Growth, High Optical Transmittance, and Strong Magneto-Optical Properties at 1550 nm of Ce,Bi-Codoped Tb ₃ Fe ₅ O ₁₂ Crystals

This paper focuses on the enhancing effect of doped Bi3+ and Ce3+ ions on the specific Faraday rotation angle of the terbium iron garnet (TIG) magneto-optical crystal. By means of structural design, a large-radius Ce3+ is doped into the dodecahedron sites of the bismuth-doped terbium iron garnet (Bi:TIG) structure. The cell volume of the crystal is enlarged to accommodate higher content of Bi3+ and Ce3+. Centimeter-sized, high-quality cerium- and bismuth-codoped terbium iron garnet (Ce,Bi:TIG) and Bi:TIG crystals were successfully grown by the top-seeded solution growth (TSSG) method using a lead-free Bi2O3–Fe2O3 flux. Among these as-grown crystals, the transmittance of Ce0.13Bi0.60Tb2.27Fe4.85Ga0.15O12 is 70.7% and the specific Faraday rotation angle is up to −800 deg cm–1 at 1550 nm. The Faraday rotation temperature coefficients (FTC) and the wavelength coefficients (FWC) of Ce0.13Bi0.60Tb2.27Fe4.85Ga0.15O12 are −1.72 × 10–3 K–1 and 1.40 × 10–3 nm–1, respectively. Ce,Bi:TIG crystal is expected to be applied in magneto-optical isolators at 1550 nm.