Reconfigurable Intelligent Surface (RIS) technologies have been considered as a promising enabler for 6G, enabling advantageous control of electromagnetic (EM) propagation. RIS can be categorized into multiple types based on their reflective/transmissive modes and polarization control capabilities, all of which are expected to be widely deployed in practical environments. A reliable RIS channel model is essential for the design and development of RIS communication systems. While deterministic modeling approaches such as ray-tracing (RT) offer significant benefits, a unified model that accommodates all RIS types is still lacking. This paper addresses this gap by developing a high-precision deterministic channel model based on RT, supporting multiple RIS types: reflective, transmissive, hybrid, and three polarization operation modes. To achieve this, a unified EM response model for the aforementioned RIS types is developed. The reflection and transmission coefficients of RIS elements are derived using a tensor-based equivalent impedance approach, followed by calculating the scattered fields of the RIS to establish an EM response model. The performance of different RIS types is compared through simulations in typical scenarios. During this process, passive and lossless constraints on the reflection and transmission coefficients are incorporated to ensure fairness in the performance evaluation. Simulation results validate the framework's accuracy in characterizing the RIS channel, and specific cases tailored for dual-polarization independent control and polarization rotating RISs are highlighted as insights for their future deployment. This work can be helpful for the evaluation and optimization of RIS-enabled wireless communication systems.

Objective Chiral metasurfaces capable of discriminating between left-and right-handed circularly polarized light (LCP and RCP) are of great significance for polarization optics, enantio-sensitive detection, and integrated photonic devices. However, the optical activity of natural chiral materials is intrinsically weak, and most artificial chiral metasurfaces require complicated three-dimensional architectures or multilayer stacking, which increase fabrication difficulty and limit scalability. To address these challenges, this work introduces an origami-inspired nanohole array metasurface that enhances circular dichroism (CD) through a simple folding transformation. The objective of this study is to demonstrate a compact, low-cost, and tunable chiral platform that achieves strong CD and provides new physical insights into geometry-induced chirality. Methods The proposed metasurface is constructed from a gold film perforated with a periodic array of bar-shaped nanoholes. In its planar state, the structure preserves mirror symmetry and thus exhibits negligible CD. By introducing a single folding step along the unit-cell axis, mirror symmetry is broken, creating a quasi-three-dimensional geometry. The optical response is numerically investigated using the finite-difference time-domain (FDTD) method. Transmission spectra under left-and right-circularly polarized light are simulated for both unfolded and folded configurations. The CD spectra are obtained by calculating the difference in transmission between LCP and RCP components. A series of parameter studies is conducted to assess the influence of folding angle, film thickness, and aperture geometry on the CD response. Specifically, the folding angle beta is varied from-80 degrees to +80 degrees, the gold film thickness is adjusted between 10 and 40 nm, and the aperture length and width are tuned to evaluate their impact on coupling efficiency. In addition, a theoretical framework based on Jones matrix formalism is established. The full transmission matrix is reconstructed from co-polarized and cross-polarized transmission amplitudes and converted into the circular basis, yielding theoretical CD spectra that are directly compared with FDTD simulations. Results and Discussions Numerical simulations demonstrate that the folded metasurface exhibits a dramatic enhancement of optical chirality compared with the planar case. The CD spectrum of the folded structure reaches a maximum value of 0.58 at 621 nm and shows an opposite-sign resonance at 739 nm, corresponding to dual-wavelength selective absorption. This dual-band feature indicates strong discrimination between circular polarizations, providing additional degrees of freedom for optical functionality. The folding angle beta plays a decisive role in determining the magnitude of chirality. CD increases steadily with beta, with optimal performance observed near 45 degrees , where structural asymmetry is maximized. Variations in the inclination angle alpha further confirm that geometric perturbations of the nanohole orientation strongly influence polarization-dependent responses. Film thickness also exerts significant influence. At 20 nm, the metasurface exhibits the strongest CD, while increasing thickness to 40 nm reduces the CD value due to enhanced multiple scattering and reflection. This trend is further illustrated by electric-field distribution maps, which reveal weaker near-field localization at larger thicknesses. Aperture geometry contributes an additional tuning mechanism. Changes in the hole length a have only minor effects, whereas widening the hole significantly alters the magnitude and spectral position of the CD peaks, highlighting the sensitivity of coupling efficiency to lateral dimensions. The Jones matrix analysis provides clear physical insight into the enhancement mechanism. The amplitudes of the four matrix elements reveal large off-diagonal terms, signifying strong cross-polarization conversion. The phase differences between matrix components reveal pronounced phase mismatches that amplify polarization-dependent interference. As a result, the theoretical CD spectrum reconstructed from the matrix exhibits peaks and troughs closely aligned with those obtained by simulation, validating the model. These results confirm that the observed chirality enhancement originates from the interplay of strong cross-polarization coupling and phase delay between orthogonal modes. To further benchmark the proposed design, we summarize representative chiral metasurfaces reported in recent years, including planar asymmetric patterns, twisted bilayers, all-dielectric structures, and toroidal-mode metasurfaces. Compared with these approaches, the origami nanohole array achieves one of the highest CD values (0.58) while maintaining structural simplicity and requiring only a single folding operation. Importantly, the structure exhibits dual-wavelength selectivity and geometrical tunability via folding angle adjustment, which are not simultaneously available in most previously reported devices. Conclusions This study demonstrates that an origami-inspired nanohole metasurface can achieve strong and tunable chiral responses with simplified fabrication. A maximum CD of 0.58 at 621 nm and an opposite resonance at 739 nm confirm its dual-wavelength selective capability. Systematic parameter analysis highlights the roles of folding angle, film thickness, and aperture geometry in tailoring the spectral response. Theoretical predictions based on Jones matrix formalism are consistent with numerical simulations, confirming that enhanced cross-polarization coupling and phase mismatch drive the CD amplification. Beyond theoretical validation, the design offers distinct practical advantages over traditional chiral metasurfaces. Its single-step folding operation reduces fabrication complexity and cost, making it more compatible with large-area processing. Nevertheless, challenges such as maintaining folding-angle precision, ensuring large-area uniformity, and guaranteeing structural stability must be addressed before practical implementation. Future research may explore multi-fold or multilayer origami configurations and employ advanced nanofabrication strategies to further enhance performance. Overall, the origami metasurface provides a promising and effective pathway toward low-cost, reconfigurable, and high-performance chiral devices for applications in chiral sensing, polarization control, and integrated photonics.

The reflectance-mode photoplethysmography (PPG) technique provides an encouraging platform for heart rate and respiration rate precise monitoring, due to its advantages of the restriction of placed area. The demand for respiration and heart rate monitoring on the reflectance-mode PPG is lowing baseline drift for accuracy low-frequency PPG signal detecting from the photodetector. In this study, a surface cleaning-passivation strategy (SCPS) is developed to simultaneously remove residual solution and suppress the defect on the surface of MAPbBr3 perovskite single crystals, dramatically reducing trap densities and thus resulting in a high-quality surface. Photodetector based on the SCPS-MAPbBr3 single crystal exhibits a reduced dark current of 2.376 nA at bias of 10 V and a reduced dark current drift from 1.36 x 10-5 to 6.07 x 10-7 nAmmV-1s-1 at 200 Vcm-1. A reflectance-mode PPG monitoring system is built based on the excellent MAPbBr3 perovskite single crystal photodetector, which is capable to lower baseline drift of PPG waveforms, enabling the accurate low-frequency signals extraction. This work offers a versatile approach to greatly enhance the performance of MAPbBr3 single crystal photodetector and highlights the immense potential of the perovskite photodetector for health monitoring technologies by the reflectance-mode PPG detection system.

Bound states in the continuum (BICs) with infinite Q factors and topological polarization charges have emerged as a pivotal platform in quantum information. The Janus BICs carrying asymmetric topological charges exhibit great potential for nonreciprocal photonics devices. Here, the topological properties of the Janus BICs are preserved while decoupled chirality is induced, which enhances the system's advantages by providing an extra degree of freedom. In contrast to previous Janus BICs, where chirality is coupled to topological charges, we achieve decoupled control through time-reversal symmetry breaking. The theory of modified nonreciprocal temporal coupled mode theory (TCMT) with perturbation is developed to describe our system, which consists of the bi-layer photonic crystals (PhCs) with symmetry and magneto-optical (MO) symmetry slabs. When time-reversal symmetry is broken, the degenerate BICs in the MO slab split into opposite chiral modes, whose chiralities are controllable through the direction and strength of the external magnetic field. By combining the simulation method, we observe the independent modulation of topological charges and chiralities in the polarization of the far field and evolution of C points with the change of separation. Our findings open pathways for applications in chirality-dependent devices and asymmetric light-matter interaction.

Achieving high-purity vortex beams (VBs) with arbitrary orbital angular momentum (OAM) in an ultracompact footprint remains a critical challenge, as conventional VB generators are constrained by weak spin-orbit coupling, high fabrication complexity, and narrow operating bandwidths. In this work, we propose an innovative design paradigm that directly encodes a continuous spiral phase profile into the rotating sides of nanoapertures. Leveraging photonic spin-orbit interaction in tailored metasurfaces, both achiral polygonal annular apertures (PAAs) and chiral equiangular spiral apertures (ESAs) support ultracompact VB generation, with the gradual addition of apertures precisely governing OAM orders (from low to high). The transmitted VBs exhibit exceptional three-dimensional amplitude-phase fidelity and high mode purity, as confirmed by Fourier analysis. Furthermore, we rigorously expand the grating vector function theory to establish a direct link between local aperture geometry and global OAM properties, providing a powerful forward-design tool for metasurface optimization. Far-field transmission measurements and scanning near-field optical microscopy (SNOM) verify that achiral apertures produce positive/negative higher-order OAM, while chiral apertures exhibit pronounced circular dichroism. These scalable, fabrication-friendly, and practical metasurfaces combine the broadband efficiency of geometric-phase optics with promising applications in information transmission, quantum entanglement, optical trapping, and on-chip photonic circuits.

The development of blue organic light-emitting diodes (OLEDs) remains constrained by simultaneously achieving high luminous efficiency and operational stability. Herein, we systematically explore the electroluminescent performances and exciton dynamics of blue OLEDs employing the hot-exciton material PAC and the multiple-resonance thermally activated delayed fluorescence (MR-TADF) emitter v-DABNA. Direct doping of v-DABNA into PAC enables efficient F & ouml;rster resonance energy transfer (FRET) but causes severe triplet quenching due to the low triplet energy of PAC, resulting in limited device efficiency. To resolve this issue, we propose a high-lying triplet (T-n)-mediated multi-channel sensitization (HTEMS) strategy, which integrates the ultrafast high-lying reverse intersystem crossing characteristics of the hot-exciton material with spatial segregation of exciton recombination and emission domains. This design effectively suppresses triplet energy back-transfer while enables efficient FRET and T-n-mediated Dexter energy transfer. An impressively high external quantum efficiency to 15.0% with trivial roll-off was achieved by integrating triplet-triplet annihilation exciton recycling strategy. Further deuteration engineering prolonged lifetime (LT90, the luminance dropped to 90% of initial value at 1000 cd m(-2)) to among the highest values of v-DABNA-based devices, with CIEy < 0.20. This work overcomes the intrinsic efficiency-stability trade-off in blue emission, offering a robust strategy for high-performance blue OLEDs.

Both seawater flow velocity and salinity are critical parameters in marine environmental observation. Accurately achieving simultaneous measurement of these two parameters remains a challenge in oceanographic monitoring. This study innovatively developed a sensing unit (MMZI-T) that integrates a microfiber coaxial Mach-Zehnder interferometer (MMZI) with both strain responsiveness and salinity sensitivity, coupled with a T-shaped cantilever beam, and proposes what we believe to be a novel method for simultaneous measurement of seawater flow velocity and salinity. By directly contacting seawater, the sensing unit converts the pressure effect of ocean current into stress on the cantilever beam, thereby stretching the microfiber and causing a shift in the interference spectrum, enabling flow velocity measurement. The interaction between its evanescent field and seawater enables salinity measurement. The theoretical expressions for seawater flow velocity sensitivity and salinity sensitivity were derived. Experimentally, the MMZI-T sensing unit was developed, and a measurement system based on a circulating water channel was designed, achieving simultaneous measurement of seawater flow velocity and salinity. The maximum sensitivity for seawater flow velocity measurement reached 152.6 nm/(m·s-1), and the maximum salinity sensitivity reached 0.41 nm/‰. A second-order sensitivity matrix was proposed to demodulate the dual parameters. The mean relative error (MRE) and root mean square error (RMSE) for flow velocity measurement were determined to be 3.78% and 0.009 m/s, respectively, while those for salinity measurement were 1.85% and 0.576‰. The results demonstrate the high accuracy of the MMZI-T sensing unit. Due to its small size and high sensitivity, the MMZI-T sensing unit based on a microfiber coaxial Mach-Zehnder interferometer coupled with a T-shaped cantilever is expected to play an important role in the field of simultaneous ocean flow velocity and salinity measurement.

Preventing the detachment of self-assembled molecules (SAMs) and enhancing their passivation effect on perovskites are critical challenges for improving the performance and stability of perovskite solar cells1-3. Electrodeposited SAMs provide a route to improve coverage uniformity and anchoring robustness on conductive substrates beyond the limitations of conventional solution processing. Here we use potential-cycled electrodeposition to promote molecular rearrangement and re-anchoring of SAMs, resulting in a uniform and dense layer on an indium tin oxide substrate with enhanced anchoring capability. Building on this base SAM, functional units are grown via electrochemical oxidative coupling to form tailored coupled carbazole phosphonic SAMs, yielding power conversion efficiencies of 26.8% for laboratory-scale solar cells and 21.3% for solar modules (65 cm2).

Tb-activated phosphors are crucial for achieving narrow-band green emission in modern optoelectronic devices, but their thermal and chemical instability under high power restricts practical application. In this study, we prepared a Sr0.97Ba0.02Ga2O4:0.01Tb3+ phosphor featuring low thermal quenching, which retains 80

Chiral light-matter interaction in metasurfaces has drawn considerable interest for chiral sensing and spin-selective photonics. While quasi-bound states in the continuum(quasi-BIC) metasurfaces and transition metal dichalcogenides (TMDs) exciton-polariton systems have been widely explored, their circular dichroism typically deteriorates under oblique incidence, limiting practical applications that require wide-angle operation. In this study, we propose a symmetry-broken double-cross WS2 metasurface that maintains a stable chiroptical response over a broad angular range through two geometric parameters that can be optimized quasi-independently. The internal crossing angle α controls the quasi-BIC linewidth, while the inter-rod rotation angle β tunes the handedness-dependent coupling via the combined phase α + β. The resulting circular dichroism remains robust over ±0.1 rad, with a peak value of 0.96, while the quasi-BIC resonance simultaneously couples to the WS2 A-exciton to form exciton-polaritons with a Rabi splitting of 46 meV. Coupled-mode theory and multipole decomposition reveal that the chiral response originates from electric-magnetic dipole interference. These findings establish a quasi-independent tuning strategy for angle-robust chiral exciton-polaritons, paving the way toward wide-angle chiroptical devices.

In recent years, optical skyrmions have garnered significant attention due to their unique properties and potential applications. These skyrmions, which include optical field skyrmions, optical spin skyrmions, and optical Stokes skyrmions, exhibit deep-subwavelength and topologically stable characteristics that make them highly suitable for various technological applications such as microscopy, metrology, sensing, and memory. In this context, we present a theoretical proposal for the generation of optical spin skyrmions in a tightly focused partially coherent beam. Our study delves into the behavior of these skyrmions as a function of the coherence length of the beam. Optical spin skyrmions fabricated by spin-orbit coupling of a partially coherent optical vortex are not limited by the topological charge m of the optical vortex. This investigation is particularly novel as we believe it marks the first instance where skyrmions have been identified in a partially coherent beam.

The rapid proliferation of flexible electronics requires the development of high-power, self-powered systems capable of continuous output. Moisture-electric generators (MEGs) can harvest energy from ubiquitous atmospheric moisture, offering a green and renewable energy source. However, current MEGs still face limitations in terms of current density and operational lifetime. In this study, we engineered supramolecular structures within the hydrogel to induce excluded-volume effects that disrupt the solvation shell of lithium ions. By enhancing ion dissociation, increasing cation selectivity, and raising the proportion of bound water, this design facilitates rapid cation transport and the long-term preservation of the water gradient. Consequently, the MEG unit achieved an open-circuit voltage of 1.23 V, a power density of 65.3 & micro;W cm-2, and a short-circuit current of 1.06 mA cm-2. The current density is an order of magnitude higher than that of most reported MEGs. The MEG unit can operate continuously with 0.35 mA cm-2 for over 500 hours. More importantly, the MEG arrays configured in series and parallel have been shown to power commercial sensors and to enable contact-based human-machine interactions. This work highlights advancements in high-performance MEGs and their applications in sensing, paving the way for their integration with flexible electronics.

A funnel-shaped Fabry-Perot fiber optic sensor is proposed to satisfy the demand for high-sensitivity measurement of flow velocity and temperature in ocean research. The sensor consists of an aluminum alloy membrane and optical fibers. It detects changes in the cavity length of the Fabry-Perot interferometer based on the deformation and thermal expansion effects of aluminum alloy, which are induced by seawater flow velocity and pressure. These changes shift the interference spectrum, facilitating simultaneous seawater flow velocity and temperature measurements. The flow velocity and temperature sensitivities were obtained through theoretical derivation and finite element simulation. A measurement system was constructed to assess the seawater flow velocity and temperature simultaneously. At a flow velocity of 0.45 m/s, the maximum flow velocity sensitivity reaches -20.13 nm/(m/s), with an average relative error of 4.12% compared to the theoretical sensitivity. The temperature sensitivity is obtained as 10.34 nm/degrees C, with an average relative error of 4.54% relative to the theoretical sensitivity. A sensitivity matrix dual-parameter demodulation method was employed to measure 10 different seawater flow velocities and temperatures. The results were compared with the measurements obtained via an acoustic Doppler current meter (ADV) and temperature salinity depth meter (CTD). The average relative errors for flow velocity and temperature measurements are 6.07% and 4.20%, respectively. These findings demonstrate that the funnel-shaped Fabry-Perot fiber optic sensor exhibits high sensitivity and can perform dual-parameter measurements. Thus, it is expected to play a substantial role in oceanographic measurements.

Biological vision systems excel at acquiring and processing information, but there is often a trade-off between these capabilities. For instance, mantis shrimp possess exceptional spectral sensing but poor color perception due to limited neural processing. Taking the best of both worlds, the mantis shrimp's spectral detection ability and the human-like visual processing power are integrated to achieve full-color perception. Using an aerosol-liquid-solid spraying technique, an array of high-quality, excess ion migration enhanced perovskite narrowband photodetectors spanning the ultraviolet to visible spectrum is developed. These detectors enable a computational multispectral imaging system that captures seven spectral images in one shot. A deep-learning-based color fusion network is designed to efficiently translate multispectral inputs into an RGB representation, significantly enhancing color recognition of these mantis shrimp-inspired multispectral cameras and affording the capability to overcome metamerism. These perovskite intelligent camera leverages the strengths of biological vision and demonstrate a novel approach to multispectral imaging that could advance applications in machine vision, remote sensing, and medical imaging.

Performing visual recognition and combinatorial optimization simultaneously on a single multifunctional neuromorphic computing platform offers significant advantages in terms of efficiency, real‐time processing, and integrated decision‐making. However, the advances are hindered by hardware constraints. Here, a new type of all‐electrically controlled labyrinth magnetic texture (MT) devices is reported, wherein the trainable MT can be created, manipulated, and detected efficiently and reliably at room temperature. By utilizing the spin‐orbit torque (SOT) effect, it can modulate the nonlinear magneto‐resistance of the device via a corroborated dynamic conductance matrix, mimicking the mixed short‐term and long‐term potentiation of biological synapses. The developed SOT‐MT devices excel in diverse in‐memory computing tasks, including pattern recognition and combinatorial optimization. Utilizing a cross‐bar array with single SOT‐MT devices, outstanding test accuracy is achieved over 93% on MNIST, and a success rate exceeding 95% in solving the 8‐city traveling salesman problem with the Hopfield network. Synergistic tailoring of constant and dynamic fluctuations contributes to this success. The study paves the way for dynamic network MT devices, advancing complex task processing by enabling efficient fusion of cognition and combinatorial optimization on a single neuromorphic hardware system.

This paper proposes a high-speed InGaAs/InAIAs avalanche photodiode (APD) based on a hybrid charge layer. The proposed design enables precise control of the P-mesa etching depth, effectively suppresses the edge electric field in the multiplication layer, and reduces the dark current. The high-speed performance was realized by optimizing the thickness of the transit layer. At a gain of 2.3, the device achieves a 3-dB bandwidth of 47 GHz and a responsivity of 0.73 A/W.

The transport layer in an InGaAs/InAlAs avalanche photodiode (APD) is optimized to improve bandwidth. The proposed APD achieves a bandwidth of 47 GHz at a gain of 2.3, with a responsivity of 0.724 A/W and a junction capacitance of 20 fF.

We numerically and theoretically demonstrate the simultaneous generation of polarization dependent high-order merons and skyrmions constructed by degenerate chiral Bound states in the continuum (BICs) in a magneto optical (MO) photonic crystal (PhC) slab with C 6 v symmetry. Under an external magnetic field, the degenerate BICs split into chiral eigen modes, giving rise to momentum-space topological textures characterized by non-zero orbital angular momentum (OAM) and skyrmion numbers. Meanwhile, the cross-polarized components of transmitted light give rise to skyrmionic textures that fully map the Poincaré sphere under circularly polarized illumination that carry quantized OAM charges. A rectified Hamiltonian and a non-reciprocal Temporal coupled-mode theory model (TCMT) are proposed to explain these innovative phenomena convincingly. These textures exhibit remarkable robustness against various perturbations. Our work establishes a versatile platform for generating and manipulating topological textures with potential applications in robust optical information processing and metrology.

Continuous breakthroughs have been achieved in the photoelectric conversion efficiency (PCE) of tin-based perovskite solar cells (TPSCs) in recent years. Inspired by performance improvements observed during device storage, we identified beneficial light-induced interface doping (LIID) in the TPSCs. In situ analyses using X-ray photoelectron spectroscopy and ultraviolet photoelectron spectroscopy reveal that ion migration and oxidation at the interface induce beneficial doping effects, enhancing carrier transport and significantly boosting device performance. By implementing specific illumination techniques or maximum power point tracking (MPPT) methods to achieve LIID, we increased the open-circuit voltage while maintaining a high short-circuit current, reaching a PCE of up to 14.91%. Furthermore, this efficiency was sustained at 70% of its maximum value after nearly 900 h of continuous operation. Our study introduces a novel approach to addressing energy band mismatch, paving the way for improved efficiency in tin-based perovskite solar cells.