Search

Glass ceramics may exhibit enhanced functionalities compared to the glass and crystal counterparts due to the synergistic effect with the "1+1 > 2" feature in a cooperative manner. Nonlinear optical property is expected to be next breakthrough in presenting synergistic effect in glass ceramics. In this article, we give a comprehensive review of the recent progress of the development in nonlinear glass ceramics with unique photonic domain structure, emphasizing their synergistic effect in nonlinear response. The applications in photonics of the nonlinear glass ceramics are also described. Finally, we also present the opportunities and challenges for further exploring synergistic effect in nonlinear response in glass ceramics. [ABSTRACT FROM AUTHOR]

Rare-earth ion-doped upconversion (UC) micro/nanoparticles (UCM/NPs) could enable the conversion of near-infrared photons to high-energy emissions in the visible and ultraviolet regions. This unique property makes UCM/NPs highly attractive for applications in diverse fields, including materials science, photophysics, and biomedicine. However, ensemble spectroscopy ignores the heterogeneity in terms of size, shape, defects, surface groups, and charges of single UCM/NPs. Recently, the rapid development of single-particle spectroscopic techniques results in a gradual shift in the investigation of UC materials to heterogeneous nanoscale structures, unique photophysical phenomena, and advanced applications of single UCM/NPs, and the optical performance of a single UCM/NP has become a central topic in the community of UC materials. In this Perspective paper, we outline the characterization methods of a single UCM/NP and provide an overview of recent and on-going progress in investigations on single UCM/NPs, with a focus on their spectroscopic properties and applications in the polarization, waveguide, micro/nano-laser, super-resolution nanoscopy, and nanobarcode. Finally, current challenges and perspectives in this field are highlighted for future research. [ABSTRACT FROM AUTHOR]

Near‐infrared (NIR) photonic materials find extensive applications across important fields such as telecommunications, laser radar, and atmospheric remote sensing. In particular, photonic materials activated by main group elements, which exhibit unique spectral features including ultra‐broadband tunable luminescence and long lifetime, have become rising stars in NIR emitting dopants. In this review, the energy level characteristics of the p‐electrons to gain insight into the fundamentals of the NIR optical response from the main group elements are first introduced. Next, the NIR luminescence properties of the main group elements are discussed. Then, the strategy for the design of main group elements activated materials with the desired properties based on local chemical environment engineering is proposed. In addition, recent advances in the applications of main group element (excluding bismuth) activated materials are highlighted. Furthermore, the key scientific issues that urgently need to be solved for such materials, such as the detailed luminescence mechanism are highlighted. Anticipation also extends to the future research trends in this exciting field, including the ways for enhancing luminescence efficiency and extending spectral region, and the efforts for implementing these advancements in novel cutting‐edge technologies like photovoltaics and biomedicine. [ABSTRACT FROM AUTHOR]

Multimaterial fibers, as a new generation and rapidly developed fiber materials, have been widely used in advanced photonic and optoelectronic devices, energy conversion, optogenetics, smart fabrics, artificial muscles, micro/nano fabrications, 3D printing fields, etc. The great success of multimaterial fibers are mainly benefited from their multifunctionality, outstanding performance, and scalable manufacturing capability. In this review, a comprehensive review is given on the novel sensing principles, advanced manufacture techniques, and multifunctional sensing applications of multimaterial fibers. The development history of multimaterial fibers are introduced, and the importance of the appearance of multimaterial fibers are also evaluated. In addition, the commonly used fabrication techniques of multimaterial fibers with excellent scalability are summarized, and the general design strategies and working principles of multimaterial fibers are also highlighted. Furthermore, the recent advances of multimaterial fibers in diverse meaningful applications such as optical sensing, thermal sensing, chemical sensing, deformation sensing, microfluidic sensing, acoustic sensing, physiological sensing, neural sensing, radiation detection, and magnetic sensing are summarized. The future developments and challenges of multimaterial fibers are also indicated. In summary, this review is envisioned to not only provide fabrication methods and working principles of multimaterial fibers, but also demonstrate its great potentials in practical applications. [ABSTRACT FROM AUTHOR]

[Display omitted] • Tubular g-C 3 N 4 with different vacancies was prepared by temperature control. • Cu anchored in C vacancy showed lowest formation energy and shortest Cu-N bonds. • The presence of 1O 2 facilitated the effective degradation of carbamazepine. • The redox cycles of Cu(I)/Cu(II)/Cu(III) accelerated the Fenton-like reaction. • Five possible degradation pathways for carbamazepine were proposed. Efficient construction of the active site is crucial for Fenton-like reactions. In this study, tubular carbon nitride with different vacancies (V-TCN) was prepared by simple temperature control. The affinity of the nitrogen atom generated by the carbon vacancy was used to anchor single-atom Cu, which achieved the precise regulation of Cu, reduced agglomeration, and maximally exposed the active site to enhance the activation of H 2 O 2. Density functional theory calculations revealed that the single-atom Cu anchored in the C2 vacancy exhibited the lowest formation energy and the shortest Cu-N bonds. The results showed that Cu/V 550 -TCN had excellent degradation performance for the hard-to-degrade carbamazepine over a wide pH range (pH = 5–11), and singlet oxygen was the main active species during the degradation process. Additionally, the redox cycles of Cu(I)/Cu(II) and Cu(II)/Cu(III) accelerated the Fenton-like reaction. Five possible degradation pathways for carbamazepine were proposed based on liquid phase mass spectrometry analysis. This study provides a new insight into the role of surface defects in regulating the active site to promote the Fenton-like reaction for the degradation of stubborn pollutants. [ABSTRACT FROM AUTHOR]

We propose a k -domain spline interpolation method with constrained polynomial fit based on spectral phase in swept-source optical coherence tomography (SS-OCT). A Mach–Zehnder interferometer (MZI) unit is connected to the swept-source of the SS-OCT system to generate calibration signal in sync with the fetching of interference spectra. The spectral phase of the calibration signal is extracted by Hilbert transformation. The fitted phase–time relationship is obtained by polynomial fitting with the constraint of passing through the central spectral phase. The fitting curve is then adopted for k -domain uniform interpolation based on evenly spaced phase. In comparison with conventional k -domain spline interpolation, the proposed method leads to improved axial resolution and peak response of the axial point spread function (PSF) of the SS-OCT system. Enhanced performance resulting from the proposed method is further verified by OCT imaging of a home-constructed microspheres-agar sample and a fresh lemon. Besides SS-OCT, the proposed method is believed to be applicable to spectral domain OCT as well. [ABSTRACT FROM AUTHOR]

All-optical control of the noncentrosymmetry of azodye-doped polymer films was demonstrated by nonresonant dual-frequency coherent excitation. Three kinds of noncentrosymmetries of the polymer films were optically tailored using appropriate combinations of the writing beam polarizations, linearly polarized, and circularly polarized light. The tensor analysis of the photoinduced noncentrosymmetry was performed by monitoring second harmonic generation (SHG) of the samples. The quadratic dependence of SHG on film thickness was observed, indicating that a χ[sup (2)] grating satisfying the phase-matching condition for SHG was optically induced in the polymer films and that this nonresonant all-optical poling can be used to tailor the symmetry of bulk samples. © 2001 American Institute of Physics. [ABSTRACT FROM AUTHOR]

Phase-matched second-harmonic generation (SHG) in azodye-doped polymethylmethacrylate films was demonstrated using the nonresonant optical poling technique. During the seeding process, samples were irradiated simultaneously by coherent superposition of the fundamental and the second-harmonic light of a femtosecond laser. Optical poling experiments were performed at three wavelengths of 1500, 1320, and 1300 nm, respectively. The quadratic dependence of SHG on the film thickness showed that a χ[sup (2)] grating that satisfied the phase-matching condition for SHG was optically induced in the polymer films. The SHG conversion efficiency of a 105 μm thick film was estimated to be about 2%. A relaxation retardation effect of the photoinduced χ[sup (2)] was also observed in the thick films. © 2001 American Institute of Physics. [ABSTRACT FROM AUTHOR]

Deals with a study which examined wavelength dispersions in the Faraday effect of GaS[sub3/2]-GeS[sub2]-LaS[sub3/2]-based glasses containing various rare-earth ions. Experimental details; Results and discussion; Conclusion.

Although methods have been proposed to maintain high transverse resolution over an increased depth range, it is not straightforward to scale down the bulk-optic solutions to minimized probes of optical coherence tomography (OCT). In this paper, we propose a high-efficient fiber-based filter in an all-fiber OCT probe to realize an extended depth of focus (DOF) while maintaining a high transverse resolution. Mode interference in the probe is exploited to modulate the complex field with controllable radial distribution. The principle of DOF extension by the fiber-based filter is theoretically analyzed. Numerical simulations are conducted to evaluate the performances of the designed probes. A DOF extension ratio of 2.6 over conventional Gaussian beam is obtainable in one proposed probe under a focused beam diameter of 4 . 6 μ m . Coupling efficiencies of internal interfaces of the proposed probe are below −40 dB except the last probe–air interface, which can also be depressed to be −44 dB after minor modification in lengths for the filter. Length tolerance of the proposed probe is determined to be − 28 ∕ + 20 μ m , which is readily satisfied in fabrication. With the merits of extended-DOF, high-resolution, high-efficiency and easy-fabrication, the proposed probe is promising in endoscopic applications. [ABSTRACT FROM AUTHOR]

Glass is a noncrystalline amorphous solid showing glass transition characteristic. It can transform from one metastable state to another metastable or stable state in an external field. In glasses, novel functions can be achieved if we control the status, morphology, and distribution of external field-induced structures. In this article, we review controlled crystallization of glass by the external fields, that is, control of ligand field, local symmetry, and energy transfer of active ions, etc. by temperature field to achieve efficient broadband near-infrared emission and optical amplification. We also discussed highly localized crystallization in glass by electron beam and femtosecond laser. Finally, we introduced a novel process for the fabrication of glass ceramic fibers. [ABSTRACT FROM AUTHOR]

Transfer of energy occurs endlessly in our universe by means of radiation. Compared to energy transfer (ET) in free space, in solid state materials the transfer of energy occurs in a rather confined manner, which is usually mediated by real or virtual particles, including not only photons, but also electrons, phonons, and excitons. In the present review, we discuss the recent advances in optical ET by resonance mediated with photons in solid materials as well as their nanoscale counterparts, with focus on the photoluminescence behavior pertaining to ET between optically active centers, such as rare earth (RE) ions. This review begins with a brief discussion on the classification of optical ET together with an overview of the theoretical formulations and experimental method for the examination of ET. We will then present a comprehensive discussion on the ET in practical systems in which normal photoluminescence, upconversion and quantum cutting resulted from ET involving metal ions, QDs, organic species, 2D materials and plasmonic nanostructures. Diverse ET systems are therefore simply categorized into cases of ion–ion interactions and non-ion interactions. Special attention has been paid to the progress in the manipulation of spatially confined ET in nanostructured systems including core–shell structures, as well as the ET in multiple exciton generation found in QDs and organic molecules, which behave quite similarly to resonance ET between metal ion centers. Afterwards, we will discuss the broad spectrum of applications of ET in the aforementioned systems, including solid state lighting, solar energy utilization, bio-imaging and diagnosis, and sensing. In the closing part, along with a short summary, we discuss further research focus regarding the problems and possible future directions of optical ET in solids. [ABSTRACT FROM AUTHOR]

Bi-doped glasses have been paid much attention since the first observation of the broadband near-infrared emission. Great progress has been achieved in this area of research and development in the last decade. In this review article, we aim to present some recent research development on Bi-doped glasses carried out mainly by our group. Firstly, the mechanism of NIR emission is summarized and analyzed based on experimental data and first principle calculation. Then, we introduce new strategies for enhancing the NIR emission through mixed network effect, topological network structure control, and codoping. Finally, we elaborate the representative results about optical nonlinear effect, optical amplification, and lasing property of Bi-doped glasses. Some important related results obtained by other groups are also mentioned. [ABSTRACT FROM AUTHOR]

Abstract: A switchable quadruple-wavelength erbium-doped photonic crystal fiber laser is proposed and demonstrated experimentally by employing a simple linear cavity configuration incorporating a polarization-maintaining photonic crystal fiber Sagnac loop filter. The laser can be switched flexibly from single-wavelength to quadruple-wavelength by adjusting a polarization controller and all of lasing lines locate at fixed wavelength positions in the range of 1556nm to 1560nm. The laser individually has a kind of single wavelength and quadruple-wavelength output mode. It also has three and two kinds of dual-wavelength and triple-wavelength output modes, respectively. The laser with good intensity uniformity exhibits excellent wavelength and power stabilities in the experiment. [Copyright &y& Elsevier]

Abstract: Transparent strontium titanium silicate glass–ceramics (GCs) containing Ni2+-doped SrTiO3 nanocrystals were synthesized by heat treatment method. Absorption spectra confirmed that the coordination environment of Ni2+ ions was changed from the trigonal bipyramid fivefold sites in as-cast glasses to the octahedral sites in the GCs. Upon 980nm laser excitation, the GCs exhibited broadband near-infrared emissions covering 1.1–1.7μm wavelength region with the full width at half maximum (FWHM) of more than 290nm and fluorescent lifetime of up to 735μs, which originated from the 3T2g (3F)→ 3A2g (3F) transition of octahedral Ni2+ ions in the SrTiO3 nanocrystals. This kind of Ni2+-doped transparent GCs have potential applications in super-broadband optical amplifiers and tunable lasers. [Copyright &y& Elsevier]

Abstract: Mercury emission from coal combustion is an increasing environmental concern due to its high volatility and toxicity, and activated carbon (AC) adsorption has been proven an effective mercury-control method, with high-cost limit. The renewable bioresource of bamboo constitutes an important precursor for activated carbon, and the bamboo charcoal (BC) may act as low-cost sorbent used in the mercury-control. The adsorptive potential of BC and modified BC using H2O2 for elemental mercury was investigated for the first time through a parametric study conducted with a bench-scale bed. The effects of pore structure and surface chemistry were investigated based on BET, XPS. Which suggest that BC materials have excellent adsorption potential for elemental mercury, especially after modified by H2O2. The modification using H2O2 altered the physical and chemical properties of BC materials, making the sorbents more effective in mercury adsorption even at a relative higher temperature, and the enhancing-effect was more obvious with increasing H2O2. [Copyright &y& Elsevier]

Abstract: A 120fs Ti–sapphire laser was used to fabricate waveguides in YAG crystal. A 7mm long waveguide was written at a position of 100μm below the surface, which shows multimode propagation at 633nm with optical attenuation of about 0.2dB/mm. The light guiding occurs in the region around the visible laser-damaged region, indicating that the light guiding area is induced by stress. The waveguide exhibited strong birefringence property with maximum magnitude of about 1.5×10−5. Infrared and Raman spectroscopy analysis indicate there is no change in chemical composition in laser-modified zone. [Copyright &y& Elsevier]

Abstract: An efficient near-infrared (NIR) quantum cutting (QC) involving the emission of two near-infrared photons for each blue photon absorbed is realized in RE3+/Yb3+ (RE=Pr, Tb, and Tm): GeO2–B2O3–ZnO–LaF3 glasses. Upon excitation of Pr3+, Tb3+, and Tm3+ ions with visible photons at 482, 483, and 467nm two near-infrared photons at 950–1100nm (Yb3+:2F5/2 → 2F7/2) through an efficient cooperative energy transfer from Pr3+, Tb3+, and Tm3+ to Yb3+, with an optimal quantum efficiency close to 200% has been demonstrated. The development of the near-infrared quantum cutting oxyfluoride glasses could open a route in achieving high efficiency silicon-based solar cells by means of downconversion in the visible part of the solar spectrum to ∼1000nm photons with a two fold increase in the photon number. [Copyright &y& Elsevier]

Abstract: In this paper, we report the influence of silver nanoparticles (NPs) on the luminescence properties of TeO2–ZnO–Nb2O5–MoO3 glass doped with trivalent praseodymium (Pr3+) ions. From the XRD, Raman and DTA measurements, glasses structural and thermal properties were determined. The experiments were performed with samples containing different concentrations of NPs controlled by heat-treatment of the glass. The enhancement of the Stokes luminescence with an increase of the NPs concentration was observed for these samples excited at 470nm. The influence of the NPs on the frequency upconversion (anti-Stokes) emissions of Pr3+ under excitation at 586nm was also investigated, in resonance with the 3H4→1D2 transition. The excited Pr3+ ions exchange energy in the presence of the nanoparticles, originating efficient conversion from orange to blue. The enhancement in the intensity of the luminescence at ∼493nm, corresponding to the 3P0→3H4 transition, is due to the influence of the large local field on the Pr3+ ions, which are located near the metallic nanoparticles. [Copyright &y& Elsevier]

Abstract: In this paper, we present the photoluminescence properties of Eu3+, Tb3+ and Tm3+-doped oxyfluoride alumino-silicate glasses and glass ceramics. The X-ray diffraction (XRD) and differential thermal analysis (DTA) profiles of these glasses have been carried out, to confirm their structure and thermal stability. Compared to Eu3+, Tb3+ and Tm3+-doped glasses, their respective glass ceramics have shown stronger emissions due to the presence of LiGdF4 crystalline phase. For Eu3+-doped glass and glass ceramics, five emission bands centered at 578nm (5D0 → 7F0), 592nm (5D0 → 7F1), 614nm (5D0 → 7F2), 652nm (5D0 → 7F3) and 698nm (5D0 → 7F4) have been observed with 394nm (5D0 → 7L6) excitation wavelength. Of them, 614nm (5D0 → 7F2) has shown bright reddish-orange emission. With regard to the Tb3+-doped glass and glass ceramic, four emission bands centered at 491nm (5D4 → 7F6), 545nm (5D4 → 7F5), 587nm (5D4 → 7F4) and 622nm (5D4 → 7F3) have been observed with an excitation at 377nm (3F6 → 5G6) wavelength. Of them, 545nm (5D4 → 7F5) has shown bright green emission. Emission bands of 1G4 → 3F4 (650nm) and 3F3 → 3H6 (708nm) transitions for the Tm3+:glass and glass ceramic, with an excitation at 3H6 → 1G4 (469nm) have been observed. The stimulated emission cross-sections of all the emission bands of Eu3+, Tb3+ and Tm3+:glasses and glass ceramics have been computed based on their measured full-width at half maximum (FWHM, Δλ) and lifetimes (τ m). [Copyright &y& Elsevier]

Abstract: In this paper, we present the photoluminescence properties of Pr3+, Sm3+ and Dy3+-doped transparent oxyfluoride alumino-silicate glasses. These glasses have shown strong emission and absorption bands in visible and near-infrared (NIR) region. From the measured absorption spectra, Judd–Ofelt (J–O) intensity parameters (Ω 2, Ω 4 and Ω 6) have been calculated for all the studied ions. For Pr3+-doped glass, emission bands centered at 532nm (3P0 → 3H5), 615nm (3P0 → 3H6) and 647nm (3P0 → 3F2) have been observed with 486nm (3H4 → 3P0) excitation wavelength. Of them, 647nm (3P0 → 3F2) has shown bright red emission. Emission bands of 4G5/2 → 6H5/2 (563nm), 4G5/2 → 6H7/2 (599nm) 4G5/2 → 6H9/2 (645nm) and 707nm (4G5/2 → 6H11/2) for the Sm3+:glass, with excitation at 6H5/2 → 4F7/2 (403nm) have been recorded. Of them, 4G5/2 → 6H7/2 (599nm) has shown a bright orange emission. With regard to the Dy3+:glass, a bright fluorescent yellow emission at 575nm (4F9/2 → 6H13/2) and blue emission at 484nm (4F9/2 → 6H15/2) have been observed, apart from 4F9/2 → 6H11/2 (663nm) emission transition with an excitation at 388nm (6H15/2 → 4I13/2 + 4F7/2) wavelength. The stimulated emission cross-sections of all the emission bands of Pr3+, Sm3+ and Dy3+:glasses have been computed based on their measured full-width at half maximum (FWHM, Δλ) and measured lifetimes (τ m). [Copyright &y& Elsevier]

Abstract: In this paper, we present the absorption and photoluminescence properties of Pr3+, Sm3+ and Dy3+-doped transparent oxyfluoride alumino-silicate glass ceramics and Sm3+ and Dy3+-doped oxyfluoride germanate glasses. The X-ray diffraction (XRD) and differential thermal analysis (DTA) profiles of these glasses have been carried out, to confirm their structure and thermal stability. These glasses or glass ceramics have shown strong emission and absorption bands in visible and near-infrared (NIR) region. From the measured absorption spectra, Judd–Ofelt (J–O) intensity parameters (Ω 2, Ω 4 and Ω 6) have been calculated for all the studied ions. Compared to Pr3+, Sm3+ and Dy3+ doped glasses, their respective glass ceramics have shown stronger emissions due to LiGdF4 crystalline phase in alumino-silicate glass ceramics. For Pr3+ doped glass and glass ceramic, emission bands centered at 527nm(3P0→3H5), 610nm(3P0→3H6), 640nm(3P0→3F2), 678nm(3P1→3F3), 702nm(3P0→3F3) and 721nm(3P0→3F4) have been observed with 445nm(3H4→3P2) excitation wavelength. Of them, 640nm(3P0→3F2) has shown bright red emission. Emission bands of 4G5/2→6H5/2 (562nm), 4G5/2→6H7/2 (598nm), 4G5/2→6H9/2 (644nm) and 706nm(4G5/2→6H11/2) for the Sm3+: glass and glass ceramic, with excitation at 6H5/2→4F7/2 (402nm) have been recorded. Of them, 4G5/2→6H7/2 (598nm) has shown a bright orange emission. With regard to the Dy3+: glass and glass ceramic, a bright fluorescent yellow emission at 576nm(4F9/2→6H13/2) and blue emission at 485nm(4F9/2→6H15/2) have been observed, apart from 4F9/2→6H11/2 (662nm) emission transition for glass ceramic with an excitation at 388nm(6H15/2→4I13/2+4F7/2) wavelength. For germanate glasses, emission bands of 4G5/2→6H5/2 (564nm), 4G5/2→6H7/2 (601nm), 4G5/2→6H9/2 (644nm) and 705nm(4G5/2→6H11/2) for the Sm3+: glass, with an excitation at 6H5/2→4F7/2 (401nm) have been recorded. Of them, 4G5/2→6H7/2 (601nm) has shown a bright orange emission. With regard to the Dy3+: glass, a bright fluorescent yellow emission at 576nm(4F9/2→6H13/2) and blue emission at 482nm(4F9/2→6H15/2) have been observed, apart from 4F9/2→6H11/2 (661nm) emission transition with an excitation at 386nm(6H15/2→4I13/2+4F7/2) wavelength. The stimulated emission cross-sections of all the emission bands of Pr3+, Sm3+ and Dy3+: glasses and glass ceramics have been computed based on their measured full-width at half maxima (FWHM, Δλ) and measured lifetimes (τm ). [Copyright &y& Elsevier]

Abstract: Experimental evidence for long-range compositional fluctuations in glasses is given. The implications for electronic structure and stoichiometry-induced structural variations are analyzed. These fluctuations were discovered by examining the spatial dependence of inner shell near-edge absorption spectra obtained using a 50nm diameter probe. This spectroscopy is sensitive to both angular and distance correlations in bonding. Comparisons with spectra from compositionally equivalent crystals, and multiple-scattering calculations which include core-hole effects are used to analyze the data. [Copyright &y& Elsevier]

Abstract: Precipitation behaviors of metallic nanoparticles inside silicate glasses by femtosecond laser irradiation are studied in this work. Laser irradiation results easily in precipitation of metallic nanoparticles where colors depend in part on their sizes and quantities. Laser irradiation induced precipitation of metallic nanoparticles displays the different behaviors from that in the unirradiated area inside glasses and their mechanisms are investigated. [Copyright &y& Elsevier]

Abstract: Broadband infrared luminescence is observed in various Bi-doped oxide glasses prepared by conventional melting-quenching technique. The absorption spectrum of the Bi-doped germanium oxide glass consists of five broad peaks at below 370, 500, 700, 800 and 1000nm. The fluorescence spectrum exhibits a broad peak at about 1300nm with full width at half maximum (FWHM) of more than 300nm when excited by an 808nm laser diode. The fluorescence lifetime at room temperature decreases with increasing Bi2O3 concentration. Influence of the glass composition and melting atmosphere on the fluorescence lifetime and luminescent intensity is investigated. The mechanism of the broadband infrared luminescence is suggested. The product of stimulated emission cross-section and lifetime of the Bi-doped aluminophosphate glass is about 5.0×10−24 cm2 s. The glasses might be promising for applications in broadband optical fiber amplifiers and tunable lasers. [Copyright &y& Elsevier]

Abstract: In the past decades, femtosecond laser has been widely used to study the interaction between light and matter, and dynamic processes of various reactions. In this article, we review femtosecond laser-induced microfeatures in glasses and their promising applications in micro-optics and optoelectronics. Various highly localized microstructures, e.g. color center defects, refractive index change, micro-void and micro-crack, have been observed in the glasses after the femtosecond laser irradiation. The mechanisms of the observed phenomena are discussed. We also demonstrate the fabrication of various micro-optical components, e.g. three-dimensional optical memory, optical waveguide, micro-grating, micro-lens and fiber attenuator, by using the femtosecond laser-induced structures. [Copyright &y& Elsevier]

Abstract: Near-infrared to ultraviolet upconversion luminescence was observed in the Pr3+:Y2SiO5 crystal with 120fs, 800nm infrared laser irradiation. The observed emissions at around 270nm and 305nm could be assigned to 5d→4f transitions of Pr3+ ions. The relationship between the upconversion luminescence intensity and the pump power of the femtosecond laser reveals that the UV emission belongs to simultaneous three-photon absorption induced upconversion luminescence. [Copyright &y& Elsevier]

Abstract: Near-infrared to UV and visible upconversion luminescence was observed in single-crystalline ZnO under an 800nm infrared femtosecond laser irradiation. The optical properties of the crystal reveal that the UV and VIS emission band are due to the exciton transition (D 0 X) bound to neutral donors and the deep luminescent centers in ZnO, respectively. The relationship between the upconversion luminescence intensity and the pump power of the femtosecond laser reveals that the UV emission belongs to three-photon sequential band-to-band excitation and the VIS emission belongs to two-photon simultaneous defect-absorption induced luminescence. A saturation phenomenon and polarization-dependent effect are also observed in the upconversion process of ZnO. A very good optical power limiting performance at 800nm has been demonstrated. The two- and three-photon absorption coefficients of ZnO crystal were measured to be 0.2018cmGW−1 and 7.102×10−3 cm3 GW−2, respectively. The two- and three-photon cross sections were calculated to be 1.189×10−51 cm4 s and 1.040×10−80 cm6 s2, respectively. [Copyright &y& Elsevier]

Abstract: Damage threshold of crystals SiO2 and YAG against 60–900fs, 800nm laser pulses are reported. The breakdown mechanisms were discussed based on the double-flux model and Keldysh theory. We found that impact ionization plays the important role in the femtosecond laser-induced damage in crystalline SiO2, while the roles of photoionization and impact ionization in YAG crystals depend on the laser pulse durations. [Copyright &y& Elsevier]

Abstract: We report transparent Ni2+-doped ZnO–Al2O3–SiO2 system glass-ceramics with broadband infrared luminescence. After heat-treatment, ZnAl2O4 crystallite was precipitated in the glasses, and its average size increased with increasing heat-treatment temperature. No infrared emission was detected in the as-prepared glass samples, while broadband infrared luminescence centered at 1310nm with full width at half maximum (FWHM) of about 300nm was observed from the glass-ceramics. The peak position of the infrared luminescence showed a blue-shift with increasing heat-treatment temperature, but a red-shift with an increase in NiO concentration. The mechanisms of the observed phenomena were discussed. These glass-ceramics are promising as materials for super broadband optical amplifier and tunable laser. [Copyright &y& Elsevier]

Abstract: We report ultrabroad infrared luminescence from Bi-doped aluminogermanate glasses. The infrared luminescence almost covers the whole low loss wavelength region (1200–1650 nm) of silica glass fiber when excited by a diode laser at 980 nm. The full width at half maximum (FWHM) of the luminescence is 510 nm. The luminescence peak can be divided into three Gaussian peaks, and the fluorescence lifetime of the three emissions are 297 μs, 470 μs and 1725 μs, respectively. These fluorescence properties indicate that the glasses are promising material for broadband optical amplifiers. [Copyright &y& Elsevier]

Abstract: In 1.30BaO·6Al2O3:Eu and 0.82BaO·6Al2O3:Eu with β′- or β-alumina structure respectively, prepared in air, the doped Eu3+ ions were partially reduced to Eu2+ ions. X-ray powder diffraction patterns and photoluminescent spectra were employed to characterize the compound structures and to detect the existence of Eu2+ ions, respectively. The reduction mechanism of Eu3+→Eu2+ was proposed to be due to the existence of negative defects (e.g. ) in these compounds. This is the first observation of the reduction of Eu3+→Eu2+ in non-stoichiometric compounds prepared in an oxidizing atmosphere. And the luminescent properties of Eu2+ in the compounds of xBaO·6Al2O3:Eu2+ (x=0.82, 1.00, 1.30) showed similar behavior due to their similarity in crystal structures. [Copyright &y& Elsevier]

The behaviours of three mineral elements (Na, Fe and Si) during coal combustion in the temperature range 400–2200 K, pressure 1×105 Pa, under both oxidizing and reducing conditions, have been studied in detail by a thermodynamic equilibrium analysis.The effects of atmosphere and temperature on the speciation of mineral species are discussed. It was found that the combustion conditions greatly affect the major speciation of mineral, since it influences, to some extent, the vaporization of theses elements; When the temperature is above 1700 K, Na(g), NaOH(g), Fe(g) and SiO(g) are dominant gaseous species. The dominant species of mineral in flue gases depend on both the combustion conditions (reducing or oxidizing) and the type of coal. [Copyright &y& Elsevier]

Gold nanoparticles were precipitated inside gold ion-doped glasses after irradiation by a femtosecond laser, a nanosecond laser or X-ray and successive annealing. Experimental results show that the irradiation resulted in decrease of minimum annealing temperature and critical size for the precipitation of gold nanoparticles. The observed phenomenon has promising applications for the fabrication of multi-colored images inside transparent materials, optical memory and integrated micro-optical switches. [Copyright &y& Elsevier]

This Letter, reports the focused-femtosecond-laser induced dissolution of gold nanoparticles in an Au+-doped glass. Gold nanoparticles, pre-precipitated in the glass either by thermal treatment or by irradiation of a focused femtosecond laser and successive thermal treatment, are broken to dissolve when they are reirradiated by a focused femtosecond laser. It is suggested that the dissolution of gold nanoparticles is due to dramatically increasing in the temperature of gold nanoparticles, resulting from the energy absorbing from the femtosecond laser. A repeatable process of precipitation and dissolution of gold nanoparticles is also realized anywhere selected inside the glass, so does the control of the size of gold nanoparticles. [Copyright &y& Elsevier]

We report on precipitation of Ag nanoparticles in silicate glasses by a femtosecond laser irradiation and successive annealing. Effect of Al2O3 on the precipitation of Ag nanoparticles in glasses was investigated. Absorption spectra show that introducing a small amount of Al2O3 results in inhibition of color centers generation and an apparent increase of the annealing temperature for the precipitation of Ag nanoparticles. The mechanisms of the observed phenomena are discussed. [Copyright &y& Elsevier]

In order to utilize the solid residues simultaneously with clean and high-combustion efficiency when firing high sulfur and ash coal sludge generated in coal washing process in China, the mineral composition and usability of combustion solid products were investigated when injecting compound additives into series of coals or coals blended with sludges. In this study, a single burner furnace was used for combustion test and the solid residues were analyzed by means of X-ray powder diffraction method. The influences of temperature, residence time, and compound additives on mineral characteristics of the residues have been discussed. The results indicate that, the compositions of solid products are principally free oxides and a small amount of gehlenite, dicalcium silicate, etc. below 1000 °C; when the firing temperature increases above 1100 °C, the major minerals are gehlenite and dicalcium silicate. Also it can be found that several seconds is not enough for mineral complete reaction, and suitable calcium oxide content and particles fineness are recommended. The result of combustion test shows that there is no evident effect on ignition and combustion when the additive/coal (a/c) ratio is below 30% by weight; and the normal stable combustion with ignition delay can be achieved when the a/c ratio is ranging between 30 and 50%; but the a/c ratio exceeding 50% will damage combustion and even result in fire extinction. Industrial test results indicated that the solid residues was composed of silicate mineral rich in belite by adopting compound additives, but the comprehensive reaction mechanism needs further studies as well as the effect of additives on combustion should be concerned. [Copyright &y& Elsevier]

Optical fibers have been formed by replacing precursor glass core with precursor ceramic core, in which drawing process, the precursor ceramic melted to fill the space of the core region while the clad glass was softened. Nd3+ doped LaNbO 4 nanocrystals were precipitated in the core after heat treatment. X-ray diffraction, Raman spectra, high-resolution transmission electron microscopy, electron paramagnetic resonance, optical microscope, and photoluminescence were used to characterize the obtained fiber. No crystallization, cracking, bubble, or undissolved substance is observed in the core region of precursor fiber. Nd3+ doped LaNbO 4 nanocrystals are precipitated in the core region after thermal treatment. Under the pumping source of 808 nm, three emission bands located at ∼887 nm, ∼1064 nm, and ∼1337 nm are observed, which makes this GC fiber a promising material for the NIR fiber amplifier. [ABSTRACT FROM AUTHOR]

Ultrafast fiber lasers, due to their short pulse duration, excellent beam quality, and high brightness, are extensively used in precision processing, biomedicine, nonlinear optics, and spectroscopy. However, great challenges still exist in improving the optical conversion efficiency in glass‐based gain media because of the high non‐radiative transition probability. Here, we demonstrate an oxyfluoride glass–ceramic (GC) fiber containing NaYF4:Yb3+ nanocrystal that enables enhanced 1064‐nm continuous‐wave laser output with an optical signal‐to‐noise ratio of 60 dB. Compared with the as‐prepared glass fiber, the optical conversion efficiency of GC fiber is improved from 24.2% to 30.0%. The improvement of laser action is mainly caused by the preferential incorporation of Yb3+ into the NaYF4 nanocrystal with low phonon energy. Using this well‐developed GC fiber, we successfully built a passively mode‐locked pulsed fiber laser that deliveries laser pulses with a pulse duration of 8.1 ps and a repetition frequency of 56.92 MHz. These results highlight that the GC strategy may provide a roadmap for the development of ultrafast fiber laser and the application of GC fibers in various optoelectronic fields. [ABSTRACT FROM AUTHOR]

Phosphor‐in‐silica glass (PiSG) composite is an excellent candidate for highly stable and efficient color converter in high power white light emitting diodes (wLEDs). However, the high‐throughput fabrication of PiSG with different shapes is still challenging for current techniques. Here this study reports the manufacture of transparent PiSG based on YAG:Ce (Y3Al5O12:Ce3+) using injection molding (IM) technique. In this approach, different shapes of centimeter‐sized YAG:Ce‐PiSG pieces are fabricated by using IM of a YAG:Ce/amorphous silica nanoparticles/thermoplastic polymer composite at low temperatures (@ 150 °C) which afterward are debound (@ 600 °C) and densified (@ 1150 °C). Interestingly, the molding time to produce YAG:Ce/silica/polymer green parts is 5 s per piece, implying the capability for high‐throughput production of YAG:Ce‐PiSG. Furthermore, the as‐fabricated YAG:Ce‐PiSG exhibits high luminescence efficiency (>91%) and high chemical/thermal stabilities. Accordingly, high power wLEDs (10 W) are fabricated using the YAG:Ce‐PiSG which demonstrates high luminous efficiency of 144 lm W−1 at 50 mA, closing to that of the wLEDs fabricated by expensive YAG:Ce ceramic plate (i.e., 149 lm W−1 @ 50 mA). The work provides a facile and universal approach for industry‐scale production of PiSG that can be promising for various photonic applications. [ABSTRACT FROM AUTHOR]

Broadband near‐infrared (NIR) emitting materials have gained considerable attention for their applications in lighting, displays, sensing, bio‐imaging, and optical amplification. Recently, numerous excellent broadband NIR emitting materials are developed by introducing Cr3+, Bi+, or Ni2+ ions to various hosts. However, there is a notable absence of reports on ultra‐broadband NIR emitters spanning the entire telecommunication window as well as the NIR‐I (700–1000 nm) and NIR‐II (1000–1700 nm) biological windows activated by vanadium ions. Herein, the study presents, for the first time to the best of the knowledge, ultra‐broadband NIR emission ranging from 850 to 1600 nm (peaking at ≈1000 nm) at room temperature in vanadium‐doped phosphate glass. Detailed spectra and microscopic structure analysis reveal that two V3+‐emitting centers predominantly contribute to the ultra‐broadband emission, corresponding to 3T2(3F)→3A2(3F) spin‐allowed and 3T2(3F)→1E(1D) spin‐forbidden electron transitions of tetrahedrally coordinated V3+ ions. Notably, the tunability of NIR emission peak is demonstrated by adjusting the local glass structure or the vanadium doping content. Moreover, glass‐converted light‐emitting diodes (gc‐LEDs) are fabricated from vanadium‐doped glass, and the potential applications are demonstrated. The work opens new avenues for the design and fabrication of broadband NIR‐emitting materials and opto‐electronic devices. [ABSTRACT FROM AUTHOR]

The construction of active materials with controllable optical response facilitates the development of advanced photonic devices. However, the achievement of robust active materials with wide wavelength tunable and broadband emission remains a great challenge, mainly due to the fixed energy levels of conventional active dopants and limited inhomogeneous broadening in common hosts. Here, the study proposes that the cluster in the mesoscopic scale of ≈1 nm may break this bottleneck issue and demonstrate a strategy for the management of photon emission by engineering the cluster evolution. The amorphous glass as the host to tailor the characteristic configuration of Te clusters from 1 to 2 nm by control of the topological structures in glass is employed. Impressively, it presents a distinct optical response totally different from the conventional active centers and this enables to construct of active photonic glass with continuously tunable emission from 888 to 1064 nm. More importantly, Te cluster‐activated photonic glass fibers are fabricated and the broadband on‐off gain is successfully achieved. Furthermore, benefiting from the unique tunable emission, novel near‐infrared devices are constructed and their application in imaging is demonstrated. The approach of cluster engineering mediated tunable optical response is believed to bring new opportunities for developing advanced photonic devices. [ABSTRACT FROM AUTHOR]

Transparent glasses are ideal and robust hosts for a range of emission centers, while the simultaneous manipulation of the temporal and spectral characteristics of emission remains a tremendous challenge for inorganic glasses. Here, the development and functionalization of melt‐quenched transparent coordinate polymer glasses with a tailorable ultralong room‐temperature phosphorescence are demonstrated. Dynamic modulation of the phosphorescence is achieved by utilization of the high molecular rigidity and manipulation of the spin‐orbital coupling effects within the glass systems. By introducing dye molecules into the glasses, Phosphorescence resonance energy transfer from the glass matrix to the dye molecules is exploited and controllable multicolor long‐lived luminescence is demonstrated. Further design of the component and concentration of the encapsulated dyes allows for wavelength‐tunable long‐lived delayed fluorescence via an efficient delayed sensitization process, featuring a tunable emission spectrum covering a wide range from 520 to 630 nm. Leveraging the multiple spectral tuning channels of the hybrid glass, multi‐mode optical information storage, and dynamic anti‐counterfeiting applications are further demonstrated. This work provides a new hybrid material platform and design methodology for realizing lifetime‐adjustable and wavelength‐tunable long‐lived luminescence, which can find wide applications in time‐rsesolved information display, high‐density information storage, and dynamic anti‐counterfeiting. [ABSTRACT FROM AUTHOR]

Highly efficient and programmable writing of multidimensional optical data is of great value for next‐generation high‐throughput information technologies but has been rarely achieved. Here, a one‐step frame printing of chromatic pixels in lithium niobate crystal by using a single ultrafast laser pulse is reported. In this strategy, a phase superposition‐based spatial light modulation strategy is applied to split a single ultrafast laser pulse into multiple son pulses with designated optical properties and spatial distribution patterns. It is demonstrated that these son pulses allow for massively creating micro‐amorphous phase transition zones with on‐demand structural features that can modulate the intrinsic birefringence of the crystal matrix and generate wavelength‐selective interference in the visible band to form pixel‐level chromatic patterns, namely, single‐pulse‐driven frame color printing. The created chromatic pixels can be encoded into computer‐recognizable data arrays to play a role in high‐efficiency multidimensional information recording. The presented approach enables fast and programmable information batch writing in 3D space and can serve as a versatile tool boosting next‐generation information optics. [ABSTRACT FROM AUTHOR]

The rational control of intrinsic defects in materials can significantly enhance their scientific and technological potentials, but it remains a long‐standing challenge in nanocrystal‐in‐glass composites (NGCs). Herein, a defect engineering strategy mediated by the mixed alkali effect is proposed and experimentally demonstrated for NGCs. Interestingly, the hybridization of large alkali ions can effectively increase the barrier of Li+ migration and reduce the Li‐related defects in LiNbO3 NGC. As a result, a novel LiNbO3 NGC with greatly reduced Li‐related defects, high crystallinity of over 60%, and excellent optical transmission are successfully fabricated. This unique NGC configuration facilitates efficient transverse second harmonic generation (TSHG) in a broad wavelength region. Based on the above effects, a standard TSHG device is fabricated and implemented to monitor ultrashort optical pulses with duration in the order of ≈10−13 s over a broad wavelength region, down to 780 nm. The proposed strategy not only provides a new idea for defect engineering in materials science but also has great significance for boosting the practical applications of NGCs in ultrashort optical pulse monitoring. [ABSTRACT FROM AUTHOR]

Efficient light sources with emission spanning from visible to infrared range are of central importance for applications including precision spectroscopy and sensing. Under irradiation with constant‐wave (CW) lasers, here, the generation and modulation of incandescence‐like ultra‐broad emission (600–4000 nm) from random aggregates of metal oxide nanoparticles are demonstrated by judicious doping of free carriers, that of any existing photoluminescence process and commercial broadband light sources. It is revealed that this emission is associated with a dominant thermal origin and it is characterized by a pump‐dependent nonlinear response with the maximum order of nonlinearity exceeding 8, which is benefited from the intensified light‐matter interaction mediated by the high density of hot spots in the random plasmonic nanostructures. Moreover, by leveraging the prominent plasmon response, the emission spectra and intensity can be tuned by the Drude terms of the oxide nanoparticles. the use of this broadband infrared (IR) emission is exploited further as the light source for the demonstration of IR spectrometry, exemplified by the examination of organic molecules. The method for producing strong and continuum IR emission based on engineered plasmonic oxide can stimulate further exploitation of miniaturized IR light sources for applications including imaging and sensing. [ABSTRACT FROM AUTHOR]

Flexible regulation of bandgap of perovskite nanocrystals (PNCs) is fundamentally critical for desirable optoelectronic functions and applications. Here, regulating chemical composition and emission wavelength of PNCs in glass by a simple heat‐treatment process are reported, which is established to rely on the thermal‐trigger phase separation and ion exchange. The first principle calculations are overall performed to reveal the mechanism of bandgap engineering and optimization of emission performance. The PNCs exhibit excellent stability against thermal, ultraviolet irradiation, and organic molecules. The bandgap of PNCs in the heat‐treated glass can also be re‐modulated by ultrafast laser irradiation. Ultrafast laser direct writing of multi‐color patterns and holographic dynamic displays are achieved, which hold great potential in the application of encryption‐decryption and emissive devices. [ABSTRACT FROM AUTHOR]

All inorganic halide perovskite quantum dots (PQDs) exhibit excellent optical properties and have been intensively exploited for diverse applications in the field of optoelectronics. However, their inherent frangibility remains an enormous challenge for both practical applications and scientific research. The recently emerged oxide glasses doped with such PQDs exhibit high stability against degradation, which is promising for practical applications. Here, borosilicate glasses doped with CsPbBr 3−x I x PQDs were prepared by the traditional melt-quenching and subsequent annealing process. By introducing alkaline metal oxides as the glass network modifier to adjust glass network structure, the optical properties of the precipitated PQDs are significantly enhanced. The photoluminescence (PL) intensity and photoluminescence quantum yield (PLQY) can be enhanced by up to 200 % and 29 % for the sample fabricated under optimal conditions, respectively. By leveraging the strong PL of the developed PQD-doped glasses, we demonstrate the fabrication of phosphor-converted light emitting devices for white light illumination and plant illumination based on samples with PL peak wavelengths at approximately 570 nm and 650 nm, respectively. [ABSTRACT FROM AUTHOR]

By combining the spectroscopic quality of a crystalline phase with the outstanding thermal and chemical stability of the matrix glass, nanocrystal‐in‐glass composites (NGCs) exhibit excellent optical properties. However, strong interfacial diffusion occurs during high‐temperature encapsulation, leading to the erosion of the nanocrystals and detrimental effects on the final performance. The control of interfacial diffusion has so far relied on intuition and experience, with the underlying physical mechanisms remaining largely unknown. In this study, through atomistic simulations and experimental verification, we have developed atomic models of NGCs, revealing the dynamic characteristics of the interface and elucidating how the glass structure can regulate the interface diffusion. Finally, we demonstrate how a tunable interface can be achieved through compositional adjustments of the glass matrix. [ABSTRACT FROM AUTHOR]

Quantum cutting (QC) is a promising approach for enhancing the energy conversion efficiency of solar cells since it allows for conversion of one ultraviolet photon from the sun into two near-infrared photons with energy comparable to the band gap of silicon solar cells. We find that QC can occur by cooperative energy transfer from Eu2+ to Yb3+ in soda-lime-silicate glasses subjected to thermal reduction around the glass transition temperature. Besides the QC effect, the thermal reduction results in improvement of surface performances, e.g., hardness. This synergy effect potentially makes the thermally reduced glass an ideal solar cell substrate material. [ABSTRACT FROM AUTHOR]