Observation of avalanche-like behavior in Tm 3+ : Y 2 O 3

Characterization of up-conversion processes in Tm3+-doped LiNbO3

“…5, indicating that this manifold acts as donor level as it is required in an avalanche process [10,17]. This behaviour is similar to that found in other Tm 3+ -doped materials under different pumping schemes where several excitations paths have been proposed [9,10,[17][18][19]. In the present case the confirmation of the avalanche mechanism needs further studies.…”

“…It can be observed that 1 G 4 luminescence has been increased by several orders of magnitude in comparison with that of the 1 D 2 multiplet. Additionally, the 475 nm intensity does not follow a simple power dependence but continuously increases with the pump power, suggesting an avalanche-like behaviour [9,10,[17][18][19]. Lifetime measurements of the 1 G 4 level as function of Tm 3+ concentration confirms a monotonic decrease with concentration, as it can be observed in Fig.…”

Steady State Analysis of Photon Avalanche Effect

“…large values of β) will be more efficient than avalanche since, using a single beam, a strong ground state absorption is obtained without increasing substantially the pump power. From this result, we conclude that Tm3+ doped materials are probably the most efficient for nonresonant, single-source pumped up-conversion since they exhibit the smallest detuning between pump and ground state electronic absorption [18,19].…”

Multiphonon Absorption and Photon Avalanche Criterion in Erbium Doped Materials

“…5, where 10 -4 < β < 1, corresponds to cases for which the losses in the feed-back loop may exceed the loop gain for R2 values below R2c , so that after a number of "looping" of the excited population between level 3 and the metastable level 2, the system would not diverge and maintain n 3 independently of R1. Such cases have been called "looping mechanism" [14] and we believe that some of the reported cases of qnasi-zero threshold avalanche cases in the literature [11,15] belong to large 10 -3 < β < 1 cases for which, as shown in Fig. 5, it is very difficult to distinguish between avalanche and sequential two-photon absorption (ESA).…”

“…We shall compare our results numerically with other cases of avalanche [10] or with cases which have been called "looping effects" [14] or "quasi-avalanche" ones [15].…”