Topological lasers have emerged as a promising platform for robust photonic systems, yet current implementations relying on semiconductor microcavities and resonators suffer from fundamental constraints including low optical gain, limited output power and fixed lasing sites. To address these challenges, we present an all-solid-state, reconfigurable topological laser based on a Su-Schrieffer-Heeger waveguide array platform, fabricated in disordered laser crystal (Nd:BaLaGa3O7). Harnessing the high gain provided by solid-state lasers, we experimentally and theoretically demonstrate single-mode, continuous-wave topological lasing with output power surpassing 100 mW. In addition to conventional topological edge lasing, we observe topological lasing at trivial lattice terminations and reconfigurable interface sites at arbitrary lattice positions. This unconventional behavior arises from the non-Hermitian parity-time symmetry transition in subsystem at elevated pump power. Our work demonstrates on-demand, site-selectable topological lasing, offering both fundamental insights into topological phase transitions in non-Hermitian systems and practical opportunities to develop robust, reconfigurable topological photonic devices for advanced lasing and optical information processing. Topological lasers usually emit light from a fixed spot. Here, authors report on an all-solid-state platform where topological lasing is demonstrated at trivial lattice terminations as well as at reconfigurable arbitrary sites. The device consists of a Su-Schrieffer-Heeger waveguide array, printed in a disordered Nd:BaLaGa₃O₇ crystal.

HfO2-based ferroelectrics hold exceptional promise for next-generation microelectronics, offering robust ferroelectricity down to the nanoscale while maintaining compatibility with CMOS technology. However, stabilization of the ferroelectric orthorhombic phase (o-FE) is consistently challenged by the simultaneous formation of its antiferroelectric counterpart (o-AFE). This unresolved o-FE/o-AFE competition, particularly under strain, is a critical factor driving undesirable device phenomena like 'wake-up' and 'fatigue'. To decipher the strain-confinement effects governing o-FE stability at coherent o-phase interfaces, we have developed a bulk-crystal strategy. This approach overcomes thin-film strain complexities by leveraging larger grain sizes and simplified strain landscapes. Integrating advanced microscopy with theoretical calculations, we demonstrate that specific anisotropic-biaxial strain-tensile along the a-axis coupled with compressive along the b-axis-proves sufficient to stabilize the o-FE phase, while strain relaxation favors o-AFE dominance. Direct atomistic tracking reveals the mechanisms underlying the formation of the o-FE phase and the evolution pathway between o-FE and o-AFE phases. Our work establishes a unified strain-mediated mechanism for the ubiquitous phase switching between the o-FE and o-AFE phases observed in HfO2-based materials, delivering a fundamental framework to design high-performance fluorite ferroelectrics. This has broad implications for advancing microelectronics and neuromorphic computing.

With the rapid progression of photoelectrical technology, the development of multi-mode photodetectors is highly desirable for complex application scenarios. Here, we fabricate 1T-2H mixed-phase MoS2 films via electrochemical intercalation technique, which intrinsically integrates a 2H-phase photosensitive network with a 1T-phase dispersed capacitance. By modulating the external bias and phase distribution, a family of photodetectors with tailored tri-mode operation was achieved among reconfigured photocapacitive (PCC), photovoltaic (PV), photoconductive (PC) modes. Breaking the conventional perception of capacitors as parasitic components in optoelectronic devices, our work harnessed the capacitive effect as an effective signal source, enabling self-powered operation and high-sensitivity detection. It exhibits efficient charging pulses and superior self-resetting characteristics with a response speed reaching 19.2 ms and an average charge-discharge efficiency of 87.6%. From device design to application prototype, our proof-of-concept demonstrations in non-contact sensing, flame monitoring, and image reconstruction highlight the positive potential in intelligent sensing technologies. This study not only provides a novel design paradigm for phase engineering in multi-functional photodetection, but also its successful implementations hold significant promising for advancing intelligent optoelectronics, such as optoelectronic chips and biosensing.

Sesquioxide ceramics are promising candidates for high-power laser applications, yet achieving high optical quality remains challenging. This is primarily due to rapid grain-boundary mobility during the final stage of sintering and pump-induced photodarkening under high-power excitation, particularly when traditional tetravalent sintering additives (e.g., ZrO2) are used. Here, approximately 1 : 1 (molar) Zr4+-Ca2+ codoping is introduced to regulate the sintering behaviors of Yb:Y2O3 ceramics, yielding dense microstructures with uniform elemental distributions. The charge compensation enabled by Zr-Ca codoping suppresses the formation of point defects, thereby significantly mitigating photodarkening. As a result, the optimized 0.02 at% Zr-Ca codoped sample delivers a maximum continuous-wave (CW) output power of 20.5 W at 1076 nm with a slope efficiency of 65.4%. These results demonstrate that Zr-Ca codoping is an effective strategy for fabricating high-performance sesquioxide laser ceramics with improved optical quality and enhanced resistance to pump-induced photodarkening.

In this Letter, a high-repetition nanosecond vacuum ultraviolet (VUV) laser at 177.3 nm was presented by direct frequency-doubling technology in period-disorder SiO2 (PDSO) crystals. PDSO devices have periodic amorphous regions with a few micrometers scale, comparable to the coherent length of frequency-doubling, thus compensating for the momentum mismatch in second-harmonic generation. The number of amorphous periods was optimized to minimize interfacial optical loss and improve the overall conversion efficiency by four orders of magnitude, compared to quartz crystal. As a result, the nanosecond VUV laser at a high repetition rate over 50 kHz was realized, yielding an average output power of 1.75 mW and a peak power of 3.68 W. This work presents the first demonstration of a high-repetition nanosecond VUV laser (exceeding 10 kHz) among all nonlinear crystals, achieving a 10-fold improvement in repetition rate over previous crystals.

Complementary-metal-oxide-semiconductor-compatible HfO2-based high-κ dielectrics are pivotal for next-generation electronics in the post-Moore’s Law era. However, establishing coherent interfaces via morphotropic phase boundaries across the tetragonal and orthorhombic (ferroelectric or antiferroelectric) phases—a key strategy for enhancing dielectric properties—remains challenging due to unclear atomic-scale mechanisms and inherent thermal instability, which compromises long-term stability and reliability. To address this, we leverage metallurgical quenching principles to stabilize tetragonal/orthorhombic-antiferroelectric morphotropic phase boundaries in HfO2-based (Lu:Hf0.6Zr0.4O2) bulk crystals. Through precise composition tuning and growth optimization, we stabilize these metastable morphotropic phase boundaries at the tetragonal/orthorhombic-antiferroelectric interface at room temperature, achieving a comparable κ-value (57) to actively studied tetragonal/orthorhombic-ferroelectric counterparts. Microstructural characterization reveals how tensile strain within the t-phase drives dielectric enhancement through softening of the low-frequency Eu phonon mode. Critically, the tetragonal/orthorhombic-antiferroelectric morphotropic phase boundary demonstrates a 58

Short-wave ultraviolet (200-280 nm) crystals with large birefringence are important but scarce for polarization state modulation. The optical anisotropy in crystals is significantly influenced by the spatial arrangement of microscopic functional units. Herein, a design concept of constructing two-dimensional and linear arrangement structures is proposed to achieve large birefringence. By employing a symmetry-breaking strategy, commonly used triangular π-conjugated groups were extended to [NO2]-, [COOH]-, methylguanidine [C2N3H8]+, and guanylurea [C2N4H7O]+ groups with large anisotropic polarization. Driven by hydrogen bonding, two crystals, [C2N3H8]NO2 and [C2N4H7O]COOH, with ideal linear ordering were synthesized with the birefringence markedly enhanced to 0.331 and 0.413@546 nm, respectively. In particular, the [C2N4H7O]COOH crystal achieves a rare balance between a wide bandgap and superior birefringence in the short-wave ultraviolet region. Moreover, centimeter-sized single crystals were successfully obtained. This work not only provides new ideas for designing birefringent crystals but also offers promising candidate materials for optical modulation.

Plasmons with nearly dispersionless, long-lived behavior in momentum space have great potential for novel imaging techniques and nonlinear optics, due to their ability to generate localized plasmon wave packets and to enhance giant light fields in real space. However, flat plasmons typically manifest in low-dimensional systems that conventionally originate from intraband free electrons and are usually confined to restricted momentum regions (q < ∼0.7 Å-1), which limits their applications. Here, we report the emergence and polymorphic phase-engineering of flat plasmons in the strongly correlated oxide Ti2O3, characterized by highly anisotropic and long-lived behavior (q > 0.7 Å-1). The electronic correlation effect, that is, the on-site Coulomb interaction (U), was tuned by polymorphism through epitaxial stabilization. We demonstrate a close relationship between U and the energy fluctuation of plasmons (Δωp). Specifically, a larger U leads to smaller Δωp, that is, a stronger electronic correlation effect makes plasmons flatter. This tunability can be attributed to the renormalized bandwidth of Hubbard bands, which contribute to the generation of those flat plasmons. Our work offers a practical strategy for manipulating flat plasmons in strongly correlated systems, thereby promoting the development of novel plasmonic and nonlinear optical devices.

Yellow light sources, emitting at the wavelength of 570 to similar to 590 nm, are indispensable for many applications in biological diagnosis and treatment. However, a compact yellow laser is very difficult to attain owing to the absence of efficient electronic transitions, referring to the long-standing "yellow gap" over 60 years in the solid-state laser field. Here, we proposed a phonon engineering strategy to create yellow lasers in Nd3+-doped garnet laser crystals, which combines thermally driven electron-phonon coupling and intracavity frequency-doubling simultaneously. Via an ingenious cavity design, continuous-wave yellow lasing at 575.5 to 583 nm is realized from Nd:YAG and Nd:GGG by coupling various phonon modes. Benefiting from the thermally enhanced lattice vibrations, these yellow lasers exhibit an anomalous temperature dependence with improved output powers at high temperatures. Moreover, using this high-photon-flux yellow laser as a pump source, the fluorescent intensity of the Alexa Fluor probe is boosted by 100 times compared with the traditional green laser excitation, indicating its great potential for flow cytometry applications. These findings not only open up the possibility of creating unprecedented laser emissions in the traditional crystals but also provide a light source for molecular labeling and biological detection.

Lithium-oxygen batteries (LOBs) represent a promising next-generation energy storage technology due to their ultrahigh theoretical energy density. However, their practical application is hindered by critical challenges including electrolyte volatility and decomposition, lithium anode degradation, and the incomplete reversibility of Li2O2 discharge products. Herein, we design a novel fluorinated ether co-solvent, 1,1'-[oxybis[(1,1,2,2-tetrafluoro-2,1-ethanediyl)-oxy(2,2-difluoro-2,1-etha-nediyl)]]bis(1,1,1-trifluoromethanesulfonate) (FTE), which features a high boiling point that effectively suppresses electrolyte evaporation. More importantly, its incorporation promotes the formation of a fluorine-rich solid electrolyte interphase (SEI) on the lithium metal anode, significantly enhancing interfacial stability. Simultaneously, FTE modulates the Li+ solvation structure, steering the growth of Li2O2 away from the conventional toroidal morphology toward a highly decomposable three-dimensional porous network. These synergistic effects collectively contribute to a substantial improved cycling performance, enabling LOBs with FTE-modified tetraethylene glycol dimethyl ether based (FTE/TEG-based) electrolyte to deliver high discharge specific capacities, excellent rate capabilities, and remarkable cycling stability. This study highlights a multifunctional electrolyte design strategy that prioritizes long-term reversibility, paving the way for practical high-energy-density LOBs.

Chemical substitution is an effective strategy to enhance the desired performances of materials based on known structural prototypes. However, it almost invariably introduces intrinsic defects, such as vacancies and twinning defects, which couple with dopants and obscure or degrade the intrinsic properties. Therefore, chemical substitution that enables atomically precise engineering of materials without generating defect structures remains challenging. Here, we propose a quasi-degenerate cation occupation strategy to overcome this detrimental coupling and successfully apply it to the langasite-family nonlinear optical (NLO) crystal, La 3 TiGa 5 O 14 (LGTi). Therein, the cross-site occupation of Ti and Ti 3+ /Ti 4+ redox flexibility improve the kinetic accessibility of oxygen-vacancy ( V O ) defects associated with cation disorder, enabling their removal during oxidative annealing. The oxidized LGTi single crystal has a V O -related defect concentration below the electron paramagnetic resonance detection limit and exhibits an enhanced NLO performance, including a strong laser damage threshold of 2.53 GW/cm 2 and a large NLO coefficient of 3.51 pm/V, which are the best values ever reported for langasite-family crystals. Overall, this work provides a quasi-degenerate cation occupation strategy to mitigate substitution-induced defects in structurally complex crystalline systems and has great prospects in enhancing material performance.

Lithium-oxygen batteries hold great promise for next-generation energy storage systems due to their ultrahigh theoretical energy density. However, their development is hindered by high charging overpotentials and poor cycle stability. Herein, we propose a strategy of electronic structure regulation to design a Ru-modified Pt/C catalyst to address the key challenge of tuning the charge overpotential. Electron delocalization occurs from Ru to Pt in RuPt because of the electronegativity difference between Ru and Pt. The calculation results show that the 4d(Ru)-5d(Pt) orbital coupling regulates the d-band distribution of Pt sites in RuPt, including the moderate downshift of d-band center systematically across the Pt's five d-suborbitals and the broadening of d-band above the Fermi energy level. It weakens the adsorption strength towards oxygen-containing species and smooths the energy barriers of stepwise reactions during OER. Experimental results demonstrate that the Ru-Pt/C catalyst significantly reduces the overpotential by ∼1 V compared to Pt/C. Meanwhile, the Li-air battery also presents a low overpotential of 0.75 V after 100 cycles. This work advances the fundamental understanding of d-band regulation via engineering electronic structure in oxygen electrocatalysis and provides a practical pathway to mitigate overpotential-related challenges in high-energy-density metal-air batteries.

Continuous-wave vacuum-ultraviolet (VUV) radiation near 190-200 nm is highly desirable for high-resolution photoemission spectroscopy, precision spectroscopy, and semiconductor metrology, yet compact all-solid-state sources in this spectral region remain challenging due to the limited nonlinear materials and complex cascaded conversion schemes. Here, we propose a straightforward approach for achieving a VUV laser in the continuous-wave regime with only two-step nonlinear conversion processes. As a proof-of-principle study, we choose a visible Pr:YLF laser platform: the 522-nm (3P1→3H5) laser is at first intracavity frequency-doubled to 261 nm and subsequently sum-frequency mixed with the 721 nm (3P0→3F4) transition in β-BaB2O4 (BBO), delivering milliwatt-level continuous-wave lasers at 192 nm. The proposed approach with two-step nonlinear-frequency up-conversions offers a markedly simplified path for compact, scalable continuous-wave VUV laser sources across the 190-200 nm spectral region.

Lithium niobate (LiNbO3) crystals and devices have many important applications in laser frequency doubling and electro-optic frequency comb generation. Especially for Nd3+-doped LiNbO3, holding optical gain, electro-optic modulation, and frequency conversion concurrently, serves as the promising platform for on-chip integrated optical applications. However, despite of the first discovery over fifty years, the fundamental transition selection rules of Nd-doped LiNbO3 crystal still remain elusive due to the complex Stark levels and undefined local symmetry. In this work, we present a comprehensive characterization of Nd:MgO:LiNbO3 crystals, including crystal growth, optical spectrum, and transition selection rules. Based on the absorption spectrum and polarized fluorescence emission, we clarify the Stark splitting levels in Nd:MgO:LiNbO3 crystal and give a panorama for 4F3/2→4I9/2, 4I11/2, 4I13/2 transitions. Meanwhile, we first employed the Γ4, Γ5, and Γ6 irreducible representation to calibrate the Stark levels of Nd3+ ions, which can establish a theoretical foundation for laser with different polarization characteristics in LiNbO3. Moreover, we performed the polarized laser generation at 1.08, 1.09, 1.38, and 1.4 μm to check the validity of fine energy level diagram and the electric-dipole selection rules by light polarization. To the best of our knowledge, this is the first report on laser oscillation at 1.4 μm in Nd:MgO:LiNbO3 crystals.

Lithium-oxygen (Li-O2) battery is favored among “beyond lithium-ion” technologies for sustainability because of its exceptional energy density. Major impediments are the poor cycle stability and grievous capacity degradation at high current densities. We address these issues by a “killing two birds with one stone” O2-pressure protocol. It first resolves efficient O2 mass transport at high rates.æ The accelerated reaction kinetics optimizes the composition and growth pathway of discharge products. This protocol secondly achieves protection of Li anodes via densifying corrosion layers on them. Consequently, the battery delivers both ultrahigh discharge capacity (> 9,000 mAh g−1) at 3,000 mA g−1 and excellent cycling stability. Under a dual-strategy effect of high-pressure O2 and artificial protection layers, the battery actualizes over 11-fold increase in cycle life of 5,170 h (2,585 cycles). The strategy opens avenues for advancing Li-O2 batteries towards practical application and confers the extension to other gas-based batteries.

In this Letter, a direct-diode-pumped monolithic yellow laser at 589 nm was realized in the Yb³⁺-doped YCa₄O(BO₃)₃ (Yb:YCOB) crystal. This intriguing yellow light emission originates from the collaborative phonon-coupling and self-frequency doubling effect, which enables a simple laser setup and excellent power scaling capacity. Via an effective direct-cooling scheme, the thermal accumulation on the Yb:YCOB gain medium was alleviated, thus yielding high-power laser loading and stable conversion efficiency. As a result, the continuous-wave laser power at 589 nm was improved to 10.2 W with a high optical-to-optical conversion efficiency of 24.3%. This work presents the first, to the best of our knowledge, ten-watt-level microchip yellow laser, in which the output power is ten times higher than that of diode-pumped Dy 3+ - and Tb 3+ -doped lasers.