Magneto-optical effect of rare-earth-rich borate glasses prepared using a levitation technique

The magneto-optical properties of rare-earth-rich borate glasses prepared using a levitation technique were thoroughly investigated. Among the series of rare-earth borate glasses, Tb₂O₃–B₂O₃ and Dy₂O₃–B₂O₃ glasses displayed remarkably large Faraday effects in the visible region. The Verdet constant of 58Tb₂O₃–42B₂O₃ reached −229 rad/T·m at 633 nm, surpassing the value of commercially available single-crystalline Tb₃Ga₅O₁₂. Compositions with a higher rare-earth oxide content (60 mol%) than that of binary glasses facilitated the successful synthesis of Tb₂O₃–Dy₂O₃–B₂O₃ ternary glasses. The Verdet constant linearly increased with increasing Tb₂O₃ content for the glasses with 40 mol% B₂O₃. Results indicate that rare-earth-rich borate glasses are promising candidates for magneto-optical applications in the visible region, and that the types and amounts of rare-earth ion mainly affect these properties.