analyze this kind of optical fiber ring cavity weak magnetism sensing principle, and the expression between the output of optical phase of the sensor and under test magnetic field strength is obtained., The experiment realizes this weak magnetic sensor. Matlab software is used to simulate the output phase waveform curve in different magnetic field strength. The experiment ´s results show that, the phase measured curve of the sensor outputs and the theory simulation curve anastomoses well, the resolution ratio of the magnetic field is 1.74 × 10^-5T, verifying the correctness of the theoretical arithmetic and the feasibility of the system proposal. It has certain reference significance to the magnetic field surveying work.