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Phosphotellurite glass and glass-ceramics with high TeO <sub/>2</sub> content: thermal, structural and optical properties
摘要： Phosphotellurite based glasses have interesting features such as low characteristic temperatures, large glass forming ability, high thermal stability against crystallization and broad transparency window from ultraviolet (UV) to near-infrared (NIR), which makes them promising materials for photonic applications. In this work, phosphotellurite binary glasses, having composition (100 – x) TeO2–x Ba(PO3)2 with x varying from 1 to 20 mol %, were synthesized by the conventional melt-quenching method in covered gold crucibles under air. Optical, physical and structural properties of the new glass samples were investigated by differential scanning calorimetry, X-rays diffraction, Raman spectroscopy, transmission electron microscopy, linear optical absorption from UV to NIR, IR transmittance, and optical limiting experiments. Transparent glass-ceramics in the visible range were obtained for phosphotellurite samples containing 2, 4 and 6 mol % of Ba(PO3)2 and the phase crystallization was investigated through Rietveld analysis and transmission electron microscopy. The incorporation of Ba(PO3)2 into the TeO2 network drastically increases the thermal stability against devitrification and helps to shift the infrared multiphonon absorption edge to longer wavelengths. Nonlinear measurements performed with a picosecond laser at 532 nm indicate large effective nonlinear absorption coefficients for all samples. In summary, the dependence of the spectroscopic properties on the samples’ compositions revealed a promising transparent glass and glass-ceramics for photonic applications.
关键词： transparent glass-ceramics,phosphotellurite glass,optical properties,nonlinear optical response
更新于2025-11-14 17:03:37
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A novel Nd <sup>3+</sup> -doped MgO-Al <sub/>2</sub> O <sub/>3</sub> -SiO <sub/>2</sub> -based transparent glass-ceramics: towards excellent fluorescence properties
摘要： Generally, glass-ceramics have superior properties compared to their parent glasses. Here, we prepared a novel Nd3+-doped MgO-Al2O3-SiO2-based transparent glass-ceramics with excellent fluorescence properties. The effects of Nd2O3 content on the structure and properties of glass-ceramics were studied, aiming to provide a key guidance for preparing this transparent glass-ceramics. The results revealed that the glass stability increased originally and then decreased with increasing Nd2O3 content, so did the variation of wavenumbers in infrared spectra. And these glass-ceramics are mainly composed of cordierite with residual glassy phase. The three phenomenological intensity parameters (Ω2,4,6) and radiative properties were estimated by Judd-Ofelt theory, and the values of Ω2 first decreased and then increased with increasing Nd2O3 content. Three main emission peaks ascribed to the transitions from 4F3/2 to 4I9/2, 4I11/2, 4I13/2 at 898, 1057, 1330 nm were observed, respectively. The branching ratios for 4F3/2→4I11/2 transition increased as the Nd2O3 content raised, and the fluorescence lifetimes of the 4F3/2 level were found to increase first and then decrease with Nd2O3 content (from 181 to 726 μs). The excellent fluorescence properties indicate that this novel glass-ceramics can be used as a potential solid-state optical functional material for 1.06 μm laser emission.
关键词： MgO-Al2O3-SiO2,Judd-Ofelt theory,Nd3+-doped,Transparent glass-ceramics,Solid-state optical functional materials
更新于2025-09-23 15:22:29
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[IEEE 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Munich, Germany (2019.6.23-2019.6.27)] 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - A Novel Saturable Absorber: Transparent Glass-Ceramics Based on Co <sup>2+</sup> :Li(Al,Ga) <sub/>5</sub> O <sub/>8</sub> Spinel Nanocrystals
摘要： Cobalt ions (Co2+) embedded in tetrahedral (Td) sites are known for their intense absorption around 1.5 μm. Crystals such as spinel, MgAl2O4, doped with Co2+ ions in Td sites are recognized as excellent saturable absorbers (SAs) for eye-safe erbium lasers. Due to the relative difficulty to grow high-quality Co:MgAl2O4 crystals and fixed position of the Co2+ absorption band in spinel single-crystals, other Co2+-doped materials were proposed such as transparent glass-ceramics (GCs) and ceramics based on various spinels [1]. Transparent GCs offer a size-scalable synthesis method based on glass melting technology and variable spectroscopic properties as compared to crystals, and much higher laser induced damage threshold (LIDT) as compared to ceramics. GCs based on MgAl2O4 spinel nanocrystals modified by the addition of Ga3+ cations allow one to extend the SA properties until 1.7 μm [2]. In the present work, we describe the synthesis, structure, optical spectroscopy, nonlinear properties and passive Q-switching (PQS) performance of novel transparent GCs based on Co2+:Li(Al,Ga)5O8 nanocrystals. A lithium gallium aluminosilicate glass nucleated by TiO2 was doped with 0.1 mol% CoO. The GCs were produced by secondary heat-treatments at 680-850 oC for 6 h resulting in highly transparent, blue-colored samples, Fig. 1(a). The precipitation of nanosized spinel crystals was confirmed by XRD and TEM, Fig. 1(b,c), and Raman spectroscopy. The transparent GCs exhibited a broadband absorption band at 1.3-1.65 μm due to the 4A2(4F) → 4T1(4F) transition of Co2+ ions in Td sites in Li(Al,Ga)5O8 nanocrystals, Fig. 2(a). The saturable absoption of GC heat-treated at 750 oC for 6 h was studied by Z-scan method at 1540 nm using ns pulses. The saturation fluence FS is 0.50±0.05 J/cm2 and the LIDT exceeded 20 J/cm2, Fig. 2(b). This transparent GC was used to fabricate a SA for PQS of a compact diode-pumped Er,Yb:glass laser. This laser generated stable 7.4 ns / 1.34 mJ pulses at 1535 nm (peak power: 181 kW). The developed GC are promising as SAs for erbium lasers based on glass and crystalline materials (e.g., Er:YAG lasers emitting at 1617 nm and 1645 nm). This is because the broadband absorption of Co2+ ions in GCs is notably red-shifted as compared to Co:MgAl2O4 crystals which, in turn, is caused by the different spinel nanophase composition.
关键词： transparent glass-ceramics,Ga)5O8,Co2+:Li(Al,spinel nanocrystals,passive Q-switching,saturable absorber
更新于2025-09-11 14:15:04