CC BY
18LS-O-3
Laser spectroscopy of a new CaSrBaF6: Tm3+ crystal
Alimov O.K., Doroshenko M.E., Konyushkin V.A., Kuznetsov S.V., Nakladov A.N.,
Nekhoroshikh A.V, Pierpoint K.A.
Prokhorov General Physics Institute of the Russian Academy of Sciences e-mail: pierpoint@lst.gpi.ru
A new four-component CaSrBaF6:Tm3+ crystal has been grown by the Bridgman technique. The spectroscopic properties of Tm3+ ions in the crystal at two-micron transition were studied by the laser selective excitation technique. Previously synthesized CaSrBaF6 single crystals demonstrated wide transparency spectral range [1]. The newly grown optical quality CaF2(39.5%)SrF2(40%)BaF2(20%):TmF3(0.5 mol. %) single crystal (see Fig.1) demonstrates that such compounds (CaSrBaF6) are quite suitable for doping with rare-earth ions.
The X-ray phase analysis of the sample showed it is single-phase with face-centered cubic lattice with a lattice parameter a = 5.747 A being close to SrF2 one - 5.800 A. The absorption spectra of CaF2:Tm3+, SrF2:Tm3+, BaF2:Tm3+, and CaSrBaF6:Tm3+ crystals measured at the 3H6^3H magnetic dipole allowed transition at T = 77 K are presented in Fig.1. Certain Tm3+ ions absorption bands at this transition in CaF2, SrF2 and BaF2 crystals were attributed to the cubic (Oh), tetragonal (C4v), and clustered centers in [2,3], As can be seen from Fig. 1, the CaSrBaF6:Tm3+(0.5 mol. %) crystal has a spectrum which reminds that of BaF2:Tm3+ crystal with relatively narrow intensive absorption lines in the region of cubic (1190 nm) and clustered Tm3+ centers absorption (1200-1220 nm) [3].
CaSrBaF :Tm3+(0.5%) T-77K
6
O CaF2:Tm3+(0.4%) A
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o
m
3
SrF :Tm(0.4%)
2 BaF2:Tm(0.15%)
CaSrBaF :Tm(0.5%) Xxc = 1206 nm
t =0.6ms, T=77K
it =60ms, T=77K
l del '
1600
1700
1800 1900 2000
Wavelength, nm
2100
Fig. 2 - Time-resolved fluorescence spectra of Tm3+ ions at the 3F4-3H6 transition in CaSrBaF6:Tm3+(0.5 %) crystal at T = 77 and 300 K
1185 1190 1195 1200 1205 1210 1215
Wavelength, nm
Fig. 1 - Absorption spectra of Tm3+ ions at the 3H6-3H5 transition in CaF2, BaF2 and CaSrBaF6 crystals at T = 77 K
The time-resolved Tm3+ ions fluorescence spectra at the 3F4^3H transition measured under ^exc = 1206 nm excitation into the clustered centers absorption band at T = 300 and 77 K are shown in Fig. 2. In a low-temperature spectrum for long delay time of tdel = 60 ms two lines at the long-wavelength spectrum edge were observed. The spectral positions of these lines correspond well with that of Tm3+ long-lifetime center in BaF2 crystal [3].
The Tm3+ ions fluorescence decay curves of 3F4 level at T = 77 and 300 K were measured at 1868 nm (the maximum of the fluorescence spectrum) under 1206 nm excitation. The Tm3+ ions lifetime measured at T = 300 K was «21.5 ms. Decay curve recorded at T = 77 K consisted of two exponents with lifetimes of «7.0 and «21.5 ms. Under excitation into the weak absorption band with a maximum of X = 1187.4 nm (Xdet = 1868 nm; T = 300, 77 K) decay was a sum of two exponents with lifetimes of «12.5 and «67.0 ms. The short component decay time (12.5 ms) is in good agreement with the lifetime of clustered Tm3+ center in BaF2 [3]. The long component lifetime was practically independent on temperature while its intensity was observed to increase from 300 to 77K.
[1] S.N. Ushakov, M.A. Uslamina, A.A. Pynenkov, V.P. Mishkin, K.N. Nishchev, S.V. Kuznetsov, E.V. Chernova, P.P. Fedorov, Growth and physical properties of CaSrBaF6 single crystals. Condensed Matter and Interphases, 23(1), 101-107. (2021).
[2] M. Bouffard, J.P. Jouart, M.-F. Joubert, Red-to-blue up-conversion spectroscopy of Tm3+ in SrF2, CaF2, BaF2 and CdF2, Optical Materials, vol. 14(1), pp. 73-79, (2000).
[3] O.K Alimov, M.E. Doroshenko, V.A. Konyushkin, A.N. Nakladov, A.G. Papashvili, V.V. Osiko, Spectroscopic properties of Tm3+ optical centers at the 3F4-3Hi 2-^m laser transition in BaF2 crystal. Journal of Luminescence, vol. 172, pp. 219-223, (2016).
