Down-Conversion From Blue to Near Infrared in Tm³⁺–Yb³⁺ Codoped Y₂O₃ Transparent Ceramics

Down-conversion from blue to near infrared (NIR) has been demonstrated inTm³⁺–Yb³⁺codopedY₂O₃transparent ceramics. Upon the 464-nm excitation, the energy transfer (ET) mechanisms consisted of theTm³⁺:¹G₄→ 2Yb³⁺:²F5/2cooperative down-conversion and the phonon assistedTm³⁺:¹G₄+Yb³⁺:²F7/2³⁺:³H₅+Yb³⁺:²F5/2cross relaxation. The low quantum yield of the latter process, together with the low absorption cross section ofTm³⁺at 464 nm and the low quenching concentration ofYb³⁺in theY₂O₃host, made theYb³⁺1030-nm NIR emission too weak for practical application.