Different processes responsible for blue pumped, ultraviolet and violet luminescence in high-concentrated Er3+: YAG and low-concentrated Er3+: YAP crystals

Ultraviolet and violet upconverted luminescence in high-concentrated (8.4 at%) Er3+ :YAG and low-concentrated (1 at%) Er3+ :YAP crystals has been investigated under blue laser excitation of the F-4(7/2) multiplet. The upconversion mechanisms were studied in detail based on upconversion luminescence intensity dependence and decay curves. Upconversion luminescence was attributed to energy transfer processes in Er3+ :YAG and excited state absorption processes in Er3+ :YAP, respectively. (C) 2007 Elsevier B.V. All rights reserved.