Upconversion properties of Tm~(3+)/Yb~(3+) codoped fluorophosphate glasses with low phonon density of states

摘要

Fluorophosphate glasses codoped with Tm' and Yb' were prepared and their thermal stability, phonon states, and upconversion properties were studied. It is found that the increment of phosphate content is good for the thermal stability but increases the phonon density of states. However, the phonon density of states of these fluorophosphate glasses is very low due to the low phosphate content in their composition. The upconversion luminescence spectra were measured under excitation of 970 tun laser diode, and the intense blue (476 mn) and near infrared (794 nm) emission were simultaneous obtained at room temperature. The sensitizing mechanisms of Yb~(3+) to Tm~(3+) for blue and red emission contain both sequential and cooperative sensitization. The near infrared emission is a two-photon upconversion process. These researches suggest that when the phosphate content in the composition is low enough, fluorophosphate glass can be suitable host material of TmJT codoped with Yb~(3+) for blue and near infrared upconversion luminescence.