Enhanced 1–5 μm near- and mid-infrared emission in Ho3+/Yb3+ codoped TeO2-ZnF2 oxyfluorotellurite glasses

Abstract

Intense 1–5 μm infrared emission from near- to mid-infrared was obtained from Ho3+/Yb3+ codoped TeO2-ZnF2 oxyfluorotellurite glasses which were prepared by melt-quenching method under the 980 nm LD excitation, and the emission intensity can be enhanced with the increase of ZnF2 content. Judd-Ofelt analysis was used to evaluate the radiative transition parameters of the excited levels according to the absorption spectra. The stimulated emission cross section of 5I6→5I8 (1.2 μm), 5I7→5I8 (2.0 μm), 5I6→5I7 (2.85 μm) and 5I5→5I6 (4.0 μm) transitions were calculated to reach 0.639 × 10–20, 0.760 × 10–20, 0.985 × 10–20 and 0.484 × 10−20 cm2, respectively. The energy transfer coefficients (CDA) are enhanced with the increase of ZnF2 content and phonon contribution ratios of phonon assisted energy transfer process between Ho3+ and Yb3+ were figured out. Our results demonstrate that these TeO2-ZnF2 glasses, which possess good thermal stability and transparency, low phonon energy (about 600 cm−1), excellent near- and mid-infrared emission in the range of 1–5 μm wavelength, would be promising material for infrared optical fibers and infrared lasers.