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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 rapid development of emerging technologies observed in recent years, such as artificial intelligence, machine learning, mobile internet, big data, cloud computing, and the Internet of Everything, are generating escalating demands for expanding the capacity density, and speed in next‐generation optical communications. This poses a significant challenge to existing communication techniques. Within this context, the integration of near‐infrared broadband, tunable, and high‐gain luminescent materials into silicon optical circuits or fiber architectures to transmit and modulate light shows enormous potential for advancing next‐generation communication techniques. Here, this review provides an overview of the recent breakthroughs in near‐infrared luminescent epitaxial/colloidal quantum dots, and metal‐active‐center‐doped materials for broadband optical amplifiers and tunable lasers. We also expound on efforts to enhance the bandwidth and gain of these materials‐based amplifiers and lasers, exploring the challenges associate with developing ultra‐broadband and high‐speed optical communication systems. Additionally, the potential applications in Fifth Generation Fixed Networks, integration with 5G and 6G wireless networks, compensation for current Si electronic based CMOS for high computing capability, and the prospects of these light sources for next‐generation optoelectronic devices are discussed. [ABSTRACT FROM AUTHOR]

Lanthanide doped nanoparticles (NPs) exhibit tunable X‐ray‐excited optical luminescence and X‐ray‐excited persistent luminescence (XEPL), holding broad prospects for applications in display/anti‐counterfeiting and X‐ray imaging. The development of effective strategies for multi‐dimensional applications based on lanthanide‐doped fluoride NPs are a constant challenge. Here, core–shell structured fluoride NPs, in which the heavy metal fluoride shell effectively suppresses the non‐radiative relaxation and simultaneously improve the X‐ray absorption of the shell are designed and fabricated. Under X‐ray irradiation, the developed NPs exhibit an increased number of secondary electrons which migrate to Er3+ centers at the interface and greatly improve the XEPL intensity. Additionally, the introduction of Mn2+ further enhances the XEPL intensity and offers an effective route to control the red‐green ratio of the upconversion spectrum. The NPs co‐doped with Mn2+ exhibit a bright green XEPL under X‐ray irradiation and a red emission under 1532 nm laser excitation. It is further validated that these NPs can be utilized for advanced anti‐counterfeiting and high‐resolution delayed imaging based on a film containing NPs as a scintillation screen. These findings suggest a new strategy of designing Er3+ doped NPs for multi‐dimensional applications. [ABSTRACT FROM AUTHOR]

Phosphor‐converted light‐emitting diodes (pc‐LEDs) are efficient and cost‐effective ultrabroadband light sources for miniaturizing various optical systems, but they exhibit poor optical performance due to the lack of efficient near‐infrared (NIR) phosphors with a wide spectral coverage of 700−1100 nm. Although germanate oxides are a promising class of host materials for Cr3+ to generate broadband NIR light, the preferred formation of [CrO4]4− and the high vapor pressure of Ge element cause these Cr3+ activated phosphors to suffer from low internal quantum efficiency (IQE) and poor thermal stability. Here, highly efficient (IQE > 90%) and thermally stable broadband NIR emission of Cr3+ in the germinate garnet Ca2LuMgScGe3O12 (CLMSG) are obtained by exploiting a two‐step sintering method to achieve full reduction of Cr4+ to Cr3+. Further, efficient energy transfer from Cr3+ to Yb3+ is leveraged to significantly improve the emission intensity of CLMSG:Cr3+ in the shortwave infrared range of 900−1100 nm. Finally, an ultrabroadband NIR pc‐LED with a high NIR conversion efficiency (21.5%@10 mA) and high NIR power (116.4 mW@350 mA) is demonstrated to verify the strong capability of CLMSG:Cr3+, Yb3+ in blue‐to‐NIR light conversion. The results open up new ways to realize efficient ultrabroadband NIR‐emitting materials. [ABSTRACT FROM AUTHOR]

Long persistent luminescence materials (LPLMs) are promising candidates for various photonic applications, owing to their ability to store light. In spite of advancements in exploring of new LPLMs, the fabrication of transparent centimeter‐sized LPLMs with pre‐designed shapes, high productivity, long afterglow multicolor luminescence, and high chemical stability, is still challenging. Here, high‐throughput manufacture of translucent crystal‐glass composites via a classical injection molding (IM) technique is demonstrated, in which persistent phosphors (PPs)‐amorphous silica nanoparticles‐polymer composites are molded into different shapes then thermally treated at elevated temperatures to obtain glass composites with embedded PP particles and customized shapes. The structural characterizations endorse that the PP particles are preserved during high temperature sintering, and the resultant crystal‐glass composites combine the unique benefits of both PPs and silica glass. Remarkably, the total production time to manufacture 100 pieces of centimeter‐sized crystal‐glass composites is 35 h, thus enabling high‐throughput production of glass composite articles by the IM method. In addition, the injection molded crystal‐glass composites demonstrate long afterglow multicolor luminescence and ultrahigh chemical durability. This study provides a massive production strategy for the fabrication of translucent and stable multicolor persistent luminescent objects with customized shapes, which can be used in numerous applications. [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]

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]

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]

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]

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]

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]

Effective online monitoring of the spatial distribution of high‐energy radiation is of significant importance in various fields such as medical imaging, high‐energy physics, and homeland security. However, achieving radiation detectors with both high sensitivity and minimal disturbance is an enormous challenge. The present study introduces a solution to this bottleneck issue through the development of a full‐inorganic scintillating fiber, successfully demonstrating its application in constructing a radiation monitoring device. The scintillating fiber, activated with Ce3+ and fabricated using the melt‐in‐tube approach, is lightweight with a density of 2.5 g cm−3 and exhibits efficient scintillating emission with a light yield of 4000 photons MeV−1. These characteristics enable the achievement of radiation detection with high sensitivity while keeping disturbance to the incident radiation beam at a minimum. Furthermore, 2D and 3D radiation beam monitors are constructed based on these scintillating fibers, facilitating spatial radiation monitoring. The findings demonstrate that full‐inorganic scintillating fibers and devices offer a synergistic combination of high sensitivity and negligible disturbances. This progress not only introduces a novel full‐inorganic fiber for radiation detection but also suggests promising applications in various nuclear fields where 3D radiation beam tracking is essential. [ABSTRACT FROM AUTHOR]

Oxyfluoride transparent glass‐ceramics (GC) are widely used as the matrix for rare‐earth (RE) ions due to their unique properties such as low phonon energy, high transmittance, and high solubility for RE ions. Tb3+ doped oxyfluoride glasses exhibit a large absorption cross section for ultraviolet (UV) excitation, high stability, high photoluminescence quantum efficiency, and sensitive spectral conversion characteristics, making them promising candidate materials for use as the spectral converter in UV photodetectors. Herein, a Tb3+ doped oxyfluoride GC is developed by using the melt‐quenching method, and the microstructure and optical properties of the GC sample are carefully investigated. By combining with a Si‐based photo‐resistor,a solar‐blind UV detector is fabricated, which exhibits a significant photoelectric response with a broad detection range from 188 to 400 nm. The results indicate that the designed UV photodetector is of great significance for the development of solar‐blind UV detectors. [ABSTRACT FROM AUTHOR]

The precise manipulation of neural activity is of great significance to reveal the function of complex neural circuits in brain, especially the mechanism of neurological disorders such as epilepsy, Parkinson's, and Alzheimer's disease. In the past decades, optogenetics has become a powerful tool to investigate the function of neural circuits due to its unique advantages of cell specificity and high spatiotemporal resolution. However, to date, most optogenetic manipulation has been conducted in an open‐loop fashion. The closed‐loop neural modulation is still an important task. Here, a closed‐loop optogenetic modulation system is developed for ultra‐fast, ‐accurate, and ‐stable manipulation of neural activities in behaving mice. Specifically, this system is mediated by a functional fiber probe with excellent low optical loss (0.052 dB cm−1 at 589 nm) and electrical impedance (5.40 MΩ µm−2 at 1 kHz). In vivo electrophysiology and behavioral experiments demonstrated that the system can be successfully applied for the identification and intervention of seizures in epilepsy mice with high efficiency. It is envision that the closed‐loop manipulation system has promising applications in brain science, neuroscience, and neuromodulation therapies. [ABSTRACT FROM AUTHOR]

In the digital era, the need for high‐density data storage techniques has become increasingly imperative. To address this, the study has demonstrated a multi‐dimensional shingled optical recording technique, utilizing femtosecond laser‐induced nanostructures in silica glass. The evolution of the bulk nanostructures is investigated on a pulse‐by‐pulse basis using multiple microscopic analysis techniques. The formation of the nanostructures is attributed to a self‐adaptive near‐field anisotropic nanostructuring process. Furthermore, it is shown that writing in a 3D shingled configuration significantly reduces the volume per data voxel to a size of 500 nm × 500 nm × 1.0 µm, surpassing the diffraction limit. This reduction is achieved even when employing an infrared laser and a relatively low numerical aperture objective lens. As a result, the approach increases the data storage capacity by at least two orders of magnitude compared to conventional techniques. The work paves the way for advanced shingled optical recording techniques offering ultra‐dense capacity, ultra‐long lifetime, and low energy consumption. [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]

With the rapid development of 5G networks, the Internet of Things, and new‐generation of AI, there are considerable demands on expanding the capacity of contemporary optical fiber communication systems. One of the most effective avenues involves the extension of the bandwidth of Er‐doped fiber amplifiers, but with limited success. Herein, an Er‐activated hybridized glass fiber are reported, which can help realize broadband telecommunication. The effect of element hybridization on the bandwidth of Er‐activated fiber is clarified and the structure‐optical response relationship is established. A two‐step deposition approach is proposed to overcome the immiscibility barrier of different hybridized elements, and Er‐activated fiber with uniform doping is constructed. The activated fiber presents excellent compatibility with commercial telecommunication systems, providing a small signal gain of >13 dB in the whole L‐band range and a maximum gain of 28 dB. Furthermore, the Er‐activated fiber amplifier device is successfully developed. It exhibits outstanding optical amplification performance with gain >24 dB in the range of 1580–1624 nm, gain fluctuation less than ±0.9 dB, and noise figure <6.5 dB. The results not only provide a new strategy for developing novel active broadband optical fibers, but a valuable solution for new‐generation large‐capacity optical fiber communication systems. [ABSTRACT FROM AUTHOR]

Laser‐induced periodic surface structure (LIPSS) can form structural color on the metal surfaces with high production efficiency and thermal stability, and has been used in various industrial applications such as unfaded color marking and anti‐counterfeiting. Herein, a novel fabrication scheme of multilayer LIPSS is proposed by multiple writing in situ with changing the laser polarization direction, to exhibit an effect of color superposition. To verify this approach, the color formation mechanism of LIPSS on the stainless‐steel surface is analyzed by finite‐element numerical calculation and reveals that the high‐angular dispersion of LIPSS is mainly the result of optical diffraction occurring on the surface of periodic structures. The relationship between the angular dispersion of multilayer LIPSS and laser‐processing parameters is established. Through the proposed multilayer LIPSS coloring technology, vivid full‐color patterns on the steel surface are demonstrated, and the in situ superposition of three‐layer graphs is realized, which can greatly enrich the color levels and be competitive in industrial applications. [ABSTRACT FROM AUTHOR]

Excitation polarized upconversion luminescence (EPUL) from lanthanide ions has attracted considerable attention due to its wide applications in microfluidics, single particle tracking, security inks, and cell internal viscosity testing. However, controlling the degree of excitation polarization (DOEP) of the EPUL remains a significant challenge. Here, the modulation of the DOEP (from 0 to 0.5) of the EPUL from Er3+ doped single nanorods by changing the concentration of doped Er3+, Yb3+, or Mn2+ is systematically studied. By analyzing the lifetimes and disproportionate changes in luminescence intensities, it is found that optimizing Er3+, Yb3+, or Mn2+ concentration can reduce non‐radiative transition and population density in excited states, leading to the enhancement of the DOEP under a good alignment of transition dipoles. Furthermore, the possibility of anti‐counterfeiting based on such tunable EPUL is illustrated. Three kinds of fine patterns with a small size of 10 µm are realized by assembling the single nanorods accurately via optical tweezers. The patterns and their EPUL guarantee double protection for the feasibility of anti‐counterfeiting. The findings of this study offer insights into the EPUL from lanthanide ions and provide a microscale platform via the EPUL for the application of multidimensional information encoding and reconfigurable double anti‐counterfeiting. [ABSTRACT FROM AUTHOR]

Wavelength conversion based on hybrid inorganic–organic sensitized triplet–triplet annihilation upconversion (TTA‐UC) is promising for applications such as photovoltaics, light‐emitting‐diodes, photocatalysis, additive manufacturing, and bioimaging. The efficiency of TTA‐UC depends on the population of triplet excitons involved in triplet energy transfer (TET), the driving force in TET, and the coupling strength between the donor and acceptor. Consequently, achieving highly efficient TTA‐UC necessitates the precise control of the electronic states of inorganic donors. However, conventional covalently bonded nanocrystals (NCs) face significant challenges in this regard. Herein, a novel strategy to exert control over electronic states is proposed, thereby enhancing TET and TTA‐UC by incorporating ionic‐bonded CsPbBr3 and lanthanide Ce3+ ions into composite NCs. These composite‐NCs exhibit high photoluminescence quantum yield, extended single‐exciton lifetime, quantum confinement, and uplifted energy levels. This engineering strategy of electronic states engendered a comprehensive impact, augmenting the population of triplet excitons participating in the TET process, enhancing coupling strength and the driving force, ultimately leading to an unconventional, dopant concentration‐dependent nonlinear enhancement of UC efficiency. This work not only advances fundamental understanding of hybrid TTA‐UC but also opens a door for the creation of other ionic‐bonded composite NCs with tunable functionalities, promising innovations for next‐generation optoelectronic applications. [ABSTRACT FROM AUTHOR]

Higher‐order corner‐bound states in a 2D structure have been found to possess robust and exotic properties beyond the "ordinary" topological edge states, giving rise to a promising applicative potential. For example, the topological nanocavity designed based on the corner states exhibits much better performance than that of the conventional photonic crystal cavity. However, the corner states in the finite Hermitian system are usually coupled with each other, which results in the weakening of their localization. As such, the contradiction between the performance and footprint of topological devices is vexing. Here, it shows that introducing non‐Hermiticity in the higher‐order topological insulators is an effective strategy to enhance the localization of corner states in finite systems. By designing and analyzing the 2D finite Su‐Schriffer‐Heeger optical lattices with two types of non‐Hermitian configuration, the localization degree of higher‐order corner states is found to depend on the gain/loss strength. This is experimentally demonstrated by observing the distribution of corner states in the femtosecond‐laser‐writing loss‐controlled waveguide arrays. This scheme tuning localization of higher‐order corner‐bound states by non‐Hermiticity may offer a new avenue to design robust and compact devices, such as topological nano‐lasers with an ultra‐low threshold. [ABSTRACT FROM AUTHOR]

The outstanding performance of halide perovskite makes it one of the champion materials for applications in optoelectronic devices. However, the stability of perovskites limits their practical applications. Among all the factors influencing the stability of perovskites, defects are one of the key factors. Till now, many chemical methods have been proposed to passivate defects. Nevertheless, there is still a lack of in situ passivation methods without the change of the composition of perovskites. Here, it is found that the external electric field can passivate the defects in FPEA2PbI4 (FPEAI = 2‐(4‐Fluorophenyl)ethylamine Hydroiodide) film in a capacitive device at 78 K, and the PL intensity can be enhanced greatly. A "charge‐soaking effect" can be observed, that is PL intensity continues to increase for a long time after removing the electric field. Besides the emission peak from free exciton, two other peaks at the lower energy side from defect‐bound excitons are observed. They are more susceptible to the external electric field than the free exciton. This work will deepen the understanding of exciton behavior and the interaction of electric field with excitons in two–dimensional (2D) hybrid perovskites for efficient light–emitting diodes (LEDs) and electrically pumped lasers. It provides a new in situ passivation method of perovskites for practical applications. [ABSTRACT FROM AUTHOR]

Broadband near‐infrared (NIR) photonic materials have wide applications. Although extensive studies on rare‐earth, transition‐metal, and even semiconductor‐activated materials have enabled the development of a rich NIR material pool, developing broadband and efficient photonic candidates covering the NIR I and II regions from 750 to 1500 nm has been met with limited success. Here, it is reported that a subnano Te cluster with a characteristic configuration different from that of the ion state may fill the aforementioned gap. Further, a strategy is proposed for the in situ generation and stabilization of Te clusters by tuning the cluster evolution in glass. A novel active photonic glass embedded with a Te cluster is fabricated; it exhibits intense and broadband short‐wave NIR luminescence with a central wavelength at 1030 nm and a bandwidth exceeding 330 nm. Interestingly, the glass exhibited a full visible‐spectrum conversion ability from 300 to 800 nm. The application of this unique broadband excitation feature for night vision and tissue penetration is demonstrated using a smartphone as the excitation source. These findings demonstrate a fundamental principle of cluster design in glass for creating new properties and provide a new direction for developing novel cluster‐derived functional composite materials. [ABSTRACT FROM AUTHOR]

Real‐time investigation in mode‐locked fiber lasers (MLFLs) is important to understand the ultrafast dynamics before, during, and after the formation of stable laser pulses. However, the experimental measurement of these dynamics is restricted by the resolution of conventional oscilloscopes. The development of a time‐stretched dispersive Fourier transform (TS‐DFT) technique provides the shot‐to‐shot measurement of mapping the spectral information of an ultrashort optical pulse into time‐stretched waveform in the MLFL. Here, the recent progress and development of various fascinating dynamics in the MLFL, including the study of birth, evolution, and extinction process in MLFL, different types of MLFL, and complex motion dynamics in MLFL, have been reviewed. The issues and challenges encountered in this research area are discussed and several recommendations are suggested to overcome these problems. The integration of the TS‐DFT technique is expected to provide deeper insight into the real‐time investigation of various dynamics in the MLFL by displaying fascinating phenomenon and revealing unexplored trajectories. [ABSTRACT FROM AUTHOR]

Owing to the forthcoming global energy crisis, the search for energy‐saving materials has intensified. Over the past two decades, mechanically induced luminescent materials have received considerable attention as they can convert waste into useful components, for instance, the conversion from stress into light. However, this material features many constraints that limit its widespread application. Herein, a strategy to improve the mechanoluminescence (ML) of ZnO by embedding it in a ZnF2:Mn2+ matrix is introduced. Upon dynamic excitation via an external stress, the reddish‐yellow ML is confirmed to originate from the 4T1 (4G) → 6A1 (6S) transition of the optically active Mn2+ center. Moreover, the sample with the strongest ML contains the appropriate amount of ZnF2 (ZnF2:ZnO = 7:3). By performing density functional theory calculations, a possible ML‐enhancement mechanism is elucidated, which indicates the formation of a ZnF2/ZnO:Mn2+ heterojunction. Considering the unique characteristics of ML, its promising applications are demonstrated in various mechano‐optics scenarios, including flexible and stretchable optoelectronics, advanced self‐powered displays, e‐skins/e‐signatures, and anti‐counterfeiting, without the use of external light/electric‐incentive sources. The study significantly increases the variety of ML materials and is expected to strengthen the foundation for the future development of smart mechanically controlled devices and energy‐saving systems. [ABSTRACT FROM AUTHOR]

The fabrication of multicolor luminescent glass with simultaneous controlling of the distribution of emission colors within a monolithic medium has been a tremendous challenge, which, however, could be attractive for diverse photonic applications from optical storage to information encryption. Here, a space‐selective doping method based on a stereolithographic technique is designed, enabling the control of the doping domain of the active luminescence ions, such as Eu3+, Ce3+, Tb3+, and Pr3+, in 3D‐printed single silica glasses. The printed glass shows intense multicolor luminescence, and the interface between the two doping areas is invisible under natural light. By using this technique, multicolor luminescent glass with pre‐designed emission color distribution is fabricated, which enables facile and nondestructive decryption strategies based on photoluminescence under controlled excitation conditions. Besides, the extending of this strategy by using a femtosecond laser for photopolymerization dramatically improves the printing resolution down to the few‐micron scale, enabling the multi‐dimensional optical storage and encryption in miniaturized glass items. This work not only delineates the potential applications of multicolor luminescent glass for multi‐dimensional anti‐counterfeiting and information storage, but also opens up new avenues for prospective applications in sensing, lasers, and displays based on glasses with spatially engineered optical responses. [ABSTRACT FROM AUTHOR]

Bismuth (Bi)‐doped glasses with broadband near‐infrared (NIR) emission have been drawing increasing interest due to their potential applications in tunable fiber lasers and broadband optical amplifiers. Yet, the implementation of highly efficient and ultra‐broadband Bi NIR emission covering the whole telecommunication window remains a daunting challenge. Here, via a metal reduction strategy to simultaneously create a chemically reductive environment during glass melting and enhance the local network rigidity, a super broadband (FWHM ≈ 600 nm) NIR emission covering the entire telecommunications window with greatly enhanced intensity was achieved in Bi‐doped germanate glasses. More importantly, due to the excellent thermal stability, the super broadband Bi NIR emission can be well retained after the glass was drawn into an optical fiber. Furthermore, the transmission loss of 0.066 dB/cm at 1310 nm and an obvious broadband amplified spontaneous emission spectrum spanning a range of 1000–1600 nm were observed in this fiber. This work can strengthen our comprehension of the complicated Bi NIR luminescence behaviors and offer a feasible and universal way to fabricate tunable fiber lasers and broadband optical amplifiers based on Bi‐doped multicomponent glasses. [ABSTRACT FROM AUTHOR]

Bismuth(Bi)‐doped photonic materials with broadband near‐infrared luminescence can be used in applications such as high‐capacity fiber communication, fiber laser, and biological imaging. The scalable fabrication of Bi‐doped fibers with high dopant solubility, high optical activity, and broadband optical response still remains a significant challenge. In this study, the comprehensive studies on the physical, chemical, mechanical, and optical responses of a Bi‐doped glass system are performed and a Bi‐doped germanate multicomponent glass system is proposed to be the promising candidate. The deactivation mechanism of Bi in a glass matrix is investigated and prevented by controlling the fiber drawing. In addition, a Bi‐doped multicomponent germanate glass fiber with a high level of Bi doping is successfully constructed. Finally, a principle compact fiber amplifier device is fabricated for broadband optical amplification. This device can be potentially used for increasing the capacity of telecommunication systems. [ABSTRACT FROM AUTHOR]

Embedding naked‐eye‐invisible electronic and optical elements in transparent panels is at the heart of enabling mobile transparent accessories by making see‐through smart screens. Here, a novel invisible photonic element, highly see‐through (HST) waveguide, is reported, which is written by femtosecond laser in glass. A general synergistic control of the thermodynamic and dynamic behavior over the matter fluid in the laser irradiated confined region to tune the cross‐section of waveguides and suppress the generation of scattering centers in the waveguides is established. An effective reduction of light leakage (covering red, green, and blue coupled light) by an order of magnitude compared to conventional waveguides is achieved, making it highly see‐through at bright illumination of >100 lux. A general dynamical model based on a frozen‐in shock wave diffusion process is proposed, which is applicable to various glasses regardless of their compositions. Ultra‐wide tuning of HST waveguide mode diameters from 4.9 to 26.5 µm is demonstrated, making it versatile for functionalizing various transparent screens by mode‐matching with fiber sources and integrated planar waveguides of different working wavelengths. [ABSTRACT FROM AUTHOR]

Recently, higher‐order topological insulators (HOTIs), accompanied by topologically nontrivial boundary states with a codimension larger than one, have been extensively explored because of unconventional bulk‐boundary correspondences. As a novel type of HOTIs, very recent works have explored the square‐root HOTIs, where the topologically nontrivial nature of bulk bands stems from the square of the Hamiltonian. In this paper, 2D square‐root HOTIs are experimentally demonstrated in photonic waveguide arrays written in glass using femtosecond laser direct‐write techniques. Edge and corner states are clearly observed at visible light spectra. The dynamical evolutions of topological boundary states are experimentally demonstrated, which verify the existence of photonic corner states in two band gaps. The symmetry‐protected corner states in the photonic square‐root HOTI may have potential applications in information processing and lasing. [ABSTRACT FROM AUTHOR]

The pursuit of high‐resolution and advanced anti‐forgery technology has stimulated a growing demand for anti‐counterfeiting and encryption strategies with real‐time response and high security. Polarized patterns taking the advantage of high security, rapid response, simple operation, and great selectivity enable real‐time and non‐invasive detection by monitoring in different polarization directions. Here, a new strategy to design and fabricate the polarized CsPbBr3 quantum dot (QD) line arrays by femtosecond (fs) laser writing in a transparent glass matrix is proposed. The obtained line array structures endow isotropic CsPbBr3 QDs with macroscopic polarized emission with a polarization degree up to 0.189. Through programable design, the authors have created 2D and 3D polarized luminescent patterns made up of vertical and horizontal lines inside the glass for polarization‐sensitive optical anti‐counterfeiting patterns. The CsPbBr3 QD line arrays used in anti‐counterfeiting can be well maintained in the water environment. The successful demonstration of the laser writing CsPbBr3 QD polarization structures in glass highlights the versatility of anti‐counterfeiting and encryption. [ABSTRACT FROM AUTHOR]

Chemical engineering in lead halide perovskite nanocrystals (PNCs) has garnered significant attention for tailoring optoelectronic properties, such as bandgap, quantum yield (QY), and stability. Here, pure blue emissive PNCs in glass by using ultrafast laser are reported. The emission wavelength is tuned in the range from 461 to 520 nm by engineering the chemical composition in the B‐site Cd/Pb mix‐cation system. The photoluminescence (PL) QY of CsCdxPb1−xBr3 PNCs reaches 13.4% for the pure blue emission at 467 nm, which is twice that of CsPbBryCl3−y PNCs. The pure blue emissive PNCs exhibit remarkable stability when exposed to ultraviolet (UV) radiation, heat, and ethanol solvents. The ultrafast laser print patterns can be encrypted and decrypted for information, which shows great potential for crucial information security applications. These results imply that B‐site engineering for lead halide PNCs embedded in glass is effective to tailor the PL spectra and increase the PL QY. The pure blue emissive PNCs hold great potential in the applications of blue and full‐color emissive devices. [ABSTRACT FROM AUTHOR]

The ability to modulate the nonlinear optical (NLO) response of low‐dimensional metal oxides is highly desirable for diverse applications. It is shown here that the irradiation of a dispersion of 2D oxide (MoO3) nanosheets (NSs) by femtosecond laser pulses enables simultaneous scissoring of the NSs to form well‐dispersed MoO3 quantum dots (QDs) and the modulation of the NLO response in the visible and near‐infrared (NIR) regions. The inversion of the absorptive nonlinearity is observed combined with a larger enhancement of NLO response in the laser‐irradiated MoO3−x NSs and the as‐generated QDs, which is associated with the steady laser‐deprival of oxygen atoms and the resultant localized surface plasmon resonance due to electron doping. By leveraging the sub‐picosecond NLO response of the plasmonic MoO3−x QDs, the development of ultrafast optical switches is demonstrated for ultrashort pulse laser generation based on fiber lasers operating in the NIR regions. Furthermore, the strong field enhancement of these non‐noble metal plasmonic QDs is exploited for the fabrication of substrates for surface‐enhanced Raman scattering, which demonstrate a detection limit down to the part‐per‐billion level. This work delineates an efficient strategy for creating plasmonic oxide QDs with strong NLO response that is attractive for photonic applications. [ABSTRACT FROM AUTHOR]

Broadband near‐infrared (NIR) phosphors have recently received considerable attention in spectroscopy technology fields, but designing inexpensive, emission peaks centered above 800 nm, and multimodal broadband NIR luminescence material still remains a great challenge. Here, by selecting stannate compound Mg2SnO4 (MSO) as the host, a kind of broadband NIR phosphor MSO:Cr3+ with multimode luminescence properties is reported. The designed material exhibits an emission peaking at 800 nm and a full‐width at half maximum of 180 nm (≈2730 cm−1). The site occupation of Cr3+ in MSO is unraveled by density functional theory calculation. The constructed NIR light‐emitting device based on MSO:Cr3+ displays a high NIR output power of 187.19 mW@100 mA and remarkable photoelectric efficiency of 13.67%, and its multifunctional applications in information encryption, non‐destructive detection, and so on are also demonstrated. Additionally, through defect site reconstruction, MSO:Cr3+ presents superior broadband NIR persistent luminescence (PersL) properties with PersL duration time longer than 50 h. This work provides a feasible strategy to develop intelligent optical material integrated with multimodal luminescence through low‐cost stannate compounds as the host toward versatile applications such as non‐destructive detection and bioimaging. [ABSTRACT FROM AUTHOR]

Metal coordination compound (MCC) glasses [e.g., metal‐organic framework (MOF) glass, coordination polymer glass, and metal inorganic‐organic complex (MIOC) glass] are emerging members of the hybrid glass family. So far, a limited number of crystalline MCCs can be converted into glasses by melt‐quenching. Here, we report a universal wet‐chemistry method, by which the super‐sized supramolecular MIOC glasses can be synthesized from non‐meltable MOFs. Alcohol and acid were used as agents to inhibit crystallization. The MIOC glasses demonstrate unique features including high transparency, shaping capability, and anisotropic network. Directional photoluminescence with a large polarization ratio (≈47 %) was observed from samples doped with organic dyes. This crystallization‐suppressing approach enables fabrication of super‐sized MCC glasses, which cannot be achieved by conventional vitrification methods, and thus allows for exploring new MCC glasses possessing photonic functionalities. [ABSTRACT FROM AUTHOR]

Orthogonal upconversion nanoparticles (UCNPs) have received increasing research attention due to their unique optical performance. However, the establishment of the orthogonal UCNPs emitting primary red/green/blue (RGB) UCL remains a great challenge. Herein, RGB‐switchable NaErF4‐cored core–multishell UCNPs (RGB‐UCNPs) are constructed through the coordinative implementation of outside‐in cascaded photon harvesting and interfacial energy‐transfer (IET) inhibition. By modulating several constructional factors, the power‐density‐independent red, green, and blue luminescence in high color purity is readily available in the elaborated RGB‐UCNPs under 1550, 808, and 980 nm excitations, respectively. Notably, full‐color emissions, involving red, yellow, green, cyan, blue, magenta and white, are dynamically implemented in this single architecture through manipulating the excitation power of the combined 1550/808/980 nm lasers. These emission profiles of RGB‐UCNPs make them promising in broad photonic applications. As a proof of concept, the viability of the logicalized information encryption strategy and smartphone APP‐assisted multimodal luminescent QR code anti‐counterfeiting technique is demonstrated, which are both established based on directly useable RGB‐UCNPs with assistance of a self‐built combined laser system. This work not only opens up a new avenue to gain RGB‐switchable UCL and flexible full‐color output in a single nanostructure, but also provides enlightenment for developing the application scenarios of multicolor‐tunable UCNPs. [ABSTRACT FROM AUTHOR]

The ability for simultaneous modulation and monitoring of neural activities in deep tissues and at the single‐cell level merits significant scientific and technological potential, yet is met with limited success using conventional probes. Here, a new type of tiny multimaterial glass fiber probe is proposed and successfully constructed with the combination of robust mechanical response, strong light‐delivering ability, and excellent electrochemical properties, based on high throughput and scalable co‐drawing strategy. Guided by the multimaterial integration principle, the configuration of the probes can be rationally tuned including their material combination, physical size, the number and spatial distribution of the electrode, and even the waveguide structure. The bending stiffness, optical loss, and electrical impedance can be controlled to be larger than 4900 N m−1 and as small as 0.01306 dB cm−1 and 19.63 MΩ µm2 at 1 kHz, respectively. To prove the utility, it is demonstrated that the probes allow for simultaneous deep neural stimulation and detection for more than 2 weeks at a single cellular level. This work not only promotes the development of neuroscience and brain science through the ability to manipulate neural circuits in the deep brain but also provides new directions for expanding the scope of functional fibers. [ABSTRACT FROM AUTHOR]

High‐brightness phosphor‐converted solid‐state light (SSL) sources based on blue light‐emitting diodes (LEDs) or laser diodes (LDs) will enable versatile optical applications other than general illumination. However, luminescence ceramics/crystals are too expensive for widespread use, while phosphor‐in‐glass converters suffer from low conversion efficiency at high‐power‐density excitation and poor chemical and thermal stabilities of low‐melting glasses. Herein, an ultrathin interface (<50 nm) is reported in Lu3Al5O12:Ce3+ phosphor‐in‐silica‐glass (LuAG:Ce‐PiSG) despite being sintered at 1250 °C, endowing them with high internal quantum efficiency (>95%) and excellent stabilities. Combined experimental results and first‐principles calculations reveal that the large formation energy of SiAl point defects makes the undesired interfacial reaction between aluminate garnets and silica glass intrinsically suppressed. Phosphor‐converted LEDs/LDs fabricated by LuAG:Ce‐PiSG exhibit high luminous efficiency (195 lm W−1 @ 20 mA) and high brightness (1914 lm @ 13.4 W mm−2), approaching the performances of their ceramic counterparts. The results not only provide a way to balance the brightness and the price for SSL sources but also unleash the potential of silica glass as an inorganic matrix for emerging optical applications. [ABSTRACT FROM AUTHOR]

With the implementation of the Minamata Convention on Mercury, there is an urgent need to find a new way to generate ultraviolet‐C (UVC) light to replace mercury lamp. Upconversion phosphors have the potential to generate UVC light as they are able to convert low energy photons into high energy emissions. Here a new Sr2SiO4:Pr3+ phosphor is reported that could emit UVC light under excitation of a commonly used 450 nm laser diode, a cheap blue light‐emitting diode (LED) with central emitting wavelength at 450 nm, and even sunlight. Moreover, the potential applications of the UVC light of Sr2SiO4:Pr3+ phosphor upon excitation at 450 nm are demonstrated in several different situations, including static marking and dynamic tracking. Demonstration of the unique advantage of photon‐upconverted UVC emission of Sr2SiO4:Pr3+ in the application of sterilization is mainly focused, especially when the deep ultraviolet (DUV) LED cannot work adequately. This work opens a new route for generating UVC light and expands the applications of photon‐upconverted UVC emission, which is expected to be an indispensable supplement to the deep ultraviolet LED. [ABSTRACT FROM AUTHOR]

In recent years, inorganic lead halide perovskite quantum dots have been used in various optoelectronic fields for their excellent luminescence properties, such as narrow emission bands, ultra‐wide tunable emission wavelength, and high quantum efficiency. In this paper, different from luminescence optimization in most research, luminescence degradation of perovskite quantum dots is addressed by femtosecond laser irradiation and successfully used for three‐dimensional data storage in CsPbBr3 quantum dots doped glass. Photoluminescence (PL) degradation can be finely modulated by adjusting the laser parameters. PL degradation mechanism, investigated by optical spectroscopy and morphology characterization, is attributed to laser‐induced decomposition, recrystallization, and defection of CsPbBr3 quantum dots. Laser‐induced PL degradation and the followed PL recovery by heat treatment are repeated for several cycles, showing good reversibility. Multilayer PL degradation patterns are written into the glass and read out without crosstalk, indicating high‐reliability 3D optical storage characteristics. Amazingly, PL degradation can be induced by just a low‐energy single laser pulse with estimated subpicosecond writing time per bit, demonstrating its potential in high‐speed, low‐power consumption 3D optical storage. [ABSTRACT FROM AUTHOR]

The information burst in modern society poses new challenges to information preservation technology, both in storage efficiency, capacity, and security. Multi‐dimensional optical data storage based on the femtosecond laser direct writing technique is a promising way to face these challenges. Herein, a new optical storage method based on femtosecond laser‐induced local darkening of CdSe quantum dots doped glass is reported. Photoluminescence image and spectrum indicate that highly luminescent well‐crystallized CdSe quantum dots can be amorphized by a single femtosecond laser pulse and reconstructed by thermal treatment, resulting in reversible luminescence modulation, in which the luminous efficacy of CdSe quantum dots in glass matrix was well recovered after each cycle of writing and erasing. Complicated patterns written inside the glass and multi‐layer information are also successfully inscribed and well demonstrated. Data bit could be written by just one 380 fs single pulse with pulse energy as low as 100 nJ. The present work provides a potential way for three‐dimensional optical information storage and data encryption with low power consumption, fast writing speed, large capacity, and high security. [ABSTRACT FROM AUTHOR]

Broadband near‐infrared (NIR) phosphor‐converted light‐emitting diodes (pc‐LEDs) are recently regarded as the next‐generation smart light sources for miniaturized optical applications. However, their way to practical applications is largely obstructed by the lack of efficient NIR phosphors with photoluminescence (PL) spectrum covering the whole range of 700–1100 nm. Here, an ultra‐broadband NIR phosphor is designed by rationally constructing a Cr3+ → Yb3+ energy transfer system in a garnet crystal Lu2CaMg2Ge3O12 (LCMG). The disordering of the neighboring cations of LCMG is exploited for removing the inversion symmetry of octahedrally coordinated Cr3+ to promote its parity‐forbidden d–d transition probability; meanwhile, efficient Cr3+Yb3+ energy transfer is leveraged not only to enrich the short‐wave NIR PL in 950–1100 nm, but also to greatly improve the internal quantum efficiency (QE) (from 57.8% to 84.2%) as well as thermal stability. The resulting high external QE (35.6%) enables the demonstration of ultra‐broadband NIR pc‐LED with a record NIR output power of 93.2 mW (350 mA), which promises better performance of pc‐LEDs in non‐visible optical applications. This work provides a possible paradigm for developing ultra‐broadband NIR phosphors activated by transition metal ions. [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]