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20LS-I-10 _ ALT,22
LASER SYSTEMS AND MATERIALS
Spectral-luminescent and laser characteristics of Y2O3 ceramics doped with
rare-earth ions (Ho3+, Tm3+, Yb3+)
P.A. Ryabochkina1, S.A. Artemov1, V.V. Balashov2, T.V. Volkova1, A.A. Lyapin1, I.A. Yurlov1, S.A.
Khrushchalina1
1- National Research Mordovia State University, Bol'shevistskaya 68, 430005 Saransk, Russia 2-Fryazino branch of the V.A. Kotelnikov Institute of Radio Engineering and Electronics, RAS, Vvedensky Sq. 1, Fryazino Moscow region, 141120, Russia Main author email address: ryabochkina@ffreemal.mrsu.ru
The features of the rare-earth ion energy terms splitting into Stark sublevels in the crystal field of ligands in sesqui-oxides Ln2O3 (Ln - Y, Lu, Sc, Gd) and the high thermal conductivity of these materials provide considerable interest for their use as active media of solid-state lasers with a high output power radiation [1-3]. Growing sesquioxides (Ln - Y, Lu, Sc, Gd) Ln2O3 from melt is difficult due to their high melting point (>2400°C)]. Therefore, technologies for obtaining laser ceramics of sesquioxides doped with various rare earth (RE) ions are currently being actively developed, which ensure their production at lower temperatures. Of considerable scientific and practical interest are Ln2O3 (Ln - Y, Lu, Sc) crystals and ceramics doped with Tm3+ and Ho3+ ions for their use as active media of solid-state lasers generating radiation in the two-micron spectral region.
The report presents the results of a study of the spectral-luminescent and laser characteristics of domestic Y2O3:Yb, Tm and Y2O3:Ho ceramics obtained by solid-phase sintering. Previously, we obtained for the first time continuous-wave lasing at the 3F4^3H6 transition of Tm3+ ions (^gen= 195 ^m, ^gen= 2.05 ^m) pumped to the 3H4 level by a semiconductor laser diode (A,pump~800 nm) on Y2O3:Tm ceramics (CTm=1.7 at .%) [4]. With this method of pumping, the population of the upper laser level 3F4 of Tm3+ ions occurs as a result of radiative and nonradiative processes from the 3H4 level, as well as cross-relaxation of Tm3+ ions (3H4^3F4, 3H6^3F4), which is an important channel for the population of the 3F4 level of Tm3+ ions when creating population inversion at the 3F4^3H6 transition. An alternative way to obtain two-micron lasing on the 3F4^3H6 transition of Tm3+ ions is the use of active laser media based on a crystalline matrix co-doped with Tm3+ and Yb3+ ions [5]. When Yb3+ ions are pumped to the 2F5/2 level the 3H5 level of Tm3+ ions is populated according to the scheme Yb3+ (2F7/2^2F5/2) ^ Tm3+ (3H6^3H5) as a result of nonradiative energy transfer from Yb3+ ions to Tm3+ ions. Further, the excitation nonradiatively relaxes from this level to the upper 3F4 laser level of these ions.
In the course of this study of the concentration series ofY2O3:Yb, Tm (CYb = 6, 10, 15 at.%, CTm = 1 at.%), Y2O3:Yb, Tm (CYb = 6, 10, 15 at.%, CTm = 3 at.%) ceramics, we revealed an effective nonradiative energy transfer from Yb3+ ions to Tm3+ ions, as well as the interaction between Tm3+ ions. We have analyzed the luminescence spectra due to the 1G4^3H6, 1G4^3F4, 3F3^3H6, 3H4^3H6, transitions and the luminescence decay curves from the 1G4, 3F3, 3H4, 3F4 levels, Tm3+ ions, recorded upon excitation of the 2F5/2 level of Yb3+ ions for concentration series of ceramics Y2O3:Yb, Tm, and proposed mechanisms for populating and unloading the energy levels of Tm3+ and Yb3+ ions.
Also, for the first time, we obtained lasing at the %^5I8 transition of Ho3+ ions in domestic Y2O3:Ho ceramics (CHo = 0.5 at.%) pumped by a thulium fiber laser (A,gen=2117 nm, differential lasing efficiency 33%, Pout= 2.4 W).
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