Luminescence properties of PrF_3-doped Sb_2O_3-ZnO-GeO_2 glass phosphors for near-infrared wideband light-source

摘要

We synthesized PrF_3-doped glass phosphors using a melt-quenching method and investigated the luminescence characteristic aiming at a new near-infrared wideband light-source. Optical activation of Pr~(3+) ions in the samples was confirmed by absorption spectra measurements. Broad PL spectra from 700 to 1100 nm with four PL peaks 730, 870, 930, and 1040 nm were observed by blue LED excitation in all samples. The observed PL peaks were attributed to ~3P_0 → ~3F_4, ~1D_2 → ~3F_2, ~3P_0 → ~1G_4, and ~1D_2 → ~3F_4 transitions of Pr~(3+) ions. With the increase in the PrF_3 concentration, the integrated PL intensity around 1040 nm (~1D_2 → ~3F_4) was sharply decreased compared to the other PL peaks. We investigated the contribution of self-absorption and cross-relaxation phenomena to the spectral change by measuring glass thickness dependence of the PL spectra and measuring the PrF_3 concentration dependence of the fluorescence lifetimes. The fluorescence lifetime of the PL peak at 1040 nm decreased with increasing PrF_3 concentration owing to a non-radiative relaxation pathway stemming from the cross-relaxation phenomena. We found that the cross-relaxation phenomenon is a dominant factor in the luminescence properties of PrF_3-doped glass phosphors.