The Er ions were selectively excited by a frequency doubled Nd:YAG pumped OPO pulsed laser tuned in several fundamental absorptions: 1.5, 0.98 micrometro and 0.78 micrometro. The upconversion dynamics of Er (4S3/2, 4F9/2) fluorescences were investigated by time resolved spectroscopy in Er doped fluorozirconate and fluoroindate glasses with Er concentration varying from 1 to 20 %. Nonradiative decay in these glasses is mainly originated from the migration assisted cross relaxation of 4F3/2:4I9/24I15/2:4I15/2 type among the neighbouring Nd3+ instead of a direct energy transfer from Nd3+ to OH. On the other hand, an exponential behaviour was dominant for glasses containing more than 0♵ wt% Nd2O3. The critical transfer distance (R0) is approximately 0♴6 nm. In this case, a direct energy transfer from Nd3+ to OH- was responsible for the decay. nonexponential decaying behaviour following the relationship of exp(t0♵) where t represents a time scale. For glasses with low concentration 0♰5 wt% Nd2O3, intensity of the emission showed a. Analyses on the decaying behaviour of 1♳5 µm fluorescence from the 4F3/24I13/2 transition in Nd3+ suggested the presence of two different energy transfer mechanisms between Nd3+ and OH. Read moreĮffects of the spurious OH- on the emission characteristics of Nd3+ doped PbO≫i2O3Ga2O3 glasses were investigated. It was suggested that at the lower concentration of ErF3 (⩽2 mol %), we needed to use the distance between Er3+ ions which was shorter than that as the cubic structure in the calculation of the energy transfer rate. With increasing the ErF3 concentration, the calculated energy transfer rate when the Er3+ ions were dispersed as the cubic structure was comparable to the measured energy transfer rate. It could be shown that the calculated energy transfer rate assuming that the Er3+ ions were dispersed as the cubic structure was closer to the measured energy transfer rate than that as the bcc and fcc structures. The energy transfer rate estimated from the rate equation calculation was compared with the energy transfer rate obtained from the lifetime measurement. The energy transfer rate can be derived from the total transition rate. Although many studies have reported the energy transfer rates in various rare-earth ions, the reliability of the calculated energy transfer rates has been hardly discussed. total transition rate of the 4S3/2 state of the Er3+ ion on the ErF3 concentration was calculated by using the rate equation and compared with the total transition rate measured by the lifetime experiment. Energy transfer rates were calculated from optical parameters assuming that the Er3+ ions in fluorozirconate glasses were dispersed as the cubic, bcc, or fcc structure, and were inserted into the rate equation. The dependence of the fluorescence lifetime of the 4S3/2 state of the Er3+ ion on the ErF3 concentration was measured in fluorozirconate glasses at room temperature. (Ired/Igreen) is increased in AYF and AZF glass,and the red emission intensity in these gass depends on (Pex)1.6.They are mainly due to a cross-relaxation process between two erbium ions,one in the 4S3/2 and the other in the 4I9/2.In Tm3+-Yb3+ co-doped AlF3-based flouride glass,the concentration quenching of Tm3+ in blue at 476nm is stronger than that in infrared light at 793nm,and the optimum content of Tm3+ for 476nm emission is about 0.1mol%,while it is (0.3-5)mol% for 793nm emission.The concentration quenching of Yb3+ to upconvertion fluorescence is also observed.It may be due to the back-energy transfer from the 3F4 level of Tm3+ to the 2F5/2 level of Yb3+. Energy transfers and upconversion fluorescence spectroscopy in both Er3+ singly doped and Tm3+-Yb3+ co-doped AlF3-based flouride glass,excited at 970nm,are investigated experimentally.In Er3+:AYF glass,the optium Er3+content for 550nm emission is about at 6mol%,which is 12mol% in AZF glass.With the increase of Er3+ content,the intensity ratio of the red emission to the green emission.
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