Magnetooptic Sensor Based on Electrogyration Compensation for Faraday Effect in Lead Molybdate Crystal

A novel magnetooptic sensor is proposed which is based on electrogyration compensation for the Faraday rotation angle in single lead molybdate (PbMoO₄, PMO) crystal. The optical sensing unit is only composed of two polarizers and one single PMO crystal exhibiting both the Faraday and electrogyration effects. AC 50-Hz magnetic field in the range of 167 Gs has been measured by the method of electrogyration compensation, and the nonlinear error is <1.2%. The compensating voltage is ∼ 16 V/Gs for a block of PMO crystal with 5 mm in length. Verdet constant of the PMO crystal sample has also been measured for light wavelength of 635 nm, and it is ∼ 51.6 ± 1.1 rad. T^-1. m^-1. The proposed magnetooptic sensor provides a promising closed-loop measurement method of current, magnetic field, and Verdet constant.