Up-conversion luminescence research of Er(0.5):ZBLAN material for volumetric display application when excited by 1520 nm laser

摘要

The up-conversion luminescence of the ZBLAN fluoride glass Er(0.5):ZBLAN, when excited by a 1520 nm semiconductor laser, is studied in this paper. The absorption and common-fluorescence spectra are also measured in order to understand the up-conversion clearly. It is found that there are seven strong up-conversion luminescence lines (406.97~m, 410.42nm), (521.97~m, 527.56 nm), (542.38~m, 549.27 nm), (654.27~m, 665.70 nm), 801.57~m nm, 819.46 nm, and 840.00 nm, which can be recognized as the fluorescence transitions of (~2G~4F~2H)_(9/2) → ~4I_(15/2) ~2H_(11/2) → ~4I_(15/2), ~4S_(3/2) → ~4I_(15/2), ~4F_(9/2) → ~4I_(15/2) ~4I_(9/2) → ~4I_(15/2) (~2G~4F~2H)_(9/2) → ~4I_(9/2), and ~4S_(3/2) → ~4I_(13/2) respectively. Meanwhile, the small up-conversion fluorescence lines 379.20nm, 453.10nm and 490.60nm are the transitions of ~4G_(11/2) → ~4I_(15/2), ~4F_(5/2) → ~4I_(15/2) and ~4F_(7/2) → ~4I_(15/2) respectively. It is interesting that the slopes of log F―logP curves, the double-logarithmic variation of up-conversion luminescence intensity F with laser power P, are different from each other for these observed up-conversion luminescence, this being valuable for the volumetric display. Comprehensive discussions find that the ~4G_(11/2) → ~4I_(15/2), (~2G~4F~2H)_(9/2) → ~4I_(15/2), (~2H_(11/2) → ~4I_(15/2), ~4S_(3/2) → ~4I_(15/2), ~4F_(9/2) → ~4I_(15/2)), and ~4I_(9/2) → ~4I_(15/2) up-conversion luminescences are five-photon, four-photon, three-photon, and two-photon up-conversion luminescences respectively. It is found also that the absorption from ground-state ~4I_(15/2) level to ~4I_(13/2) level is very large, which is beneficial to the sequential energy transfer up-conversion to occur.