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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]

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]

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]

CsPbI3 perovskite quantum dots (QDs) doped borosilicate glass was prepared by the process of melt‐quenching and subsequent annealing. With the introduction of ZnO to the parent glass as the glass network intermediate, the optical properties of the resultant samples are dramatically enhanced. Both the photoluminescence (PL) intensity and photoluminescence quantum yield (PLQY) shows a strong dependence on ZnO concentration as ZnO is found to facilitate the precipitated of the QDs by reducing the connectivity of three‐dimensional glass network built from SiO4 tetrahedrons. The tunable visible‐band PL emission of the CsPbI3 QD‐doped glass could find potential applications in white LEDs and lasers. [ABSTRACT FROM AUTHOR]

For the fiber‐based magneto‐optical (MO) devices, like Faraday optical isolator, the target MO glasses are supposed to strike a balance among the following properties: high Verdet constant, chemical and physical stabilities, compatibility with the fiber drawing process, and the connectivity to the silica glass fiber networks. In this work, we report on the MO application of Tb2O3‐Al2O3‐SiO2‐B2O3 (TASB) glasses as a derivative of the yttrium aluminum silicate (YAS) glass fiber systems which have been intensively studied for their huge potential in the context of all‐fiber lasers. We found that MO properties of the obtained TASB glasses vary systematically with the B2O3 contents. The effects of B2O3 on the local glass structures and the valence state of Tb ions were clarified via nuclear magnetic resonance, electron spin resonance, X‐ray photoemission spectroscopy, and Raman spectroscopy. B2O3 content in TASB glasses leads to a certain degree of depolymerization in glass network and most of Tb4+ ions from the raw material of Tb4O7 are reduced to Tb3+ ions even in air, resulting in an improved MO properties. Due to the relatively high Verdet constant (∼70 rad/T/m) and suitable rheology of the glass melt speculated from the thermal analysis, TASB glass system in this work is adaptable to stable fiber‐based Faraday effect devices. [ABSTRACT FROM AUTHOR]

Transparent polycrystalline ceramics (TPCs) are crystalline materials with single‐crystal‐like transparency, which, however, have to rely on fabrication processes with a relatively high cost. Here, we produced lab‐scale TPCs based on the typical refractory Y2O3‐Al2O3 system, through full congruent crystallization of the parent glass prepared by aerodynamic levitation melting method. Doping of the glass and TPCs by rare‐earth (RE) ions (Ce3+, Tb3+, Nd3+, and Yb3+) and transition‐metal (TM) ions (Cr3+) results in strong visible and near‐infrared (NIR) photoluminescence with high quantum yield. The dominance of Stark splitting of the emission band for RE and TM ions in the TPCs as compared with that of the glass confirms crystallization of the parent glasses. [ABSTRACT FROM AUTHOR]

Fluorescent detection is a new spectroscopic measurement for ions sensing due to the advantages of real‐time determination with high selectivity, accuracy, and low cost. However, chemosensors based on fluorescent detection are usually determined by absolute intensity from a monochromatic emission signal, which is easy to be fluctuated by the external environment, especially for Fe3+ detection in complex fluids. Herein, we rationally design a dual‐emission Eu3+: CDs@ZIF‐8 to construct a ratiometric fluorescent sensor with self‐calibrating ability for Fe3+ determination. High efficient carbon dots (CDs) are embedded in europium ions (Eu3+)‐doped MOF by simple stirring preparation at room temperature. The label‐free ratiometric fluorescent probe (ICDs@ZIF‐8/IEu) exhibits simultaneous blue and red emission under the same excitation at 365 nm. Remarkably, Eu3+: CDs@ZIF‐8 displays the superiority of high selectivity to Fe3+, which shows ratiometric fluorescence characteristics (I0/I) in a range of 0‐6 μmol\L with a low limit of detection (LOD) of 0.897 μmol\L. Besides, the CDs‐MOF nanocomposite holds good aqueous dispersibility and low cytotoxicity, which shows great potential applications in medical aid including biological detection and clinical diagnosis. [ABSTRACT FROM AUTHOR]

The application of graphitic carbon nitride (g‐C3N4) has been restricted in some optoelectronics fields due to its narrow tunable emission region. In order to engineer the optical properties, herein we combine Eu3+:Y2O3 nanocrystals with g‐C3N4to control its electronic structure. Surprisingly, with the increasing concentration of Eu3+:Y2O3 nanocrystals, the photoluminescence of Eu3+:Y2O3/g‐C3N4 (EYCN) showed a continuous red shift in comparison with pure g‐C3N4 from blue to green. In EYCN composites, the Eu3+:Y2O3 nanocrystals as electron donors, can improve the degree of electron delocalization and narrow the bandgap. Importantly, the EYCN composites not only maintain the intrinsic blue‐green emission of g‐C3N4, but also introduce the red light of Eu3+ ions. Based on the EYCN composites, white light‐emitting diode (WLED) were fabricated with a Commission International de L'Eclairage value of (0.3631, 0.3560). This work proposes a new kind of luminescent g‐C3N4‐based composites, which is expected to broaden its applications in optoelectronics field. [ABSTRACT FROM AUTHOR]

Tetra‐valent manganese (Mn4+) has been regarded as an efficient non‐rare‐earth red‐light emitting ion, which has stimulated continued search of robust hosts and efficient synthetic methods to stabilize Mn4+ centers with strong photoluminescence. In this work, we demonstrate a facile synthetic method for Mn4+ doped glass‐ceramic (GC) based on crystallization‐induced oxidation state change in an oxide glass. The parent glass with a formula of LiNaGe4O9 is fabricated by melt‐quenching and crystallization is induced by thermal treatment in air. Oxidation of Mn2+ in glass to Mn4+ in the GC is confirmed by both optical spectroscopy and electron paramagnetic resonance (EPR) measurements. After thermal treatment, the characteristic reddish photoluminescence (PL) of Mn2+ in the glass centered at 611 nm disappears and a strong photoluminescence peak at 660 nm attributed to Mn4+ is observed. The conversion to Mn4+ after crystallization in the examined system may have strong implications for synthesis of Mn4+ doped phosphors which always requires rigorous control of the redox equilibrium during synthesis. [ABSTRACT FROM AUTHOR]

Rare earth (RE) ions‐doped luminescent nanocrystals (NCs) with numerous unique advantages have attracted tremendous interest for the wide applications from science to engineering, yet suffering from the shortcoming of thermal quenching coming from surface organic ligands. We propose utilizing a facile acid‐base reaction to remove surface organic ligands introduced choosing carboxylic acids as stabilizing agent and weaken thermal quenching. The results showed that the acid‐base reaction displayed an outstanding cleaning effect. After acid‐treatment, most surface organic ligands were removed, and there was no influence on crystal structure and morphology of as‐prepared β‐NaYF4:Er3+ NCs. Meanwhile, with no surface organic ligands capping, β‐NaYF4:Er3+ NCs preferred brighter emission after thermal treatment, including up‐conversion (UC), near‐infrared (NIR), and mid‐infrared (MIR) emission. When calcined the acid‐treated β‐NaYF4:Er3+ NCs in different atmosphere, such as oxygen and reducing atmosphere (15%H2 + 85%N2), an unexpected enhancement of all emission bands in Er3+ was determined under phase transformation temperature, especially in oxygen atmosphere. Furthermore, all the fluorescence lifetimes of Er3+ also exhibited obvious extension. Our results supposed that the β‐NaYF4:Er3+ NCs have promising applications in safety ink, and the acid‐treatment by diluted hydrochloric acid is a general approach to remove deleterious organic ligands on NC surface further to weaken thermal quenching. [ABSTRACT FROM AUTHOR]

Due to the widely tunable band gap and broadband excitation, CdS quantum dots (QDs) show great promise for yellow‐light luminescence center in white‐light‐emitting devices. The light intensity of the CdS QD‐doped glass was enhanced by doping the Tm3+ ions due to the higher absorption rate. The influence of Tm3+ ions on the surface structure of CdS QDs was enormous according to the first‐principles calculations. Doping Tm3+ ions change the surface state of CdS QDs, which will fix the QDs emission peaks and enhance the luminescence of CdS QDs at a lower heat‐treatment temperature. White‐light emission was obtained by tuning the relative concentration between Tm3+/CdS QDs. However, there is a fundamental challenge to fabricate QD‐doped glass fibers by rod‐in‐tube method since uncontrollable QDs crystallization is hard to avoid. Herein, a white‐light‐emitting borosilicate glass fiber was fabricated by the "melt‐in‐tube" method using a special designed Tm3+/CdS QDs co‐doped borosilicate glass with low‐melting temperature as fiber core. After heat treatment, ideal white‐light emission was observed from the fiber under excitation at single wavelength (359 nm). This finding indicates that Tm3+/CdS QDs co‐doped glass fiber with white‐light‐emitting devices has potential application as gain medium of white‐light‐emitting sources and fiber lasers. [ABSTRACT FROM AUTHOR]

PbS quantum dot (QD)‐doped glasses were fabricated through melt‐quenching method. After heat treatment schedule, uniform QDs were precipitated in the glasses and near‐infrared emission covering 900‐1700 nm was obtained under excitation. From photoluminescence (PL) spectra and lifetime decay curves, the whole emission band of QD‐doped glasses consisted of emission from the 1S‐1S state and the trap state. While using excitation with higher energy, the full width at half maximum (FWHM) of QD‐doped glasses broadened because smaller QDs were excited. Energy transfer process among QDs was revealed by measuring the lifetime of different emission bands in PL spectrum and the energy transferred from smaller QDs with broader bandgap to bigger QDs with narrow bandgap. Temperature‐dependent PL and the corresponding lifetime decay curves of PbS QD‐doped glasses were analyzed. Temperature‐dependent bandgap structure of PbS QDs was obtained by using density functional theory (DFT) calculations. The results here give deep insight into optical properties of PbS QD‐doped glasses and it is beneficial to design and develop high‐performance QD‐based optoelectronic devices in theory. [ABSTRACT FROM AUTHOR]

The multi‐component glass fibers have demonstrated their unique advantages in the application of single‐frequency lasers due to their higher solubility of rare‐earth ions and thus a higher gain per unit length in a compact fiber laser cavity. In this study, multi‐component yttrium aluminosilicate (YAS) fiber with high doping concentration of Yb3+ was prepared by the "melt‐in‐tube" (MIT) method. A unit‐length gain of 3 dB/cm was obtained in a 4.4 cm‐long YAS fiber, the laser output slope efficiency reached 23.8% in a 10 cm‐long Yb:YAS fiber. Single‐frequency laser operation was achieved in a 1.7‐cm‐long Yb:YAS active fiber. To the best of our knowledge, this is the first demonstration of single‐frequency laser with this YAS glass fiber as gain medium. The novel multi‐component YAS fiber can be applied as a new gain material to realize single‐frequency fiber laser. [ABSTRACT FROM AUTHOR]

Abstract: Yttrium aluminosilicate (YAS) glass core fibers with different doping concentration of Tm3+ were fabricated by a “Melt‐in‐Tube” method from YAG polycrystalline ceramics. The effect of Tm3+ concentration on the spectroscopy of YAG ceramics and laser performance of YAS fibers were discussed. A homemade linear all‐fiber laser based on the obtained 15% Tm3+‐doped YAS fiber shows an optimized slope efficiency of 12.8%. The YAS fibers have been proven to be practical to achieve extremely high Tm3+ doping concentration and are a promising option for the 2.0 μm laser. [ABSTRACT FROM AUTHOR]

Abstract: It is well recognized that a widely wavelength‐tunable mid‐infrared (MIR) fiber laser plays an important role in the development of compact and efficient coherent sources in the MIR range. Herein, the optimizing Er/Ho ratio for enhancement of broadband tunable MIR emission covering 2.6‐2.95 μm in the Er3+/Ho3+‐codoped transparent borosilicate glass‐ceramic (GC) fibers containing NaYF4 nanocrystals under 980 nm excitation was investigated. Specifically, the obtained GC fibers with controllable crystallization and well fsd‐maintained structures were prepared by the novel melt‐in‐tube approach. Owing to the effective energy transfer between Er3+ and Ho3+ after crystallization, the 2.7 μm MIR emission was obviously enhanced and the emission region showed a notable extension from 2.6‐2.82 μm to 2.6‐2.95 μm after the addition of Ho3+. Importantly, we conducted a theoretical simulation and calculation related to the MIR laser performance, signifying that the GC fiber may be a promising candidate for MIR fiber laser. Furthermore, the melt‐in‐tube approach will provide a versatile strategy for the preparation of diverse optical functional GC fibers. [ABSTRACT FROM AUTHOR]

Abstract: In this paper, we report upconversion (UC) luminescence enhancement in LaBGeO5:Yb3+, Er3+ glass‐ceramics (GCs), surface crystallized glass‐ceramics (SCGCs) and ceramics compared with the as‐melt glass fabricated by the conventional melt‐quenching technique. Based on structural investigations, we find that the nucleation and crystallization of trigonal stillwellite LaBGeO5:Yb3+, Er3+ nanocrystals occur first at the glass surface before the following volume crystallization. The local site symmetry around rare earth (RE) ions which was evaluated using the Eu3+ ions as a probe together with Judd‐Ofelt theory calculations exhibits a clear increase with the devitrification of the glass. Consequently, complete crystallization of the glass leads to largest enhancement in the UC emissions of the LaBGeO5:Yb3+, Er3+ ceramics. We ascribe the enhancement of UC luminescence in the LaBGeO5:Yb3+, Er3+ GCs, SCGCs, and ceramics to the structural ordering and the improvement of site symmetry surrounding RE ions that minimizes the rate of nonradiative relaxation process. [ABSTRACT FROM AUTHOR]

Abstract: Borosilicate glasses doped with PbSe quantum dots (QDs) were prepared by a conventional melt‐quenching process followed by heat treatment, which exhibit good thermal, chemical, and mechanical stabilities, and are amenable to fiber‐drawing. A broad near infrared (NIR) photoluminescence (PL) emission (1070‐1330 nm) band with large full‐width at half‐maximum (FWHM) values (189‐266 nm) and notable Stokes shift (100‐210 nm) was observed, which depended on the B2O3 concentration. The PL lifetime was about 1.42‐2.44 μs, and it showed a clear decrease with increasing the QDs size. The planar [BO3] triangle units forming the two‐dimensional (2D) glass network structure clearly increased with increasing B2O3 concentration, which could accelerate the movement of Pb2+ and Se2− ions and facilitate the growth of PbSe QDs. The tunable broadband NIR PL emission of the PbSe QD‐doped borosilicate glass may find potential application in ultra‐wideband fiber amplifiers. [ABSTRACT FROM AUTHOR]

Abstract: A graded‐index fiber with yttrium aluminosilicate (YAS) glass core was fabricated by a “Melt‐in‐Tube” method. The refractive index and stress profiles of the fibers exhibit a highly symmetrical gradient tendency along the radial axis which is in accordance with the results of element migration. Based on the formation mechanism of YAS glass core, the relationships between the refractive index/stress profile and the spontaneous migration are discussed. A linear all‐fiber laser based on the obtained fiber shows a laser output threshold of 11.48 mW and slope efficiency of 8.3%. The near‐field beam intensity distribution of fiber laser with spectrum FWHM of 0.24 nm indicates the good laser beam quality. The facile “Melt‐in‐tube” method was proved to be reliable in designing graded‐index fiber through the dissolution and diffusion process, which is more advanced than commonly used “Rod‐in‐tube” method. [ABSTRACT FROM AUTHOR]

Abstract: A novel non‐rare‐earth doped phosphor La2MgGeO6:Mn4+ (LMG:Mn4+) with near‐infrared (NIR) long persistent luminescence (LPL) was successfully synthesized by solid‐state reaction. The phosphors can be effectively excited using ultraviolet light, followed by a sharp deep‐red emission peaking at 708 nm, which is originated from 2Eg → 4A2g transition of Mn4+ ions. The luminescent performance was analyzed by photoluminescence (PL) and photoluminescence excitation (PLE) spectra. The crystal field parameters were calculated to describe the environment of Mn4+ in LMG host. The LPL behaviors as well as the mechanisms were systematically discussed. This study suggests that the phosphors will broaden new horizons in designing and fabricating novel NIR long phosphorescent materials. [ABSTRACT FROM AUTHOR]

We fabricated a series of stable Er-doped CaO-Al2O3(Ga2O3) glasses by aerodynamic levitation (ADL) method. Using thermal analysis, we studied the influence of composition on the thermal stability of the glasses. The results unraveled the significance of composition on the stability of glasses. Magic angle spinning nuclear magnetic resonance (MAS-NMR) and Raman spectra were used to analyze the glass microstructure. The optical and spectroscopic properties were examined by UV-Vis absorption, steady-state fluorescence spectroscopy, transient state fluorescence spectroscopy, and luminescence quantum yield measurements. The results unraveled a clear concentration-dependent up-conversion and NIR emissions of Er3+, with obvious spectral broadening and redshift. The related mechanisms of decrease in fluorescent lifetime (from about 9 ms to 2 ms) and quantum yield (from about 75% to 5%) are discussed. [ABSTRACT FROM AUTHOR]

The fabrication and near-infrared optoelectronic performance of the (Na YF4:Yb-Er)/Bi OI upconversion phosphor/semiconductor hybrid films are reported. The composite films were fabricated by a simple electro-deposition and successive ionic layer adsorption and reaction ( SILAR) method. We observed efficient upconversion emissions in the film of Na YF4:Yb-Er upon irradiation by near-infrared part of simulated sunlight, and the UC emission is drastically quenched in the composite film (Na YF4:Yb-Er)/Bi OI. More importantly, this composite film displays unusual negative photoresponse to near-infrared part of simulated sunlight when used in a standard electrochemical cell where the composite film serves as the photoanode. This result may pave the way for potential application of this hybrid films for the development of novel photovoltaic and infrared optoelectronic devices. [ABSTRACT FROM AUTHOR]