Optical transitions of Ho3+ in YAG

We report the optical properties of Y3Al5O12 (YAG) crystal doped with Ho3+ ions. Absorption, emission, and lifetime measurements have been performed and discussed using judd-Ofelt theory. Visible emissions from the D-3(3) (at about 33 000 cm(-1)), S-5(2) (18 500 cm(-1)) and F-5(5) (15 500 cm(-1)) excited states and IR emissions from the I-5(6) level have been characterized under pulsed one-photon excitation and the experimental lifetimes for these levels have been compared with those obtained theoretically by using Judd-Ofelt approach. Upconversion processes for achieving blue and green fluorescence under one-color red and IR have been investigated. (C) 2000 Elsevier Science S.A. All rights reserved.