Mei Yan,Ru-Ling Tang,Wei Xu,Wenlong Liu,Sheng-Ping Guo
Zirconium/hafnium fluorides have recently been recognized as potential nonlinear optical (NLO) materials with short ultraviolet (UV) cutoff edges, which is significant in laser science and industry. The synthesis of noncentrosymmetric (NCS) materials based on centrosymmetric (CS) compounds by an isovalent cation substitution-oriented design is an emerging strategy in the NLO territory. Here, two isostructural and novel fluorides, CaBaMF8 (M = Zr (1), Hf (2)), have been synthesized through the combination of alkaline earth metals, zirconium/hafnium, and fluorine elements. They feature zero-dimensional and CS structures composed by an isolated MF8 (M = Zr, Hf) dodecahedron and dissociative Ca2+ and Ba2+ cations, and they display short UV cutoff edges (<200 nm) as well. Two three-dimensional fluorides Li2CaMF8 (M = Zr (3), Hf (4)) are obtained by replacing Ba with alkali metal Li atom, which not only represent phase-matchable second-harmonic-generation activities (0.36, 0.30× KH2PO4 (KDP)) at 1064 nm but also maintain short UV cutoff edges with high reflectance. This work has largely enriched the family of NCS zirconium/hafnium fluorides reaching the short UV region.
Tm 3+ doped Bi 2 O 3 -GeO 2 -Na 2 O glass samples were synthesized by conventional melt-quenching method. The Raman spectra measurements showed the maximum phonon energy of prepared glass is 794 cm −1 , which is considerably lower than silicate glasses . Based on the measured absorption spectra , Judd-Ofelt intensity parameters, spontaneous radiative transition probabilities and radiative lifetimes were calculated to elucidate the radiative properties of Tm 3+ in the presented glass. Intense near infrared emission around ~2 μm was obtained under the pump of 808 nm laser diode . A large stimulated emission cross section (5.51 × 10 −21 cm 2 at 1851 nm) of Tm 3+ : 3 F 4 → 3 H 6 was achieved in the prepared bismuth germanate glass doped with 1 mol% Tm 2 O 3 . Besides, the energy transfer processes among Tm 3+ were analyzed using the extended overlap integral method. These results indicate that the presented glass is a promising candidate for ~2 μm laser applications.
Yan Sun,Xin Wang,Meisong Liao,Lili Hu,Malgorzata Guzik,Georges Boulon,Xia Li,Pei-Wen Kuan,Weiqing Gao,Tianxing Wang
In this work, we explore the effect of ionic field strength of modifiers (Li + , Na + , K + , Mg 2+ , Ca 2+ , Sr 2+ and Ba 2+ ) on room-temperature Stark splitting and spectroscopic properties of Yb 3+ ions in lead silicate glasses. Our measurements show that the ‘crystal-field’ parameter and asymmetry degree of Yb 3+ ion ligands are increased as a function of modifier field strength due to the corresponding higher electronegativity and bonding energy. Higher field strengths produce greater absorption σ a and emission σ e cross-sections, effective emission linewidth Δ λ eff and spontaneous emission probability A rad of Yb 3+ ions. We report a 57% enhancement on σ a , σ e and Δ λ eff by doubling the field strength of the modifier cations, implying Yb 3+ ion doped lead silicate glass with high field strength modifiers (Li + , Mg 2+ and Ca 2+ ) may be a promising candidate for efficient laser emission operation.
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