Effect of temperature on excitation energy transfer and upconversion phenomena in Er:YVO4 single crystals

Investigation of excitation and decay of Er3+ in YVO4 single crystals has been carried out at temperature range from 5 to 500 K. In the limit of low Er3+ content, the temperature dependence of the S-4(3/2) decay is not consistent with predictions of multiphonon relaxation model. In heavily doped crystals the 4S(3/2) decay is governed by cross relaxation process, whose rate grows steadily with increasing temperature. An efficient upconverted luminescence near 550 nm following a cw and short pulse (5 ns) excitation of the I-4(9/2) level in the system under study has been recorded and analysed. Contribution of the excited state absorption to these phenomena has been considered. (C) 2001 Elsevier Science B.V. All rights reserved.