Many-body energy-transfer processes betweenEr3+ions in yttrium aluminum garnet

Energy transfer-driven infrared emission processes in rare earth-doped Sc2O3 ceramics

“…This process corresponds to the cooperative de-excitation predicted by Dexter [11] and the temporal dependence observed in Ref. [10] was in agreement with theoretical estimation [12]. Cooperative de-excitation was subsequently reported for systems where the donors and the acceptors were different species, such as de-excitation of Nd 3+ , Ho 3+, Tm 3+ , Er 3+ by cooperative transfer to Ce 3+ [13], or that of Tb 3+ by two Yb 3+ ions [14].…”

“…However, the transfer function P(t) for the 10 at% Er:Sc 2 O 2 ceramic, calculated with the ET parameters measured at low Er concentrations was obviously slower than the experimental function indicating that additional de-excitation paths by direct D-A transfer that become important at very high doping concentrations occur. Such behaviour was observed previously for heavily doped Er:YAG crystals [10] and it was shown that an additional contribution to the transfer function with temporal dependence in the range of t À0.3 can describe the effect. Based on the energy level diagram of Er:YAG, it was assumed that such additional de-excitation can be caused by cooperative de-excitation by which a donor excited in the levels ( 4 S 3/2 , 2 H 11/2 ) relaxes to the level 4 I 13/2 with simultaneous excitation of two Er 3+ ions from the ground level 4 I 15/2 to the level 4 I 13/2 .…”

Upconversion dynamics in Er3+-doped YAG

“…The other pathway to the 2 G 9/2 state is that one ion in the 4 I 9/2 state and one ion in the 4 F 9/2 state interact, leading to one ion in the ground state and one ion in the 2 K 15/2 state, and the 2 G 9/2 state is then populated by subsequent nonradiative relaxation. It is reasonable that ETU is the dominant upconversion process considering the concentration of Er 3+ ions (10.5 at%) and temperature (300 K) [9,32]. It can also be understood according to the energy-level data, since the two ETU processes are exactly resonant.…”

“…The upconversion luminescence of the Er 3+ ion has been studied extensively [9][10][11][12]. Upconversion laser emission, primarily in the blue, green and infrared region, has also been achieved in several Er 3+ -doped materials, including LiYF 4 [13][14][15][16][17], YAlO 3 [18], BaY 2 F 8 [19], CaF 2 [20], LiKYF 5 [21] and LiLuF 4 [22], using upconversion schemes based on ESA or ETU processes.…”

Upconversion luminescence in Er3+ doped Ga10Ge25S65 glass and glass-ceramic excited in the near-infrared

“…6(a) and 6(b) [15][16][17][18] In the present case, due to the proximity between the 4 S 3/2 level energy and the host band edge an extra term related to the energy back transfer probability, W EBT , from the excited Er 3þ ions to the host has to be included in such way that …”