Temperature-dependent fluorescence decay and energy transfer in Nd/Cr:YAG ceramics

Analyses of energy transfer of Cr3+ and Nd3+ co-doped Y3Al5O12 ceramic powders at the 4 T 1 level of Cr3+ ion excitation

“…τ Cr is the fluorescence lifetime of the 2 E-4 T 2 level of Cr 3+ and is temperature dependent as shown in our previous work. 21) Thermal excitation between the 2 E and 4 T 2 levels in the 2 E-4 T 2 level is described in detail. 21) τ Nd is the fluorescence lifetime of the 4 F 3/2 level of Nd 3+ .…”

“…21) Thermal excitation between the 2 E and 4 T 2 levels in the 2 E-4 T 2 level is described in detail. 21) τ Nd is the fluorescence lifetime of the 4 F 3/2 level of Nd 3+ . γ n and γ Qn are the energy transfer and quenching parameters from excited Cr 3+ ions to Nd 3+ ions and quenchers, respectively.…”

“…Where the subscript n for these parameters is 1 and 2 which respectively means the energy transfer from the 4 T 2 level and from the 4 T 1 level. The energy transfer from Cr 3+ to Nd 3+ in YAG is dominated by γ at room temperature, and W is regarded as ≈0 21) and ignored in this paper. s is 6, 8, or 10, for dipole- 6) and (7).…”

“…The coupled 2 E and 4 T 2 levels are referred to as the thermally coupled 2 E-4 T 2 level because some of the population stored in the metastable level of 2 E is thermally excited to the 4 T 2 level. 21) We previously investigated the temperature dependence [20][21][22] and concentration dependence 23) of the energy transfer process of Nd/Cr:YAG ceramics with 4 T 2 level excitation. In Nd/Cr:YAG ceramics, the energy transfer from Cr 3+ to Nd 3+ can be explained by dipole-dipole interactions, even if the concentration quenching of Cr 3+ is included.…”

“…The conclusions were explained by theory and experimental data. [21][22][23] Fujioka et al reported that the fluorescence intensity of Nd 3+ in Nd/Cr:YAG ceramic powders excited at 440 nm ( 4 T 1 level) increased with increasing Cr 3+ concentration up to 6.0 mol% and then decreased because of concentration quenching. 15) However, they could not discuss the energy transfer process in detail because the fluorescence lifetime was considered effective.…”