A Linear Magnetooptic Current Sensor Based on S-Waveplate

A novel magnetooptic current sensor (MOCS) based on the S-waveplate is proposed, which enables the linear demodulation of the Faraday rotation angle, thereby addressing issues of nonlinear demodulation and optical power dependency. The S-waveplate MOCS converts the Faraday rotation angle into the displacement of bright and dark interference fringe spots, and the displacement is then determined to directly measure the Faraday rotation angle. The S-waveplate is a continuous device that can achieve 100% polarization conversion, and a high-resolution image acquisition is designed to precisely locate the spot, so the S-waveplate MOCS shows a high current sensitivity. The experimental results demonstrate that the proposed MOCS achieves a 0.2 class accuracy with the current sensitivity of 0.093 A/px and exhibits strong robustness and reliability in the temperature test.