Search

Transparent, inorganic composite materials are of broad interest, from structural components in astronomical telescopes and mirror supports to solid-state lasers, smart window devices, and gravitational wave detectors. Despite great progress in material synthesis, it remains a standing challenge to fabricate such transparent glass composites with high crystallinity (HC-TGC). Here, we demonstrate the co-solidification of a mixture of melts with a stark contrast in crystallization habit as an approach for preparing HC-TGC materials. The melts used in this approach are selected so that glass formation and crystal precipitation occur simultaneously and synergistically, avoiding the formation of interfacial cracks, residual pores, and delamination effects. Using this method, various unusual hybridized HC-TGC materials such as oxychloride, oxybromide, and oxyiodide composite systems were fabricated in dense, bulk shapes. These materials exhibit intriguing optical properties and neutron response-ability. Using such HC-TGC materials, we develop a neutron detector and demonstrate the application for efficient neutron monitoring and even single neutron detection. We expect that these findings may help to bring about a generation of fully inorganic, transparent composites with synergistic combinations of conventionally incompatible materials. Transparent composites are significant for various applications. Here, the authors propose the co-solidification strategy of crystal and glass melts for preparing transparent glass composite with high crystallinity and apply for neutron detection. [ABSTRACT FROM AUTHOR]

Square-root topological insulators recently discovered are intriguing topological phases. They possess topological properties inherited from the squared Hamiltonian and exhibit double-band structures. The mechanism of the square root was generalized to 2n-root topological insulators, giving rise to more band gaps. In this study, we describe the experimental realization of one-dimensional 2n-root topological insulators in photonic waveguide arrays using the archetypical Su-Schrieffer-Heeger (SSH) model. Topological edge states with tunable numbers are clearly observed under visible light. In particular, we visualized the dynamic evolutions of the light propagation by varying the sample lengths, which further proved the localization and multiple numbers of edge states in 2n-root topological systems. The experiment, which involves constructing 2n-root topological photonic lattices in various geometric arrangements, provides a stable platform for studying topological states that exhibit a remarkable degree of flexibility and control. [ABSTRACT FROM AUTHOR]

In order to make full use of sunlight and broaden the response spectral range of photocatalysts, herein, we prepared α-Bi2O3-Bi4O7-BiO2 − x composite photocatalysts with near-infrared response by a one-step hydrothermal method for the first time using Bi(NO3)3·5H2O and NaBiO3·2H2O as raw materials. The results showed that the α-Bi2O3-Bi4O7-BiO2 − x composite photocatalyst achieved 99.5% removal efficiency of rhodamine B (RhB) within 180 min under visible light irradiation, which was much higher than that of binary materials (17.8% for Bi4O7-BiO2 − x, 79.3% for α-Bi2O3-Bi4O7, and 38.4% for α-Bi2O3-BiO2 − x), single compounds (α-Bi2O3 18.6%, Bi4O7 63.4%, and BiO2 − x 13.6%), the reaction kinetic constants were about 18, 3, and 24 times higher than those of α-Bi2O3, Bi4O7, and BiO2 − x. The degradation rates of α-Bi2O3-Bi4O7-BiO2 − x for RhB, TC-HCl, OTC-HCl, ketoprofen, SMZ, and 2,4-DCP within 180 min were 99.5%, 100%, 100%, 81.1%, 90.4%, and 87.1%. Meanwhile, α-Bi2O3-Bi4O7-BiO2 − x still showed efficient removal of RhB in river water, lake water, and sea water, and showed higher activity under solar irradiation. Additionally, experimental characterization demonstrated that the enhanced photocatalytic performance was due to oxygen vacancies’ effective participation in electron transport, which made it easier to separate electron–hole pairs. Due to the narrow band gap of BiO2 − x, α-Bi2O3-Bi4O7-BiO2 − x displayed the removal performance of RhB under near-infrared light irradiation. This research is conducive to resulting in useful applications for photocatalysts in various settings including natural waterways. [ABSTRACT FROM AUTHOR]

Additive manufacturing (AM), which is also known as three-dimensional (3D) printing, uses computer-aided design to build objects layer by layer. Here, we focus on the recent progress in the development of techniques for 3D printing of glass, an important optoelectronic material, including fused deposition modeling, selective laser sintering/melting, stereolithography (SLA) and direct ink writing. We compare these 3D printing methods and analyze their benefits and problems for the manufacturing of functional glass objects. In addition, we discuss the technological principles of 3D glass printing and applications of 3D printed glass objects. This review is finalized by a summary of the current achievements and perspectives for the future development of the 3D glass printing technique. [ABSTRACT FROM AUTHOR]

The development of high-power white light-emitting diodes demands highly efficient and stable all-inorganic color converters. In this respect, phosphor-glass/ceramic composites show great promise as they could combine the merits of high quantum efficiency of phosphors and high chemical and thermal stabilities of glass/ceramic matrices. However, strong interfacial reaction between phosphors and matrices at high temperature results in quantum efficiency loss of the embedded phosphors, and traditional solutions rely on high-pressure consolidation techniques. Here we report the intrinsic inhibition of interfacial reaction by using silica glass rather than multicomponent glasses as the matrix. The embedment of phosphors is achieved via a pressureless sintering method, rendering these color-tunable phosphor-glass composites not only accessible to three-dimensional printing technique, but also highly efficient (internal quantum efficiency >90.0%), thermally stable at 1200 °C and hydrothermally stable at 200 °C. Our results provide a facile and general strategy for developing all-inorganic functional composites. Phosphor-glass/ceramic composites are attractive for high-power white light-emitting diodes, but interfacial reaction leads to loss of quantum efficiency. Here the authors report a reduction sintering method for embedment of phosphors into silica glass with limited interfacial reaction. [ABSTRACT FROM AUTHOR]

The three-dimensional (3D) patterning of semiconductors is potentially important for exploring new functionalities and applications in optoelectronics1,2. Here, we show that it is possible to write on demand 3D patterns of perovskite quantum dots (QDs) inside a transparent glass material using a femtosecond laser. By utilizing the inherent ionic nature and low formation energy of perovskite, highly luminescent CsPbBr3 QDs can be reversibly fabricated in situ and decomposed through femtosecond laser irradiation and thermal annealing. This pattern of writing and erasing can be repeated for many cycles, and the luminescent QDs are well protected by the inorganic glass matrix, resulting in stable perovskite QDs with potential applications such as high-capacity optical data storage, information encryption and 3D artwork. Luminescent CsPbBr3 quantum dots can be written into glass using femtosecond laser pulses and thermal annealing, and erased by further femtosecond laser irradiation. The resulting quantum dot patterns could prove useful for data storage, decoration or security purposes. [ABSTRACT FROM AUTHOR]

In this study, a series of Er3+/Yb3+ co-doped Ca–Mg–Si glasses were prepared via the containerless processing. Phase composition and luminescent properties of the prepared materials were investigated through XRD and spectrometry, and bioactivity, biocompatibility and cytotoxicity were evaluated. The XRD patterns indicated that akermanite (AKT) ceramic powders were completely transformed into the glassy phase (AKT-G, EYA) through the containerless processing, which exhibit upconversion luminescence, and the luminescence intensity increased with the increase of the doping amount of Er3+ and Yb3+. High amount of Yb3+ doping and existence of Ca2+ in glasses resulted in more intensive red-light emission. The SEM observation, combined with EDS analysis, and cell culture experiments showed that the as-prepared glasses were nontoxic, biocompatible and bioactive. All these results demonstrated that the containerless processing is a facile method for preparing homogeneous luminescent bioactive glasses. Furthermore, this luminescent Ca–Mg–Si glasses may be used as bone implant materials to study the in vivo distribution of degradation products of bone implants, which may be of great significance for the development and clinical application of new bone grafting materials. [ABSTRACT FROM AUTHOR]

Broadband and tunable near-infrared (NIR) emission of Ni2+ doped glass–ceramics (GCs) is highly attractive due to their potential to address the challenge of broadband optical amplification in the optical communication band. However, optical activity of Ni2+ in different glass matrix as well as nucleation and crystallization processes in relevant glasses have not been understood fully. Here, broadband NIR photoluminescence was realized through precipitation of LiGa5O8:Ni2+ nanocrystals (NCs) within an alkali gallium-silicate glass matrix by melt-quenching and successive heat treatment. Upon exciting by a 980 nm laser diode, we observed NIR photoluminescence band centered at ~ 1310 nm with full width at half maximum of wider than 300 nm, which was originated from 3T2g(3F) → 3A2g(3F) electronic transition of octahedral coordinated Ni2+ in LiGa5O8 NCs embedded in the GCs. Controlled precipitation of NCs, LiGa5O8:Ni2+ and Ga2O3:Ni2+ were achieved by tailoring the composition of alkali gallium-silicate glass matrix. ab initio molecular dynamics simulation was carried out to clarify the formation of nanophases in the glass system. We confirmed that optical properties of transparent GCs containing Ni2+ NCs can be realized by changing molar percentages of Ga2O3. Our results offer a new insight into the precipitation of NCs in oxide glasses and Ni2+ doped GCs, which may be applicable in the photonic fields, such as optical amplifier and laser. [ABSTRACT FROM AUTHOR]

Greater enhancement in upconversion (UC) luminescence was observed in the glass-ceramics (GCs) containing CaF2:Yb3+, Er3+ nanocrystals (NCs) compared with whose doped with LaF3:Yb3+, Er3+ NCs prepared by conventional melt-quenching technique followed by successive heat treatment. Our joint experimental and theoretical studies suggest the lager enhancement of UC emission in CaF2-GCs rather than of LaF3-GCs is associated with the difference in the microstructures, the crystal size, the local coordination environment around rare earth (RE) ions as well as the structural rigidity in the silicate region of the GCs. In addition, it was found that a more symmetric ligand field around RE ions in a smaller size crystal which distributed more homogeneously within the highest ordering silicate region favors stronger UC emission by facilitating the energy transfer process and minimizing the rate of non-radiative relaxation process. Our results may enrich our understanding about UC process in oxyfluoride GCs and provide a general picture for the photophysical processes that contribute to the UC in similar GCs systems. [ABSTRACT FROM AUTHOR]

Alkaline earth orthosilicates M2SiO4 (M = Ba, Sr and Ca) phosphors doped with Mn5+ ions have been prepared by the conventional solid-state reaction method. The crystal structures were verified by X-ray diffraction. By varying the host composition from Ba to Ca, the position shifting of photoluminescence emission bands corresponding to the 1E → 3A2 transition are induced by the increasing angular distortion and covalence. The nonradiative energy transfer becomes a dominant role in the photoluminescence process with substituting Ba2+ sites for smaller cations. The structural evolution and relevant luminescence mechanisms in (Ba1−xCax)2SiO4 phosphors also have been investigated in detail. It reveals that the chemical composition modification and structural variation can be an efficient approach to optimize the photoluminescence behaviors. [ABSTRACT FROM AUTHOR]

The development of doped photonic glass is of fundamental importance for various applications, including telecommunication, lasers, and photovoltaics. Despite the great advances in doping techniques, a long-standing barrier remains concerning how to gain better control over the properties of active dopants in disordered systems. Here, we provide a brief overview of recent progress on the engineering of the chemical environment and chemical state of dopants in glass by tuning the topological features, including sublattices and packing manner of the network. The methods allow us to finely tune the chemical state of active dopants over a wide range of length scales, from dispersed ions to aggregated clusters to nanoparticles, and also offer new opportunities to engineer the local crystal field around active dopants. This inherent structure-based strategy leads to intriguing optical phenomena such as tunable luminescence and notable enhancements in radiative transition probability. [ABSTRACT FROM PUBLISHER]

Improving upconversion luminescence efficiency of lanthanide-doped nanocrystals is always a hot topic for scientists because of its very important application in photonics, photovoltaics, biological imaging, security printing, and therapeutics. Two-color laser field has shown to be a well-established strategy to further improve the upconversion luminescence efficiency. Here, we first propose a two-color laser field combining the 850 and 980 nm lasers to improve the green and red upconversion luminescence efficiency in Er-doped NaYF nanocrystals. In this work, an important advantage for our strategy is that the population is directly pumped to the radiation energy level of the upconversion luminescence by a cooperation excitation process, but not the spontaneous decay from other higher energy levels, and so the higher luminescence enhancement efficiency can be obtained. These studies also provide a clear physical picture for the physical control mechanism of the upconversion luminescence efficiency improvement, which can pave a way to properly design the laser fields in the future study of upconversion luminescence generation and control. [ABSTRACT FROM AUTHOR]

Nanofibers functionalized by semiconductor nanocrystals are drawing increasing interest, due to their widespread applications in the fields of new energy development, environment protection and chemical sensing, etc. Herein, we demonstrate a simple approach to prepare CuO/SiO nanocomposite materials. The flexible SiO nanofibers were prepared via the sol-gel electrospinning techniques. CuO nanocrystals were grafted on the surface of SiO nanofibers by simply soaking and post-calcination. Micromorphology, structure and mechanical strength of SiO/CuO nanocomposite fibers were investigated by SEM, TEM and stress-strain test. Photocatalytic water purification ability of SiO/CuO nanofibers was evaluated by employing rhodamine B as a model pollutant. Our results indicated that the SiO/CuO nanofibers were flexible, thermally resistant and photocatalytic reactive, which promise the potential application in environmental remediation. [ABSTRACT FROM AUTHOR]

Ce, Yb co-doped YAlO films were prepared by pulse laser deposition. X-ray diffraction, X-ray photoelectron spectroscopy, photoluminescence spectra were used to characterize their structural and luminescent properties. Near-infrared quantum cutting from the films was observed via a cooperative energy transfer from Ce to Yb ions. The high quantum efficiency of the films implies that Ce,Yb co-doped YAlO films have potential application by tuning the solar spectrum to enhance the efficiency of silicon solar cells. [ABSTRACT FROM AUTHOR]

Folic acid-conjugated luminescent nanomaterials have long been widely used in targeted bioimaging, often simultaneously acting as vehicles for drug delivery. They often require, however, intense light sources for photoexcitation, and this often results in photobleaching, strong luminescence background, and strong light scattering. This article describes the preparation of nanoparticles (NPs) of the type ZnGaSnO doped with Cr(III) ions and surface-modified with folic acid. The functionalization of the NPs was monitored via measurement of zeta potentials, FTIR spectra and thermogravimetry. Cell viability and biocompatibility were tested using the MTT kit. The NPs have a size of 220 nm and were characterized by dynamic X-ray diffraction, light scattering, field emission scanning electron microscopy and high-resolution transmission electron microscopy. After annealing the NPs for 10 min at 300 °C and irradiating them with 254 nm light for 10 min, they display deep red emission that persists for up to 10 h. The NPs are easily dispersed, small-sized, and crystalline. In our perception, the new material with its long decay time offers quite novel features in terms of targeted optical imaging in providing high resolution, weak disturbance by background luminescence, and the absence of light scattering. They were successfully applied to image MCF-7 and A549 cells. [Figure not available: see fulltext.] [ABSTRACT FROM AUTHOR]

In this paper, the effect of the irradiation pulse number on the morphology of the near-wavelength ripples perpendicular to the laser polarization was investigated. The results show that the ripple spacing first fast decreases with the increased irradiation pulse number and finally reaches a stable value. The change of ripple morphology with different incidence angles was also studied. The ripples are found keeping always perpendicular to the laser polarization and have respective ripple spacings of 650, 480 and 390 nm upon the laser irradiation with pulse number N = 16 and fluence of 1.33 J/cm at the incidence angles of 0°, 30° and 60°. The change of the ripple spacing with different excitation levels was also studied. The theory for interference of the incident wave with the surface plasmon polariton wave (SPP) and the Sipe-Drude theory are both employed to analyze the experimental results. Detailed calculations show that the Sipe-Drude theory works better for explaining the main features of the ripples on silicon wafer surface. We suggest that the interaction of the incident wave with some form of surface electromagnetic wave except SPP is most possibly responsible for the ripple formation on silicon surface. [ABSTRACT FROM AUTHOR]

Two-dimensional (2D) complex nanostructures on the surface of ZnO crystal are fabricated by the interference of three 800 nm fs laser beams. The 2D nanostructures exhibit a great enhancement of UV emission excited by infrared fs laser with central wavelengths ranging from 1,200 nm to 2,000 nm. We propose that the defect states in the band gap of 2D nanostructures induced by 800 nm fs laser ablation cause the great enhancement of UV emission. We make theoretical calculations and explain well with the experimental results. [ABSTRACT FROM AUTHOR]

CaNbO:Sm films were prepared on quartz glass and α-AlO(001) substrates by pulsed laser deposition. The structural, morphological, and optical properties of the CaNbO:Sm films were characterized by X-ray diffraction (XRD), atomic force microscopy (AFM), emission-scan electron microscopy (SEM), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS) and photoluminescence spectroscopy (PL) measurements. The results show that the structure and properties of CaNbO:Sm films were dependent on substrates. The CaNbO:Sm films on AlO(0001) substrate have better crystallinity. The full-width at half-maximum (FWHM) of (131) peak are 0.45 and 0.32 for the CaNbO:Sm film on glass and AlO(001), respectively. The crystallite size of CaNbO:Sm films grown on glass and AlO(001) was about 8.22 and 9.98 nm, respectively. The oxidation state of the Sm element on the films was Sm state. The photoluminescence (PL) spectra were measured at room temperature, the CaNbO:Sm films on AlO(001) substrate have a better PL intensity, the identified emission bands were by the intra 4f transitions of Sm from the excited level to the lower levels at 567 nm for G→H transition, at 609 nm for G→H transition, and at 657 nm for G→H transition. [ABSTRACT FROM AUTHOR]

We report the fabrication of cross-linked micro/nanopatterns on ZnO by adjusting the femtosecond-laser polarizations of four-beam interference. The micro/nanopatterns are composed of two types of patterns with vertically oriented and horizontally oriented ripples, respectively. The relative locations, ablation depths and the nanoripple distributions of the two patterns can be manipulated by adjusting the laser polarizations. Theoretical calculations of the interference patterns indicate clearly that the micropatterns are determined by the interferential intensity patterns, while the nanopatterns depend on the interferential polarization patterns. The micro/nanopatterns have potential applications in micro-optical polarization diffraction elements by virtue of femtosecond-laser-induced anisotropy. [ABSTRACT FROM AUTHOR]

We report on the absorption, static, and transient luminescence spectra of Sm3+-doped glasses. The dependences between absorption and emission cross sections as well as between luminescence quantum efficiencies and Sm3+ doping concentration are examined. The large stimulated absorption cross section and emission cross section combined with the long fluorescent lifetime make phosphate glasses doped with Sm3+ promising material for visible fiber lasers. Moreover, ΔT(Tx − Tg) of these glasses is about 290 °C, which guarantees their thermal stability against crystallization during the fiber drawing process. [ABSTRACT FROM PUBLISHER]

We report on the synthesis of nanocrystalline zirconia in liquid using femtosecond laser ablation. Nanocrystalline cubic zirconia has been prepared by femtosecond laser ablation of zirconium in ammonia, while nanocrystalline tetragonal and monoclinic zirconia was synthesized in water. The physical and chemical mechanisms of the formation of nanocrystalline metastable zirconia are discussed. The intrinsic properties of femtosecond laser ablation in liquid and OH may be responsible for the synthesis of cubic zirconia. It is suggested that the femtosecond laser pulse can create higher temperature and pressure conditions at a localized area in the liquid than the nanosecond laser pulse and the cooling is also faster in the femtosecond laser ablation process, which determined the difference between the products synthesized with femtosecond and nanosecond-pulsed laser ablation. [ABSTRACT FROM AUTHOR]

An experimental and numerical study of the NO formation and reduction process in a designed coal combustion furnace under both traditional air atmosphere and O/CO atmosphere was conducted, in an attempt to explore the chemistry mechanism of the experimentally observed NO suppression under high CO concentration atmospheres. A simplified' chemically oriented' approach, computational fluid dynamics (CFD)-chemical kinetics modeling method, was validated and used to model the experimental process. The high CO concentration's chemical effect on NO reduction has been studied, and the differences in NO reaction behaviors between O/CO atmosphere and air atmosphere were analyzed by detailed chemical kinetic model. On the basis of investigations through elementary chemical reactions, it can be concluded that high CO concentration plays an important role on NO conversion process during oxy-fuel combustion. Moreover, the dominant reaction steps and the most important reactions for NO conversion under different atmospheres were discussed. Under O/CO atmosphere, the main active sequence for NO reaction includes: NO→N→N, and the main active path for NO reaction under air atmosphere is through N→N→NO. [ABSTRACT FROM AUTHOR]

Uncertainty analysis was used to investigate the precision property of detailed chemical kinetic models. A general-purpose algorithm for assessing and evaluating the impact of uncertainties in chemical kinetic models is presented. The method was also validated through analysis of different kinetic mechanisms applied in the process of modeling NO emission in methane flame. The algorithm, which provided a basis for further studies, was more efficient and general compared with other methods. [ABSTRACT FROM AUTHOR]

Cr3+-doped LiInSiO4 phosphors were prepared by a solid-state reaction method. X-ray diffraction measurement was carried out for crystalline phase identification. Absorption, photoluminescence, excitation, and time-resolved spectra were measured to investigate the optical properties of the phosphors. Two broadband near-infrared emissions centered at 920 and 1172 nm were observed. Time-resolved spectra show that the emission at 1172 nm decays more quickly than the emission at 920 nm. The electron spin resonance spectra exhibit a broad resonance signal at g = 1.96 because of exchange-coupled Cr3+ pairs. The value of Dq/B for low and intermediate crystal fields was evaluated. We suggest that Cr3+ incorporated into different octahedral sites of the crystal is responsible for the different near-infrared luminescence. [ABSTRACT FROM AUTHOR]

In this article, the chemical and structural changes inside soda-lime glasses induced by femtosecond (fs) laser pulsing have been reported, based on transmission electron microscopy and electron energy loss spectroscopy studies. Under fs-laser interaction, Na-rich phases are formed, and Na nanoparticles are also precipitated around the Na-rich phases. These findings demonstrate how powerful and efficient the fs-laser pulsing and interaction can be in making novel microstructures in soda-lime silicate glass, and they bridge the gap between the macroscale property changes and nanometer-scale structures. [ABSTRACT FROM AUTHOR]

We report on photoreduction of Ag+ in aluminoborate glasses induced by irradiation of a femtosecond laser. Novel fluorescence was observed in the femtosecond laser irradiated glass when excited by a 365 nm ultraviolet lamp. Optical absorption, emission, and electron spin resonance spectra of the glass samples demonstrated that after the laser irradiation, portions of silver ions near the focused part of the laser beam inside the glass were reduced to silver atoms, which resulted in the formation of the characteristic fluorescence. The observed phenomenon may have promising applications in the fabrication of functional optical devices. [ABSTRACT FROM AUTHOR]

Quantification of nanoparticle-molecule interaction at a single-molecule level remains a daunting challenge, mainly due to ultra-weak emission from single molecules and the perturbation of the local environment. Here we report the rational design of an intraparticle-surface energy transfer (i-SET) process, analogous to high doping concentration-induced surface quenching effects, to realize single-molecule sensing by nanoparticle probes. This design, based on a Tb3+-activator-rich core-shell upconversion nanoparticle, enables a much-improved spectral response to fluorescent molecules at single-molecule levels through enhanced non-radiative energy transfer with a rate over an order of magnitude faster than conventional counterparts. We demonstrate a quantitative analysis of spectral changes of one to four fluorophores tethered on a single nanoparticle through i-SET spectroscopy. Our results provide opportunities to identify photoreaction kinetics at single-molecule levels and provide direct information for understanding behaviors of individual molecules with unprecedented sensitivity. Single-molecule sensing is very challenging due to weak emitted signals and environmental interference. Here the authors design a method (i-SET) for single molecule sensing with core-shell upconverting nanoparticles, which relies on signal enhancement by the activator-rich probes to quantify fluorophores attached to a single nanoparticle. [ABSTRACT FROM AUTHOR]

An amendment to this paper has been published and can be accessed via a link at the top of the paper. [ABSTRACT FROM AUTHOR]

Bi-doped (60-x)GeO2-xSiO2-15B2O3-20MgO-5Al2O3-0.5Bi2O3 (x = 0, 5, 10, 15,20, 25 mol%)glasses were prepared by a conventional melt-quenching process. A broad near-infrared (NIR) photoluminescence (PL) band from Bi centers centered around 1100 nm with a large full-width-at-half-maximum value (~ 195 nm) was observed under excitation at 700 nm. Along with the increase of SiO2 concentration, the NIR PL intensity and the quantum yield (44.1-51.2%) increase first and then decrease, and the PL lifetime increases from 409 to 464 µs. The spectroscopic properties can be interpreted in terms of Bi centers with different valence states, which were confirmed by two-dimension photoluminescence excitation map spectra. The dependence of optical properties on SiO2 concentration is mainly attributed to the change of the optical basicity among different samples. This Bi-doped B2O3-GeO2-SiO2 glass could find potential application in fiber amplifier and laser due to the efficient and tunable broad NIR luminescence. [ABSTRACT FROM AUTHOR]

Optical modulation is a crucial operation in photonics for network data processing with the aim to overcome information bottleneck in terms of speed, energy consumption, dispersion and cross-talking from conventional electronic interconnection approach. However, due to the weak interactions between photons, a facile physical approach is required to efficiently manipulate photon-photon interactions. Herein, we demonstrate that transparent glass ceramics containing LaF3: Tm3+ (Er3+) nanocrystals can enable fast-slow optical modulation of blue/green up-conversion fluorescence upon two-step excitation of two-wavelengths at telecom windows (0.8-1.8 μm). We show an optical modulation of more than 1500% (800%) of the green (blue) up-conversion fluorescence intensity, and fast response of 280 μs (367 μs) as well as slow response of 5.82 ms (618 μs) in the green (blue) up-conversion fluorescence signal, respectively. The success of manipulating laser at telecom windows for fast-slow optical modulation from rear-earth single-doped glass ceramics may find application in all-optical fiber telecommunication areas. [ABSTRACT FROM AUTHOR]

A glass-ceramic optical fiber containing Ba2TiSi2O8 nanocrystals fabricated using a novel combination of the melt-in-tube method and successive heat treatment is reported for the first time. For the melt-in-tube method, fibers act as a precursor at the drawing temperature for which the cladding glass is softened while the core glass is melted. It is demonstrated experimentally that following heat treatment, Ba2TiSi2O8 nanocrystals with diameters below 10 nm are evenly distributed throughout the fiber core. Comparing to the conventional rod-in-tube method, the melt-in-tube method is superior in terms of controllability of crystallization to allow for the fabrication of low loss glass-ceramic fibers. When irradiated using a 1030 nm femtosecond laser, an enhanced green emission at a wavelength of 515 nm is observed in the glass-ceramic fiber, which demonstrates second harmonic generation of a laser action in the fabricated glass-ceramic fibers. Therefore, this new glass-ceramic fiber not only provides a highly promising development for frequency conversion of lasers in all optical fiber based networks, but the melt-in-tube fabrication method also offers excellent opportunities for fabricating a wide range of novel glass-ceramic optical fibers for multiple future applications including fiber telecommunications and lasers. [ABSTRACT FROM AUTHOR]

Rare earth doped mid-infrared (MIR) fluorescent sources have been widely investigated due to their various potential applications in the fields of communication, chemical detecting, medical surgery and so forth. However, with emission wavelength extended to MIR, multiphonon relaxation process that strongly quenched the MIR emission is one of the greatest challenges for such practical applications. In our design, we have described a controllable gas-aided annealing strategy to modulate the phase, crystal size, morphology and fluorescent performance of a material simultaneously. Uniform and monodispersed Er3+-doped La2O2S and La2O2SO4 nanocrystals with a similar lattice structure, crystallinity, diameter and morphology have been introduced to investigate the impact of multiphonon relaxation on luminescence performance. Detailed spectroscopic evolutions in the region of MIR, near-infrared (NIR), visible upconversion (UC) and their corresponding decay times provide insight investigation into the fluorescent mechanism caused by multiphonon relaxation. A possible energy transfer model has also been established. Our results present direct observation and mechanistic investigation of fluorescent evolution in multiphonon relaxation process, which is conductive to design MIR fluorescent materials in the future. To the best of our knowledge, it is the first investigation on MIR fluorescent performance of La2O2S nanocrystals, which may find various applications in many photoelectronic fields. [ABSTRACT FROM AUTHOR]

High-yielded Bi2Te3 hexagonal nanoplates were fabricated via a facile solvothermal method with the assistance of poly (vinyl pyrrolidone) (PVP). Effects of PVP molecular weight and concentration on the morphology and size distribution of the products were illustrated in this study. Molecular weight of PVP is significant for determining the morphology of Bi2Te3. The hexagonal nanoplates with high yield were obtained in the presence of PVP with molecular weight of 40000-45000. The average size and size distribution of Bi2Te3 nanoplates can be slightly varied by controlling concentration of PVP. High-yielded Bi2Te3 nanoplates exhibit characteristics of saturable absorption, identified by open-aperture Z-scan technique. The synthesized Bi2Te3 nanoplates with large saturation intensity of 4.6 GW/cm2 and high modulation depth of 45.95% generated a stable passively Q-switched fiber laser pulse at 1.5 μm. In comparison with recently reported Q-switched fiber lasers utilizing exfoliated Bi2Te3 nanosheets, our passive Q-switching operations could be conducted at a relatively low threshold power of 30.2 mW or a quite high output power of 99.45 mW by tuning the cavity parameters. [ABSTRACT FROM AUTHOR]

The ability to tune color output of nanomaterials is very important for their applications in laser, optoelectronic device, color display and multiplexed biolabeling. Here we first propose a femtosecond pulse shaping technique to realize the up-conversion fluorescence tuning in lanthanide-doped nanocrystals dispersed in the glass. The multiple subpulse formation by a square phase modulation can create different excitation pathways for various up-conversion fluorescence generations. By properly controlling these excitation pathways, the multicolor up-conversion fluorescence can be finely tuned. This color tuning by the femtosecond pulse shaping technique is realized in single material by single-color laser field, which is highly desirable for further applications of the lanthanide-doped nanocrystals. This femtosecond pulse shaping technique opens an opportunity to tune the color output in the lanthanide-doped nanocrystals, which may bring a new revolution in the control of luminescence properties of nanomaterials. [ABSTRACT FROM AUTHOR]