Developments in Ceramic Materials Research

70
Fluorescence, a.u.
1
0.1
0.01
0.001
2
T. T. Basiev, V. A. Demidenko, K. V. Dykel’skii et al.
6
4 I11/2
T=300 K 3
4
1
1 CaF 2 :Er 3+ (5%) ceramics
λ exc =974 nm λ det =987.5 nm
τ=7.35 ms
2 ErF3 raw material for
samples with 05 index
λexc =974 nm λdet =987.5 nm
τ = 490 μs
5 CaF2 :Er 3+ (5%) ceramics
λexc =974 nm λdet =987.5 nm
τ=7.9 ms
0.0001
0.00 0.01 0.02 0.03 0.04 0.05
time, s
5
3 CaF 2 :Er 3+ (5%) crystal
λ exc =980 nm λ det =987 nm
τ=9.82 ms
4 CaF 2 :Er 3+ (10%) crystal
λ exc =980 nm λ det =987 nm
τ=8.9 ms
6 ErF3 raw material for
samples with 06 index
λexc =974 nm λdet =987.5 nm
τ = 588 μs
Figure 16. Fluorescence kinetics decay of the 4 I 11/2 level measured under pulsed laser excitation in the
CaF 2: Er 3+ (5%) ceramics (В(2)39-05 sample) (curve 1), in its ErF 3 precursor (curve 2), in the CaF 2:Er 3+
(5%) (curve 3) and the CaF2:Er 3+ (10%) (curve 4) crystals, in the CaF 2:Er 3+ (5%) (В(1)3-06 sample)
(curve 5) and in its ErF3 precursor (curve 6) at room temperature.
Also, the disordered stage of energy transfer kinetics for the new CaF2: Er 3+ (5 mol. %)
(В(1)3-06) ceramic sample and its ErF3 precursor is analyzed. Analysis of the disordered
stage of energy transfer kinetics for ceramics gives the sum of two mechanisms of interaction
between the energy donors (erbium ions) and the acceptors (uncontrolled impurities), i.e.
quadrupole – quadrupole (s = 10) and dipole- quadrupole (s = 8). However, for the ErF3
precursors the only quadrupole – quadrupole interaction is observed. This result shows that in
the new CaF2: Er 3+ (5 mol. %) ceramic sample (В(1)3-06) the average distance between the
Er 3+ ions and uncontrolled impurities ions is larger, which is, to say that the latter
concentration is lower.
Fluorescence spectrum at the 4 I13/2 → 4 I15/2 transition in the CaF2:Er 3+ (5 mol. %)
(В(2)39-05) ceramic sample is measured under 810 nm CW laser excitation at room
temperature (Figure 17a). Fluorescence kinetics decay of the 4 I13/2 manifold in this sample
was measured by pulsed LiF: F2 → F2 + color centers laser excitation at 974 nm wavelength
and 1.53 μm detection at T=300 K (Figure 17b). A build - up of the fluorescence is observed
with the duration of 6 ms. Fluorescence kinetics decay at the long time scale is exponential
with the decay time τfinal = 15.7 ms. The powdered ceramic sample exhibits exponential decay
with τ = 6.7 ms which is ~3 times shorter than for the ceramic sample and indicates the
fluorescence trapping for the latter one because of high absorption cross – section at the 4 I15/2
→ 4 I13/2 transition.