Growth of (Er,Yb):YAl 3 (BO 3 ) 4 laser crystals
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L GROWTH
Growth of (Er,Yb):YAl3(BO3)4 Laser Crystals O. V. Pilipenkoa, V. V. Mal’tseva, E. V. Koporulinaa, N. I. Leonyuka, N. A. Tolstikb, and N. V. Kuleshovb a Moscow
State University, Leninskie gory, Moscow, 119992 Russia e-mail: [email protected] b Belarussian State Technical University, Minsk, 220030 Belarus Received January 17, 2007
Abstract—(Er,Yb):YAl3(BO3)4 single crystals of optical quality, up to 15 × 10 × 10 mm3 in size, have been grown from a (Er0.023Yb0.116Y0.862)Al3(BO3)4 solution in a Y2O3–B2O3–K2Mo3O10 melt. The initial borate concentration was 17 wt %, and the flux cooling rate increased from 0.08 to 0.12°C/h in the range 1060–1000°C. The physical properties of the single crystals grown are good enough that they can be used as laser elements in systems with diode pumping and radiation near 1.5 µm. PACS numbers: 81.10.Fq, 42.55.Xi DOI: 10.1134/S1063774508020260
INTRODUCTION In the family of new functional borates, the most effective lasing near 1.5 µm was obtained on an Er,Yb:Ca4YO(BO3)3 crystal [1]. With diode pumping, a differential efficiency as high as 26.8% was obtained, whereas that for phosphate glasses is 20–25% [2, 3]. These results stimulated investigation of new promising crystal matrices with necessary spectroscopic properties and a relatively simple synthesis technique for lasers in this range. An example of such matrices is YAl3(BO3)4 (YAB) crystals, doped with ytterbium and erbium ((Er,Yb):YAB), belonging to the group of RM3(BO3)4 borates (R is Y, La–Lu; M is Al, Cr, Ga, Fe, Sc) [4]. They are characterized by high chemical and mechanical stability [5] and, in these parameters, they are more promising in comparison with other erbiumcontaining media [6, 7]. The purpose of this study is to optimize the procedures of growth and characterization of these crystals.
tion in the pseudoquaternary YAl3(BO3)4–K2Mo3O10– B2O3–Y2O3 system [5]. Potassium trimolybdate was synthesized according to the reaction K2Mo3O10 = K2MoO4 + 2MoO3. In turn, K2MoO4 and åÓé3 were obtained by annealing K2MoO4 · 10H2O and H2MoO4 at 500°ë for 24 h. An agent was considered completely dehydrated if its weight did not decrease over several hours. The other components, except for B2O3, were preliminarily calcinated for 24 h at temperatures lower than their melting points by 100–200°ë. Boric anhydride was separately melted into a platinum crucible to prevent ejection of charge due to its tendency to
EXPERIMENTAL Crystallization of (Er,Yb):YAB was performed from multicomponent melts based on potassium trimolybdate. The rate of its evaporation from open crucibles during experiments is relatively low, as a result of which one can fix with sufficient accuracy flux saturation temperatures in plotting solubility curves and introduce corresponding corrections to small variations in flux concentration as a result of evaporation of individual components [8]. The initial charge contained (in wt %) Er2O3 (0.18), Yb2O3 (0.91), Y2O3 (5.51), Al2O3 (7.51), B2O3 (13.09), and K2Mo3O10 (72.80); i.e., its composition corresponded to the r
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