Magnetic field optical sensors using (TbY)IG crystals with stripe magnetic domain structure

In this paper, a new type of magnetic field optical sensor based on Faraday effect created by the magnetization rotation process in each stripe magnetic domain is proposed. For these sensors, (Tb_0.19Y_0.81)₃Fe₅O₁₂ ((TbY)IG) crystals were used as Faraday element. At the wavelength of 1.3 μm, the obtained sensitivity is 4.7×10^-3 %/A/m. The small linearity error of the sensor output is also obtained in a wide dynamic range between 1 A/m and 10⁴ A/m. When the magnetic field is applied perpendicularly to the easy axis, we consider that a linear magnetization curve without hysterisis is obtained by a rotation of domain magnetization. This assumption is confirmed by experiment. The experimental results such as the sensitivity, the linearity error and the signal-to-noise ratio were explained well by the proposed model.