Magneto-optical and luminescent properties of Tb doped Ge-B-X (X=Ga/La) glasses

Extensive efforts have been devoted to magneto-optical (MO) glass, owing to its remarkable potential in modern optics, encompassing diverse applications such as optical isolation, modulation, and sensing. Although the Tb ions doped glass has good MO properties, high concentrations of Tb ions tend to cluster, resulting in glass crystallization. To further improve the performance of magneto-optical glass, we must improve the solubility of Tb ions and inhibit the oxidation of paramagnetic Tb3+ to diamagnetic Tb4+ by adjusting the glass composition. In this work, we conducted a comparative study on GeO2-B2O3-X2O3 glasses doped with a fixed concentration of Tb (TGBX, where X represents Ga or La) to elucidate the effects of Ga2O3 and La2O3 on glass properties. Ga2O3 is commonly regarded as a network intermediate, while La2O3 functions as a modifier in glass structure, leading to distinct differences in glass properties and cation valence. Our findings reveal that TGBG glasses exhibit superior MO performance compared to TGBL glasses. Notably, the Verdet constant of TGBG glass with 45 mol.% Tb2O3 at 650 nm reaches 105 rad/(T·m). On the other hand, though TGBL glass exhibits a lower Verdet constant, its higher glass network connectivity and a higher concentration of Tb3+ ions among Tb ions suggest its potential for preparing larger-sized glasses with an increased Tb molar ratio.