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Er3+-doped fluoride glass modified by PbF2 is developed. Upon 980 nm laser-diode excitation, intense luminescence emission around 2.71 μm from the Er3+ 4I11/2 → 4I13/2 transition is observed. On the basis of the Judd–Ofelt theory, the intensity parameters and radiative properties are determined from the absorption and emission spectra. Compared with conventional Er3+-doped fluoride glass (Er:ZBLAN), the proposed glass possesses a large spontaneous emission probability (Arad, 29.76 s−1) and a high stimulated emission cross-section (σem) at 2.71 μm (1.25 × 10−20 cm2). In addition, fibers with high strength might be drawn from the glass preform owing to its good chemical stability; therefore, it may be useful for increasing the output power of mid-infrared lasers. The results indicate that the present glass can be a good candidate for mid-infrared fiber lasers.

In the current study, Er 3+ -doped fluorotellurite glasses modified by GaF 3 have been developed. High thermal stability and relatively low phonon energy are confirmed by differential thermal analysis and Raman spectroscopy, respectively. Upon 980 nm excitation, intense luminescence emission around 2.71 μm from the Er 3+ : 4 I 11/2 → 4 I 13/2 transition is observed in the glass. Based on the Judd-Ofelt theory, intensity parameters and radiative properties are determined from the absorption and emission spectra. The proposed glass possesses high thermal stability ( T g of ∼360 °C) and a large stimulated emission cross section, σ em , at 2.71 μm (1.617 × 10 −20 cm 2 ). The results indicate that it can be potentially applied in high-power mid-infrared fiber lasers.

Tb3+ ions doped optical materials have emerged as gain media for green fiber lasers. Dy3+ ions were proposed as a sensitizer of Tb3+ ions in glasses to increase the excitation efficiency, yet a systematic understanding of the impact of Dy3+ doping on spectroscopic and physiochemical properties of glasses remains lacking. Here, using Tb3+/Dy3+ doped fluoride glass as a model system, we reveal that Dy3+ doping not only enhances Tb3+ emission intensity, but also increases the thermal stability of fluoride glasses. Detailed spectroscopic characterizations indicate that co-doping Dy3+ ions boosts visible luminescence intensity of Tb3+ ions in fluoride glasses due to sensitization of Tb3+ by Dy3+ ions. Importantly, we deeply research the energy transfer process, ascertain several important factors affecting energy transfer efficiency and propose optimal doping concentrations of Tb3+ and Dy3+ ions for visible emission. We envisage that our finding provides a new perspective for the synthesis of Tb3+-doped fluoride glasses with enhanced thermal stability, and may be extended for the fabrication of Tb3+-activated optical fibers.

In this article, capillary electrophoresis was applied to investigate the chiral recognition mechanism for the enantioseparation on a well-known second-generation photodynamic therapy drug of benzoporphyrin derivative monoacid ring A, that is, verteporfin. In our previous study, cholate salts have been studied as the chiral selectors, which can realize baseline separation of the four verteporfin isomers. Aiming to reveal the chiral recognition mechanism, the separation effect of several kinds of chiral selectors was discussed. According to the results and references, the chiral separation mechanism of this system was concluded: the analytes selectively combine with the chiral micelles, that is, dynamic H-bonds interactions occur between the hydroxyl groups on the outer side of the cholate micelles and the ester/carboxy groups of the four isomers. In addition, the role of dimethyl formamide as an organic modifier was also researched, including reducing the effective mobility of the analytes and mobility of electroosmotic flow, and preventing them from adsorbing to the capillary wall and self-aggregating of verteporfin, which are pretty beneficial for separation. The method used in this article provides a direct and reliable solution to study the mechanism of chiral separation.

A series of Dy3+/Tm3+ single- and co-doped phosphate glasses with high moisture resistance and thermal stability was prepared by a conventional melt-quenching method. Under 365-nm ultraviolet (UV) light excitation, a white light with a chromatic coordinate of (0.3300, 0.3439), which is very close to the standard white light, could be obtained. The luminescence characteristics and energy transfer mechanism between the Dy3+ and Tm3+ ions were studied, and the fluorescence lifetime revealed the existence of the energy transfer processes. Furthermore, the Dy3+/Tm3+ co-activated glasses exhibited high moisture resistance, the emission peaks of 450, 480 and 572 nm remained at the original intensity of 99.2%, 99.9% and 99.9% of its original intensity after immersion in water for 120 h. At the same time, the luminescence intensity of the sample at 500 K can be maintained at a minimum of 85% of its intensity at room temperature, indicating the good thermal stability of the glasses. Overall, the prepared phosphate glasses have the potential to be applied in UV-based white-light-emitting diodes.

In this article, a simple capillary electrophoresis (CE) method was developed to analyze the glycated hemoglobin A1c (HbA1c) in light of the goal to monitor the long-term blood glucose concentration on diabetic patients, and it is the first time to report the binding constant of sodium tetraborate (Na2B4O7) and HbA1c in CE system. It is also found that the addition of Spermidine (Spd) can inhibit electroosmotic flow (EOF) well, thereby improving the resolution of the analytes. And a Spd concentration of a few mM is proper to provide perfect resolutions. Finally, the performance of the developed CE method was validated by analyzing actual blood specimens, of which the value of HbA1c was found to be close to the results of Sebia's CE method, showing an acceptable ability to separate hemoglobin forms. We expect this method will provide an inspiration to investigate hemoglobins (Hbs).

This paper studied the de-sensitization effect of Pr 3+ and Ho 3+ to Er 3+ :2.7 μm emission. Results show that both Pr 3+ and Ho 3+ are effective de-sensitizers, while great differences exist between them because of their non-phonon and phonon assisted energy transfer (ET) mechanisms. Ho 3+ depresses the 2.65 μm emission while Pr 3+ strengthens it greatly. ET coefficient indicates that Pr 3+ performs ten times higher 4 I 13/2 depletion ability than Ho 3+ . In Er/Ho glasses, about 1/10 energy back transfers to 4 I 13/2 level, which partially counterweights the depopulation of 4 I 13/2 level. The high absorption cross section of Ho 3+ is the reason for the larger 4 I 11/2 → 5 I 6 ET coefficient. Line strength and spontaneous radiation probability of 4 I 11/2 → 4 I 13/2 transition enhance moderately in E, E/H and E/P order, proving that the de-sensitizers promote the 2.7 μm transition positively. Long lifetime of Ho 3+ : 5 I 6 / 5 I 7 brings many problems, such as energy back transfer and strengthened upconversion, which also implies that the interactions of the particles obstruct the effective 4 I 11/2 → 4 I 13/2 transition correspondingly.

An Nd3+-doped fluorogallate glass with better thermal stability (Tg = 650.5 °C, ΔT = 190 °C), and lower linear thermal expansion coefficient (8.7 × 10−6/°C) compared with other commercialized laser glasses is reported in this paper. Judd–Ofelt theory is applied to the absorption spectrum of the glass to derive the intensity parameters (Ωt), which are in turn used to calculate the radiative properties of Nd3+ luminescent levels. The developed glass possesses the widest effective emission bandwidth (Δλeff = 49 nm) ever reported at around 1.07 μm, large gain bandwidth parameter (σem × Δλeff = 102.9 × 10−27 cm3), and high fluorescence quantum efficiency (η = 66%). These results indicate that this new kind of material is an interesting candidate for laser applications.

We selected two thermally matched silicate glasses with fair refractive index contrast and developed an asterisk-shaped all-solid microstructured optical fiber. The fiber presents a low, ultra-flat, and all-normal dispersion in a wide wavelength range, allowing for the generation of an octave-spanning coherent supercontinuum (SC) in a 20 dB dynamic range with 0.5 ps pump pulses at 1.55 μm. This result improves pump pulse duration that is only ∼100 fs, related to the broadband and highly coherent SC generation in fibers with all-normal dispersion. This enables broadband SC sources with all-fiber, high-power, and highly coherent properties.

We focus on the research of glasses for mid-infrared optical fiber and investigate the effects of different fluorides on the dehydration as well as structure, and heavy metal oxide modifiers Nb 2 O 5 , WO 3 and MoO 3 on the thermal stability as well as structure of tellurite glass of the main composition of TeO 2 –ZnO–Na 2 O–La 2 O 3 . Raman spectra indicate that Nb 2 O 5 , WO 3 and MoO 3 will mitigate the destructive effect of fluoride on TeO 4 entities. The fluorotellurite glass stability is directly related to the structure of TeO 4 groups. The hydroxyl absorption coefficient is 0.07 cm − 1 when 10% (mol) fluoride is introduced. We succeed to improve the thermal stability of fluorotellurite glasses by some composition modifications. Consequently, this glass is promising for optical fiber.

Lasing properties have been investigated for Yb(3+) doped glasses with similar emission cross sections (σ(emi)) and lifetime while possessing different Stark levels. Narrow Stark splitting of Yb(3+)-phosphate glass is responsible for severe heat generation, narrow emission band and much smaller σ(emi) at lasing wavelength, making Yb(3+)-phosphate glass unsuccessful to achieve laser output, whereas 1.166W cw laser was obtained in Yb(3+)-fluorophosphate (FP) glass with broader Stark splitting. Analysis on laser system levels reveals that under room temperature, Yb(3+) laser is quasi-3.13-level in phosphate glass and quasi-3.36-level in FP glass. These demonstrations suggest that unless the Stark splitting is enlarged, conventional Yb(3+)-phosphate glass is not a good gain medium for bulk Yb(3+)-laser.

Nanocrystalline La0.8Pb0.2FeO3 has been prepared by the sol-gel method. XRD patterns show that the nanocrystalline La0.8Pb0.2FeO3 is a perovskite phase with the orthorhombic structure and its mean crystallite size is about 19 nm. The influence of Pb ions which replaced the La ions on A-sites can be directly observed from the electrical and sensing properties to H2 gas. The conductance of La0.8Pb0.2FeO3-based sensor is considerably higher than that of LaFeO3-based sensor, and Pb-doping can enhance the sensitivity to H2 gas. An empirical relationship of \(R=K {C^{\alpha}_{H_{2}}}\) with α = 0.668 was obtained.

This research investigates the mechanism of the optical dispersive wave (DW) and proposes a scheme that can realize an efficient wavelength conversion. In an elaborately designed photonic crystal fiber, a readily available ytterbium laser operating at ∼1 μm can be transferred to the valuable 1.3 μm wavelength range. A low-order soliton is produced to concentrate the energy of the DW into the target wavelength range and improve the degree of coherence. The input chirp is demonstrated to be a factor that enhances the wavelength conversion efficiency. With a positive initial chirp, 76.6% of the pump energy in the fiber can be transferred into a spectral range between 1.24 and 1.4 μm. With the use of a grating compressor, it is possible to compress the generated coherent DW of several picoseconds into less than 90 fs.

In this paper, 80GeO2-8Ga2O3-10BaO-2Nb2O5-6PbO (in mol%) glass samples with different Tm2O3 concentrations (0, 0.5, 0.75, 1, 1.25, and 1.5 mol. %) were prepared by traditional melt-quenching method. According to the measurement of thermal properties of the host glass, the glass transition temperature is 596.7 °C and no crystallization peak is observed. Judd–Ofelt parameters Ωt (t = 2, 4, 6) and fluorescent lifetimes were obtained by Judd-Ofelt theory. The similar values of Judd–Ofelt parameters and the full-width at half-maximums of ∼1800 nm indicate the local environment of Tm3+ changes little with increment of Tm2O3 concentrations. Maximum stimulated emission cross-section of ∼1800 nm is 6.22 × 10−21 cm2 as calculated by Fuchtbauer–Ladenburg formula. Energy migration among Tm3+ ions was analyzed by the extended overlap integral method. The non-radiative transition rates between mainly energy levels of Tm3+ were calculated. Non-radiative transition rate of 3F4 energy level caused by OH was analyzed by rate equation and deduced by fitting the fluorescence decay curve.

Mid-infrared supercontinuum generation (SCG) is mostly studied in fluoride glass fibers in which long fibers and high power pump sources are needed. Taking advantages of high nonlinearity and transparency, chalcogenide glass is also applied for SCG in mid-infrared region, where specific strategy is needed to compensate large normal material dispersion. We investigate multimaterial fibers (MMFs) combined with fluoride and chalcogenide glasses for SCG. The high refraction contrast allows the zero dispersion point of the fiber to shift to below 2 μm without air holes. These two materials have similar glass transition temperatures and thermal expansion coefficients. They are possible to be drawn together. Both step-index MMFs and microstructured MMFs (MS-MMFs) are considered. The chromatic dispersions and supercontinuum spectra are studied. A 20 dB bandwidth of over one octave SCG with high coherence can be obtained from a 1 cm MS-MMF at 1.95 μm with a pumping peak power of 175 W. As the pump power increased, the spectrum can extend to 5 μm. In this scheme the fiber is so short that the high level of loss, which is the feature of MMFs, will not cause problems.

Zn0.97Co0.03O nanocrystalline powders were prepared by sol-gel method with a low annealing temperature of 450°C. The as-synthesized Zn0.97Co0.03O powders were paramagnetic. However, after compaction under a pressure of 94MPa, the Zn0.97Co0.03O pressed powders show a weak room-temperature ferromagnetism embedded in the paramagnetic background. The observed ferromagnetism is connected with compaction-induced defects at/near grain boundaries. Meanwhile, a room-temperature magnetoresistance ΔR∕R0 as high as −73.7% is observed in Zn0.97Co0.03O pressed powder sample.