OPTICAL MAGNETIC-FIELD SENSORS WITH NIGH LINEARITY USING BISUBSTITUTED RARE-EARTH IRON GARNETS

Optical magnetic held sensors with high linearity were developed. Bi-s ubstituted rare earth iron garnets were prepared using the liquid phas e epitaxy method for use as the Faraday rotators of the sensors, The l inearity error of the sensor output was obtained within 1.0% for alter nating magnetic fields of up to 300 Oe. The sensor optical system has a new converged beam optical system using ball lenses. The linearity o f these sensors is much better than that of sensors using a collimated beam optical system with graded index tenses. Sensors using the colli mated beam optical system are nonlinear, since only the zeroth-order b eam diffracted by the garnet maze domains is detected, Sensors using t he converged beam optical system have high Linearity because of the de tection of diffracted beams up to the second-order. The experimental r esults agreed well with the calculated results.