Search

By conventional melt‐quenching techniques, a series of Dy3+‐doped (0.1 to 1.0 wt%) Ga5Ge20Sb15S60 bulk glasses were fabricated and their potential for developing mid‐infrared fiber laser beyond 4 μm were evaluated, in which the optimal Dy3+ doping concentration was found to be 0.3 wt% and the largest laser quality factor value (σe × τmea = 2.62 × 10−23 cm2 s) among all of the Dy3+‐doped chalcogenide glass was obtained. On this basis, through using the chemical purification methods with chlorine gas combined with the dynamic distillation process, the high‐purity GGSS glasses with low O–H and S–H absorptions were successfully fabricated, which was confirmed by the optimized mid‐infrared linear transmittance and improved fluorescent lifetimes of Dy3+: 6H13/2, 6H11/2 levels. Furthermore, for the first time to the best of our knowledge, the Dy3+‐doped, single‐mode, and double‐cladding chalcogenide fibers with the core/cladding ratios of 125:60:11 and 125:66:11.5 were achieved by a multistage rod‐in‐tube fiber drawing process and extrusion methods, respectively. The GeS2‐based fiber exhibits excellent transmission performance at 1.0‐5.0 μm: 3.0 dB/m at 2.9 μm (O–H), 2.4 dB/m at 4.1 μm (S–H). Combining the advantages of high‐purity, high doping concentration and single‐mode double‐cladding structure, the optimized active fiber should be an ideal efficient and low‐threshold medium toward mid‐infrared fiber laser beyond 4 μm. [ABSTRACT FROM AUTHOR]

Abstract: 0.2wt.% Dy3+-doped and 0.2wt.% Dy3+, 0.5wt.% Tm3+-codoped (100-x)GeS2 ·xIn2S3 (x=5,10,15,20,25) chalcogenide glasses were prepared. Their spectroscopic properties were analyzed based on absorption (ranges from 500 to 3000nm) and emission (ranges from 1000 to 4700nm) measurements. The Judd–Ofelt strength parameters Ωt (t =2, 4, 6) and the spectroscopy parameters Arad , β and τrad were calculated, and the σemi of the 1330, 2930 and 4320nm fluorescences were estimated. These Dy3+-doped and Dy3+, Tm3+-codoped Ge–In–S chalcogenide glasses are valuable materials for using in 1.3μm fiber-amplifiers and 2–5μm mid-infrared laser devices. [Copyright &y& Elsevier]

Yb3+/Ho3+ codoped and Yb3+/Er3+/Ho3+ tridoped TeO 2 –BaF 2 –LaF 3 –La 2 O 3 (TBLL) fluorotellurite glasses with low OH− absorption (0.026 cm-1), high glass transition temperature (434 °C) and low phonon energy (784 cm-1) were prepared. Their mid-infrared fluorescence properties and related energy transfer (ET) mechanism were studied under 980 nm excitation. A strong emission at 2.85 μm was realized in Yb3+/Ho3+ codoped tellurite glass, which was attributed to the high-efficiency ET from Yb3+ ions to Ho3+, and the ET efficiency was 91.1%. Further introduction of Er3+ ions induced stronger 2.85 μm emission, and the ET efficiency was improved to 96.2%, ascribed to the establishment of more ET channels and Er3+ ions playing the role of ET bridge between Yb3+ and Ho3+ ions. These results indicate that the Yb3+/Er3+/Ho3+ tridoped tellurite glass could be a hopeful gain medium material for the ∼3 μm fiber laser. [ABSTRACT FROM AUTHOR]

The 2.85 μm band has garnered significant attention for its wide range of applications in the mid-infrared region, and Ho3+ doped fluorotellurite fiber shows great promise as a gain medium for the 2.85 μm fiber laser. To achieve efficient population inversion for Ho3+ ions at 2.85 μm, Ho3+/Nd3+ co-doped fluorotellurite glasses with low hydroxyl were synthesized. The deactivation effect of Nd3+ ions to Ho3+: 5I 7 levels was investigated through emission spectra and lifetime decay curves under 890 nm excitation. The results show that Nd3+ ions can effectively quench the Ho3+: 2.05 μm emission and help the Ho3+: 5I 6 → 5I 7 transition to overcome the bottleneck of particle population inversion. Ultimately, the particle population inversion corresponding to 2.85 μm luminescence was realized in the Ho3+/Nd3+ co-doped fluorotellurite glass, and indicates that a maximum of 1.64 W laser at 2.85 μm with a slope efficiency of 8.72 % can be realized under 890 nm pump by numerical simulations. • Achieved low hydroxyl absorption in fluorotellurite glass. • Overcoming the population inversion bottleneck of the Ho3+: 5I 6.→ 5I 7 transition • Energy transfer mechanisms between Ho3+ and Nd3+ ions are discussed. • One-watt mid-infrared laser achieved theoretically in Ho3+/Nd3+ co-doped glass. [ABSTRACT FROM AUTHOR]

Fe:Co:ZnSe nanocrystals with different co-doping ratios of Fe2+/Co2+ ions were fabricated by hydrothermal synthesis. The facile method used in the present work avoids the mid-infrared quench effect induced by the organic molecular introduced in the past preparation process. These nanocrystals are spherical in shape and exhibit a cubic sphalerite structure with an average grain size of about 15 nm. Through the energy conversion between Co2+ and Fe2+ ions, mid-infrared fluorescences at 3.3 μm and 4.4 μm were detected under 1550 nm laser excitation at room temperature. The fluorescence band of 4.4 μm in the Fe:Co:ZnSe nanocrystals is thought to be an overlapping emission involving the peak centered at 4648 nm corresponding to the Co2+:4T 1 (F) → 4T 2 (F) energy transition and the peak centered at 4273 nm corresponding to Fe2+:5T 2 (D) → 5E (D) energy transition. These high-quality optically active nanomaterials show potential applications in mid-infrared devices such as composite fiber-amplifiers and lasers materials. • A serial Fe:Co:ZnSe nanocrystals were synthesized via hydrothermal method without organic ligand. • The emission at 4273 nm was detected in the Fe:Co:ZnSe nanocrystals at room temperature. • The 0.6 mol % Fe 3 mol % Co: ZnSe nanocrystals exhibit the strongest fluorescence. [ABSTRACT FROM AUTHOR]