Small optical magnetic-field sensor that uses rare-earth iron garnet films based on the Faraday effect

Abstract

Highly accurate optical magnetic-field probe sensors that use iron garnet films have been developed. New probe-type sensors were designed with a confocal optical system. A new garnet composition, Bi(0.98)Gd(0.92)La(0.03)Y(1.07)Fe(4.72)Ga(0.28)O(12), was found that shows high temperature stability for a sensitivity of less than 2.0% from -20 to +80 degrees C. The linearity error of the sensor output was within 1.0% for alternating magnetic fields from 0.3 to 42 mT. An optical current transformer that uses the proposed sensor has an ac linearity of 1.0% for input current up to nearly 300 A. The sensor realized high performance in actual use.

Non-contact optical magnetic field sensor based on metamaterial nanomechanics

“…In contrast, optical sensors have the advantage that they can be read from a distance, enabling non-contact measurements and use in harsh environments. However, fiberized 12,13 and optical fibre magnetometers [13][14][15][16][17][18] (based on the Lorentz force, 12 Faraday effect, 14,15 magnetic fluids, [16][17][18] Fabry-Pérot cavities 17,18 and vapor cells 13 ) rely on the fibre connection for readout. Non-contact optical magnetic resonance detection based on nitrogen-vacancy centres in diamond can achieve sub-micron spatial resolution and high sensitivity, but simultaneous need for light, microwaves and external magnetic field prevents microscale integration.…”

Faraday Rotation and Sensitivity of Bi-Substituted Iron Garnet Single Crystal for Optical Current/Magnetic Field Sensors

“…However, in H II geometry, magnetization saturates at rather low magnetic field about 500 Oe which exhibits a 75% reduction in comparison with pure YIG. According to (4), this composition should increase the sensitivity by a factor of 24.1 with respect to pure YIG, given the same sensor length and demagnetization factor.…”