Enhanced mid-IR emission in Yb 3+–Tm 3+ co-doped oxyfluoride glass ceramics

Abstract

Tm 3+–Yb 3+ co-doped transparent oxyfluoride glass ceramics were prepared through thermal treatment of the as-prepared glasses. The precipitation of nanocrystals and the incorporation of Tm 3+ and Yb 3+ into the nanocrystals were confirmed by X-ray diffraction and absorption spectra. Based on the Judd–Ofelt theory, the J–O parameters Ω λ ( λ = 2, 4, 6), spontaneous radiative transition rates, radiative lifetimes and fluorescence branching ratios of Tm 3+ in both as-prepared glasses and glass ceramics were calculated. Intense mid-IR emission and upconversion luminescence in the Tm 3+ and Yb 3+ co-doped glass ceramics were observed under 980 nm excitation. Especially, compared with that of the as-prepared glasses, mid-IR luminescence intensity of Tm 3+ in the glass ceramics was greatly enhanced. Desirable spectroscopic characteristics suggest that these oxyfluoride glass ceramics may be promising mid-IR laser active medium.