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

Abstract

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 (406.97m, 410.42 nm), (521.97m, 527.56 nm), (542.38m, 549.27 nm), (654.27m, 665.70 nm), 801.57m nm, 819.46 nm and 840.00 nm, which can be recognized as the fluorescence transitions of (2G4F2H)9/2?4I15/2, 2H11/2?4I15/2, 4S3/2?4I15/2, 4F9/2?4I15/2, 4I9/2?4I15/2, (2G4F2H)9/2?4I9/2 and 4S3/2?4I13/2 respectively. Meanwhile, the small up-conversion fluorescence lines 379.20 nm, 453.10 nm and 490.60 nm are the transitions of 4G11/2?4I15/2, 4F5/2?4I15/2 and 4F7/2?4I15/2 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 4G11/2?4I15/2, (2G4F2H)9/2?4I15/2, (2H11/2?4I15/2, 4S3/2?4I15/2, 4F9/2?4I15/2) and 4I9/2?4I15/2 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 4I15/2 level to 4I13/2 level is very large, which is beneficial to the sequential energy transfer up-conversion to occur.