Temperature dependent luminescence in erbium-doped zinc tellurite glass: A model investigation

Abstract

Temperature quenching characteristics of infrared-to-visible frequency up-conversion (UC) in erbium doped zinc tellurite glasses under infrared excitation 797 nm are presented. A comprehensive 4-level model has been developed and the derived rate equations have been exploited to examine the thermal quenching of efficiency and emission intensity for the UC. The green (⁴S_3/2→⁴I_15/2) and red (⁴F_9/2→⁴I_15/2) emissions over a temperature range 10-340 K and at concentration 2.0 mol% have been studied. The green emission shows a continuous increase with decrease of temperature while the red emission is not that sensitive to temperature. In addition, the temperature dependence on the multi-phonon relaxation rates is fitted with 4 phonons processes. These features are attributed to the non-radiative (NR) energy transfer processes, trapped impurity effects and thermal assisted hopping. It is further indicated that to achieve higher infrared to visible up-converted efficiency in zinc tellurite glasses the NR channels for energy and charge transfer by phonon and impurity mediated process has to be minimized. Our results on pump power dependent emission intensity, quantum efficiency, luminescence intensity and NR multi-phonon relaxation rates are in conformity with other findings. The present systematic study provides useful information for further development of UC lasers