Faraday Effect Optical Current/Magnetic Field Sensors Based on Cerium-Substituted Yttrium Iron Garnet Single Crystal

Optical current/magnetic field sensor based on creation of the Faraday rotation effect in cerium-substituted yttrium iron garnet single crystal has been presented. Here we focus our studies on improving the magneto-optical properties and sensitivity constant of Ce:YIG Faraday sensor element through compositional modification. Due to the Ce³⁺ ions substitution, the specific Faraday rotation of Ce_0.29Yb_0.08Y_2.63Fe_4.72Ca_0.28O₁₂ single crystal under saturation magnetic field was enhanced greatly to be about 761.7 deg/cm and -614.1 deg/cm at 780 nm and 1150 nm wavelength respectively. Magneto-optic figure of merit reaches 67.1 deg/dB at 1150 nm wavelength and room temperature. The sensitivity have been enhanced by a factor of 31.1 with respect to pure YIG, given the same sensor length and demagnetization factor, by substituting Ce ions into Y sites and substituting diamagnetic Ca ions into Fe sites in YIG. Furthermore, a laboratory prototype of hybrid optical fiber current/magnetic field sensor using Ce:YIG bulk single crystal as a Faraday element was proposed and its sensing performance was also tested.