Optical magnetic field sensor improved by NdFeB ferromagnetic film

In this paper, two types of optical magnetic field sensors have been prepared, one was pure garnet magnetic field sensor, another was garnet with Ta/NdFeB/Ta film grown by magnetron sputtering method at the base pressure of 1.0×10 -5 Pa, and the working pressure was 0.8Pa. Ta film worked as buffer layer and protective layer, and the NdFeB worked as ferromagnetic film, the atom proportion of NdFeB was 2:14:1. The measuring was based on Magneto-optical Faraday effect. The Faraday rotation was obtained under the conditions of 1.55μm near-infrared light and the magnetic field in range of -150-150Oe. It was found that the garnet sensor with NdFeB film has lower linearity error 0.125% compared with pure garnet sensor 1.42%, and the difference was attributed to the presence of NdFeB ferromagnetic film interact on the garnet.