Search Results (1,294)

Chiral metasurfaces exhibit enormous potential in optical applications, and their integration with phase-change material vanadium dioxide (VO₂) provides a novel pathway for dynamic regulation. In this study, a chiral absorptive metasurface based on VO₂ is designed. By tuning the VO₂ conductivity around the operating frequency of 2.81 THz, the circular dichroism (CD) can be continuously adjusted from 0.06 to 0.95, realizing a high-contrast chiral switch. On this basis, the Pancharatnam–Berry (PB) phase is introduced to construct a chirality-dependent phase gradient: when the VO₂ conductivity is 200,000 S/m, only the left-handed circularly polarized (LCP) wave is subjected to periodic phase modulation, enabling controllable deflection of the reflected beam, while the right-handed circularly polarized (RCP) wave is selectively absorbed. This “chiral phase encoding” strategy simultaneously achieves absorptive CD tuning and reflective beam shaping on a single metasurface, significantly enhancing the flexible manipulation capability of circular polarization states in the terahertz band. It provides a compact and efficient solution for reconfigurable imaging, unidirectional communication, and integrated photonics systems. Full article

Seismic monitoring is a crucial step in ensuring the safety and resilience of building structures. The implementation of effective monitoring systems, particularly across large-scale, complex building clusters, is currently hindered by the limitations of traditional sensor placement methods, which suffer from low efficiency, high subjectivity, and difficulties in replication. This paper proposes an innovative AI-based Automated Layout Method for seismic monitoring devices, leveraging building geometric recognition to provide a scalable, quantifiable, and reproducible engineering solution. The core methodology achieves full automation and quantification by innovatively employing a dual-channel approach (images and vectors) to parse architectural floor plans. It first converts complex geometric features—including corner coordinates, effective angles, and concavity/convexity attributes—into quantifiable deployment scoring and density functions. The method implements a multi-objective balanced control system by introducing advanced engineering metrics such as key floor assurance, central area weighting, spatial dispersion, vertical continuity, and torsional restraint. This approach ensures the final sensor configuration is scientifically rigorous and highly representative of the structure’s critical dynamic responses. Validation on both simple and complex Reinforced Concrete (RC) frame structures consistently demonstrates that the system successfully achieves a rational sensor allocation under budget constraints. The placement strategy is physically informed, concentrating sensors at critical floors (base, top, and mid-level) and strategically utilizing external corner points to maximize the capture of torsional and shear responses. Compared with traditional methods, the proposed approach has distinct advantages in automation, quantification, and adaptability to complex geometries. It generates a reproducible installation manifest (including coordinates, sensor types, and angle classification) that directly meets engineering implementation needs. This work provides a new, efficient technical pathway for establishing a systematic and sustainable seismic risk monitoring platform. Full article

With the increasingly prominent issues of energy shortage and environmental pollution, the development of clean energy materials has become a core topic in the academic community. SnSe, as a material with moderate bandgap, a high light absorption coefficient, and environmental friendliness, has shown broad application prospects in the fields of photovoltaics and thermoelectrics. However, pure SnSe thin films have inherent defects, low carrier concentration, and high recombination rates, which limit their photoelectric conversion efficiency. This article provides a detailed overview of the characteristics of band engineering control technology, defect control technology, and carrier concentration control technology, as well as the improvements in the characteristics of SnSe thin films that they bring. This article systematically reviews the research progress on doping control technology for SnSe thin films characteristics in recent years and analyzes and discusses the differences in typical doping elements on SnSe thin films characteristics, such as optical bandgap and absorption coefficient, and applicable application scenarios, such as photovoltaics, near-infrared/infrared detection, and thermoelectric and flexible optoelectronic devices. Furthermore, the interaction between the doping mechanism of dopants and natural defects, as well as the influence of the structural parameters of doped films on doping efficiency, were analyzed, and a predictive design route for the doping mechanism of SnSe films was proposed. Finally, the influence of different atomic fractions on the characteristics of SnSe thin films was discussed. Low atomic fractions are beneficial for bandgap tuning and absorption enhancement; high atomic fractions can easily introduce phase separation and non-radiative recombination. It is suggested that future researchers can continue to focus on the precise control of atomic fractions, exploration of new element co-doping, and industrial large-scale production applications, providing theoretical guidance for the design and application of SnSe thin films in photothermal devices. Full article

To address poor wear resistance of surface metal grids for optical windows and low efficiency and poor uniformity of traditional embedded technologies, this study fabricates ultra-wear-resistant embedded metal grids on 180 mm × 180 mm × 8 mm sapphire via photolithography and large-area plasma etching. Etching grooves (depth about 300 nm) and depositing 135 nm silver (Ag) + 170 nm alumina (Al₂O₃) films, the grids exhibit transmittance 80.2%~80.9% (2~5 μm), wear resistance without damage, and reliable EMI shielding (Electromagnetic Interference Shielding) (3~18 GHz), offering a scalable solution for harsh-environment optoelectronic windows. The embedded structure integrates high transmittance, ultra-wear resistance, and reliable EMI shielding, addressing the core demands of optoelectronic windows in aerospace, outdoor monitoring, and other harsh environments where durability and stability are critical. The key innovation lies in the optimized integration of large-area plasma etching and low-temperature electron beam deposition, achieving precise control of groove depth uniformity (<4%) and transmittance uniformity (<1%) on high-hardness sapphire substrates, which overcomes the trade-off between efficiency and uniformity in traditional embedded technologies. Future applications include high-performance optical windows for airborne surveillance systems, space-borne optoelectronic devices, and harsh-environment industrial monitoring equipment, with potential extension to other high-hardness dielectric substrates. Full article

The memristor has long been known as a nonvolatile memory technology alternative and has recently been explored for neuromorphic computing, owing to its capability to mimic the synaptic plasticity of the human brain. The architecture of a memristor synapse device allows ultra-high-density integration by internetworking with crossbar arrays, which benefits large-scale training and learning using advanced machine-learning algorithms. In this review, we present a statistical analysis of neuromorphic computing device publications from 2018 to 2025, focusing on various memristive systems. Furthermore, we provide a device-level perspective on biomimetic properties in hardware neural networks such as short-term plasticity (STP), long-term plasticity (LTP), spike timing-dependent plasticity (STDP), and spike rate-dependent plasticity (SRDP). Herein, we highlight the utilization of optoelectronic synapses based on 2D materials driven by a sequence of optical stimuli to mimic the plasticity of the human brain, further broadening the scope of memristor controllability by optical stimulation. We also highlight practical applications ranging from MNIST dataset recognition to hardware-based pattern recognition and explore future directions for memristor synapses in healthcare, including artificial cognitive retinal implants, vital organ interfaces, artificial vision systems, and physiological signal anomaly detection. Full article

Piezochromic nanomaterials, whose optical responses can be reversibly tuned by mechanical stimuli, have recently gained prominence as versatile platforms for strain-programmable light–matter interactions. Their mechanically responsive band structures, excitonic states, and defect energetics have enabled a wide range of optoelectronic demonstrations—including pressure-tunable emitters, reconfigurable photonic structures, and adaptive modulators—which collectively highlight the unique advantages of mechanical degrees of freedom for controlling optical functionality. These advances naturally suggest new opportunities in photovoltaic technologies, where experimentally validated phase stabilization and defect reorganization under low-strain thin-film conditions could address long-standing limitations in solar absorbers and device stability. Meanwhile, stress-mediated bandgap tuning—largely inferred from high-pressure laboratory studies—presents a conceptual blueprint for future adaptive spectral response and structural self-monitoring. However, the application of these mechanisms faces a major challenge in bridging the magnitude gap between GPa-level high-pressure phenomena and the low-strain regimes of realistic operational environments. Future development requires advances in low-threshold responsive materials, innovative strain-amplifying device architectures, and the pursuit of intelligent, multi-functional system integration. Full article

With the development of space laser networks, miniaturization and lightweight design have become inevitable trends in laser terminal development. In laser links, functions such as spot position measurement, ranging, and data transmission are usually performed by multiple independent units. Integrating these three functions can effectively reduce the size of the opto-mechanical structure and save space within the optical transceiver, thereby supporting the lightweight and compact growth of laser terminals. This paper presents an integrated scheme based on an optical direct-sequence spread-spectrum (DSSS) quadrant detector (QD) and regenerative codes, which enables spot position measurement, ranging, and data transmission through an optical transceiver. The core of this approach involves using a code tracking loop to perform correlation gain calculation, phase comparison, and demodulation of the pseudo-noise code-modulated laser signal, thereby achieving all three functions simultaneously. A desktop experimental system was built to test and verify the scheme’s accuracy and precision. The system achieved a ranging accuracy of 14 mm (1σ), a spot position measurement accuracy of 0.83 μm (1σ) at the target center, and a communication sensitivity of −31 dBm at a 10⁻⁴ bit error rate (BER) with a data rate of 1 Kbps. This study provides a reference for future lightweight optical terminals. Full article

Lead-free transparent ferroelectric ceramics with integrated opto-electro-mechanical functionalities are pivotal for next-generation multifunctional devices. In this study, K_0.48Na_0.52NbO₃-xLa₂O₃ (KNN-xLa, x = 0.005 − 0.04) ceramics were fabricated via a conventional solid-state route to investigate the La³⁺-induced multiscale structural evolution and its modulation of optical and electrical properties. La³⁺ substitution drives a critical structural transition from an anisotropic orthorhombic phase (Amm2) to a high-symmetry pseudocubic-like tetragonal phase (P4mm) for x ≥ 0.025, characterized by minimal lattice distortion (c/a = 1.0052). This enhanced structural isotropy, coupled with submicron grain refinement (<1 μm) driven by ${\mathrm{V}}_{\mathrm{A}}^{\prime }$-mediated solute drag, effectively suppresses light scattering. Consequently, a high-transparency plateau (T₇₈₀ ≈ 53–58%, T₁₇₀₀ ≈ 70–72%) is achieved for 0.025 ≤ x ≤ 0.035. Simultaneously, the system undergoes a crossover from normal ferroelectric (FE) to relaxor (RF) state, governed by an FE–RF boundary at x = 0.015. While x = 0.005 exhibits robust piezoelectricity (d₃₃ ≈ 92 pC/N), the x = 0.015 composition facilitates a transitional polar state with large strain (0.179%) and high polarization (P_m ≈ 33.3 μC/cm², P_r ≈ 15.8 μC/cm²). Piezoresponse force microscopy (PFM) confirms the domain evolution from lamellar macro-domains to speckle-like polar nanoregions (PNRs), elucidating the intrinsic trade-off between optical transparency and piezoelectricity. This work underscores La³⁺ as a potent structural modifier for tailoring phase boundaries and defect chemistry, providing a cost-effective framework for developing high-performance transparent electromechanical materials. Full article

We propose a strain-optimized design strategy for lattice-matched InAs_1−xSb_x/Al_1−yIn_ySb Type-I quantum wells (QWs) that emit across the near-to mid-infrared spectrum (2–5 µm). By combining elastic strain energy minimization with band offset calculations, we identify Type-I alignment for Sb contents (x ≤ 0.40) and In contents (0.10 < y ≤ 1). At the same time, Type-II dominates at higher Sb compositions (x ≥ 0.50). Using the transfer matrix method under the effective mass approximation, we demonstrate precise emission tuning via QW thickness (L_W) and compositional control, achieving a wavelength coverage of 2–5 µm with <5% strain-induced energy deviation. Our results provide a roadmap for high-efficiency infrared optoelectronic devices, addressing applications in sensing and communications technologies. Full article

To meet the requirements of non-mechanical beam scanning and acquisition in space laser communication, this study proposes a two-dimensional scanning and acquisition method based on a silicon-based optical phased array (OPA). The OPA utilizes thermo-optic phase modulation to achieve horizontal beam pointing, while vertical beam pointing is controlled by wavelength tuning. By combining the OPA with a rectangular spiral scanning strategy, non-mechanical scanning is realized and beam acquisition experiments are carried out. Experimental results demonstrate that for an 8° step signal, the horizontal and vertical rise times are 156.8 μs and 214.76 ms, respectively. A full scan of 440 points covering a ±4° field of view is completed in 8.119 s. Acquisition experiments were conducted assuming a Gaussian-distributed uncertainty region (standard deviation $\sigma =1°$). Out of 106 independent trials, a success rate of 97.17% was achieved with an average acquisition time of 0.41 s. This work experimentally applies a rectangular spiral scanning strategy to an OPA-based acquisition system, addressing a capability that has been largely missing in previous studies. These results verify that the OPA technology has good scanning efficiency and acquisition robustness in space laser communication applications. Full article

We experimentally and theoretically demonstrate coexistence of three different wavelength-multiplexed bound dual-frequency pulses in an all-fiber mode-locked fiber laser, effectively achieved by exploiting polarization-dependent loss effects and two uneven gain peaks of Er-doped fiber. With the single wall carbon-nanotube-based intensity modulation, wavelength-multiplexed dual-frequency pulses located at 1531.1 nm and 1556.6 nm are obtained. Changing the polarization rotation angles in the fiber cavity, one of the two asynchronous pulses evolves into a bound state of a doublet, in which the center wavelength of the bound solitons is centered at ~1530 nm or ~1556 nm. The relative phase between the two bound solitons or modulation depth of bound solitons can be switched by a polarization controller. A simulation method based on coupled Ginzburg–Landau equations is provided to characterize the laser physics and understand the mechanism behind the dynamics of tuning between different bound dual-frequency pulses. The proposed fiber laser will provide a potential way to understand multiple soliton dynamics and implementation in optical frequency combs generation. Full article

The detection of trace nitrogen dioxide (NO₂) is critical for environmental monitoring and industrial safety. Among various sensing technologies, chemiresistive sensors based on semiconducting metal oxides are prominent due to their high sensitivity and fast response. However, their application is hindered by inherent limitations, including low selectivity and elevated operating temperatures, which increase power consumption. Two-dimensional metal oxysulfides have recently attracted attention as room-temperature sensing materials due to their unique electronic properties and fully reversible sensing performance. Meanwhile, their combination with optoelectronic gas sensing has emerged as a promising solution, combining higher efficiency with minimal energy requirements. In this work, we introduce non-layered 2D indium oxysulfide (In₂S_xO_3−x) synthesized via a two-step process: liquid metal printing of indium followed by thermal annealing of the resulting In₂O₃ in a H₂S atmosphere at 300 °C. The synthesized material is characterized by a micrometer-scale lateral dimension with 6.3 nm thickness and remaining n-type semiconducting behavior with a bandgap of 2.53 eV. It demonstrates a significant response factor of 1.2 toward 10 ppm NO₂ under blue light illumination at room temperature. The sensor exhibits a linear response across a low concentration range of 0.1 to 10 ppm, alongside greatly improved reversibility, selectivity, and sensitivity. This study successfully optimizes the application of 2D metal oxysulfide and presents its potential for the development of energy-efficient NO₂ sensing systems. Full article

Low work function (LWF) materials are essential for enabling efficient systems’ behavior in applications ranging from vacuum electronics to energy conversion devices and next-generation opto-electronic interfaces. Recent advances in theory, characterization, and materials engineering have dramatically expanded the candidates for LWF systems, including alkali-based compounds, perovskites, borides, nitrides, barium and scandium oxides, 2D materials, MXenes, functional polymers, carbon materials, and hybrid architectures. This review provides a comprehensive overview of the fundamental mechanisms governing the work function (WF) and discusses the state-of-the-art measurement techniques, as well as the most used computational approaches for predicting and validating WF values. The recent breakthroughs in engineering LWF surfaces through different methods are discussed. Special emphasis is placed on the relationship between predicted and experimentally measured WF values, highlighting the role of surface contamination, reconstruction, and environmental stability. Performance, advantages, and limitations of major LWF material families are fully analyzed, identifying emerging opportunities for next applications. Finally, current and fundamental challenges in achieving scalable, stable, and reproducible LWF surfaces are considered, presenting promising research directions such as high-throughput computational discovery and in situ surface engineering with protective coatings. This review aims to provide a unified framework for understanding, achieving, and advancing LWF materials toward practical and industrially relevant technologies. Full article

High-power-density LED devices have emerged as a prominent focus in current research and industrial development, largely due to their role in advancing LED lighting technologies. At high power and high current, the structure and area of the thermoelectrically separated copper substrate connected to the LEDs significantly influence the device’s optoelectronic performance, yet detailed studies in this area remain limited. To address this issue, blue and white LED devices with a maximum power rating of 400 W were fabricated and soldered onto copper substrates with diameters of 20 mm, 25 mm, and 32 mm. The influence of substrate area on the I–V and I–L characteristics of the LEDs was systematically measured and analyzed at different operating temperatures. Additionally, variations in operating voltage and luminous intensity with temperature were investigated under specific driving currents. Infrared thermal imaging was employed to examine the thermal field distribution under varying substrate sizes and current levels. The results show that increasing the copper substrate diameter from 20 mm to 25 mm and further to 32 mm leads to a significant improvement in LED optoelectronic performance. To determine the diameter threshold beyond which performance gains diminish, a 3D COMSOL 6.1. model was developed. The model reveals that expanding the diameter from 32 mm to 35 mm results in only a marginal improvement, while further increasing it to 40 mm offers a negligible additional benefit, thereby identifying the optimal substrate area for performance saturation. Full article

High-sensitivity microwave sensing plays a vital role in material characterization and nondestructive testing, with its performance being largely determined by the quality factor (Q factor) of the sensing structure. In this work, a high-Q microwave metasurface sensor based on the mechanism of bound states in the continuum (BIC) is designed and realized to overcome the intrinsic Q-factor limitations of conventional microwave resonators. By introducing a controlled asymmetric perturbation into the meta-atom, a quasi-BIC mode is successfully excited, and its sensing performance is systematically investigated through frequency-domain simulations. The results indicate that the proposed metasurface achieves an exceptionally high radiation Q factor of up to 4599.7 in the microwave band, along with a refractive index sensitivity of 31.267 GHz/RIU. These findings not only demonstrate the significant potential of the BIC mechanism for achieving ultra-high-Q microwave resonators but also provide an effective and promising approach for the development of high-performance microwave sensing systems. Full article