Magneto-optical properties and temperature dependence of diamagnetic lead borate glasses for fiber-optical current transducer

Abstract In this paper, diamagnetic lead borate magneto-optical glasses with an improved Verdet constant, high glass-forming ability and good thermal stability were synthesized to meet the design requirements of fiber-optical current transducers (FOCTs). The structure and performance indexes of the glasses were characterized by Raman spectroscopy, Fourier transform infrared (FT-IR) spectroscopy and X-ray diffraction (XRD). The Verdet constant of the glass samples can reach 0.1757 min/(G cm) at 633 nm, indicating excellent magnetic rotation properties. In practical applications, FOCTs are often used in complex industrial environments that require high temperature stability. To test the temperature dependence of the diamagnetic lead borate glasses, we constructed a dual-light-path variable-temperature magneto-optical modulation system. The experimental data show that the Verdet constant decreases slowly with increasing ambient temperature; thus, we theoretically analyzed the magneto-optical properties of the diamagnetic glass and the cause of its temperature dependence according to the discrepancy between the experimental results and the Becquerel formulas. We also obtained an empirical formula by fitting the Verdet–temperature curve, thereby providing an evaluation basis and a screening method for further development of FOCT materials.