Avalanche-like mechanisms and up-conversion processes under infrared pumping in Ho3+, Yb3+:YAlO3

Multi-wavelength visible up-converted luminescence in novel heavily doped Ytterbium–Holmium silica fiber under low-power IR diode pumping

“…This choice of the co-dopants' concentrations was based on a study of preliminary-prepared fibers and the available data on optimal percentage of the co-dopants' in Yb-Ho-doped bulk crystals and glasses [10][11][12][13][14][15][16][17][18][19], which provides a maximum yield of visible luminescence at IR pumping.…”

“…Among them, silica fibers activated with holmium (Ho), or co-activated with Yb and Ho [4][5][6][7][8][9][10] are of a special interest since these fibers can be an alternative for communications purposes in a 2-mm spectral range and for the lidar and medicine applications. Yb-Ho-doped fibers can be also used as an amplifying medium for the frequency- On the other hand, as far as we know only the recent work [8] reports on an analysis of Yb-Hodoped silica fiber as a potential material for lasing at wavelength 2.1 mm at IR pumping, where the up-conversion mechanism [11], the effect wellknown in Yb-Ho-co-doped bulk crystals and glasses [12][13][14][15][16][17][18][19], is shown to be quite effective.…”

“…We show that the conventional mechanisms of energy migration from Yb 3+ to Ho 3+ and stepwise up-conversion within the Yb 3+ -Ho 3+ mixed system that is a consequence of a series of excited-state absorption (ESA) transitions are the processes highly effective in the Yb-Ho fiber as those in crystals [11][12][13][14][15][16][17][18][19]. We also discuss an avalanche-like character of the up-conversion process in the fiber and an additional channel of excitation of the Ho 3+ sub-system via an energy transfer from the Yb 3+ ion pairs [20][21][22][23].…”

Growth and properties of 20at% Yb3+-doped YALO3 single crystal

“…5. The up-conversion luminescence of these ions is excited by infrared light through two-or three-step energy transfer from Yb 3+ ions in general [12,17]. In addition, it is noted that the relative intensity of cooperative emission around 500 nm is very weak, which implies that the cooperative sensitization luminescence mechanism [19,20] caused by de-excitation of two excited Yb 3+ ions is also involved in the up-conversion luminescence shown in Fig.…”

“…impurities in 20 at%-doped Yb:YAP crystal. According to the energy-level configurations and their emission features of Tm 3+ , Er 3+ , and Ho 3+ ions in the YAP crystal [14][15][16][17][18], the luminescence at 475 nm shown in Fig. 5 probably originates from the transition 1 G 4 -3 H 6 of Tm 3+ ions, the emission band peaked at 550 nm may be assigned to the transition 5 S 2 -5 I 8 of Ho 3+ ions and the transition 4 S 3/2 -4 I 15/2 of Er 3+ ions, and the transition 1 G 4 -3 H 4 of Tm 3+ ions and the transition 5 F 5 -5 I 8 of Ho 3+ ions may be responsible for the up-conversion luminescence centered at around 660 nm in Fig.…”