Solution-processable quasi-2D perovskites are regarded as promising candidates for laser gain media due to their superior exciton binding energy and stability compared to their 3D counterparts. However, quasi-2D perovskites produced through conventional methods often display a distribution of n-value phases, arising from the necessity of multiple precursors to react. The presence of impurity phases may introduce interfacial defects and energetic disorder, which can hinder charge injection into the desired emission centers. In this study, we present the first demonstration of stimulated emission from a phase-pure quasi-2D perovskite achieved through a solvent-sieving method for selective phase removal. This approach enables the dynamic purification of quasi-2D perovskites (n = 8) and significantly lowers the threshold for amplified spontaneous emission. X-ray diffraction and ultraviolet-visible characterization reveal a nearunity n = 8 phase (99.85

Filamentation has garnered significant interest for its potential physical properties, complexity, and practicality. However, achieving controllable and customizable filamentation is a major challenge. Here, a new method based on the topological properties of polarization singularities (PSs) is proposed and experimentally verified to generate robust filament arrays. It is found that the number of filaments is directly linked to the spatial topological distribution of PSs, allowing for the generation of controllable filaments. Furthermore, the position and interval of the filaments can be flexibly controlled by modulating the PS spacing. Remarkably, the resulting filament patterns exhibit a robust feature insensitive to the random noise, a property attributed to the topological robustness of PSs. The physical mechanism governing the interaction between multisingularity vector optical fields (MS-VOFs) and Kerr media is also elucidated. Our findings may open new avenues for exploring the interaction between PSs and nonlinear media and hold promise for applications in optical manipulation, laser processing, and other areas.

Phase-gradient metasurfaces based on guided-mode resonances achieve wavefront shaping with high resolution in both spatial and spectral dimensions, leveraging coherent near-field interactions between adjacent meta-atoms. Although structural perturbations typically distort spectral resonances, harnessing such distortions offers a promising route for novel wavefront control. In this work, we propose a non-Hermitian system consisting of a plasmonic metasurface coupled to an optical waveguide, which supports guided-mode resonances and enables the realization of exceptional points. The emergence of these exceptional points exhibits a pronounced angular dependence, originating from orientation-sensitive neighboring coupling effects that induce spectral fluctuations during rotation. We show that spectral perturbations approaching exceptional points modulate the Pancharatnam-Berry phase accumulation. Through metalens design, spin-selective transitions between focusing and diverging are achieved across different wavelength bands. These findings provide an effective strategy for achieving novel wavefront shaping and polarization control.

Colloidal quantum dots (QDs) are promising optical gain materials that require a reduction in the threshold to reach their full potential. While QD charging theoretically reduces the threshold to zero, its effectiveness has been limited by strong Auger recombination and unstable charging. In this study, we theoretically determine the optimal combination of charging number and Auger recombination to minimize the lasing threshold. Experimentally, we develop stable, self-charged perovskite quantum rods (QRs) as an alternative to QDs via the state engineering and Mn (manganese) doping strategy. A two-order-of-magnitude reduction in nonradiative Auger recombination enables QRs to support a charging number of up to 6. We then achieve QR liquid lasing with a sub- 1 / 10 exciton threshold (an average of 0.098 excitons per QR) using 5-nanosecond pulse pumping. This threshold is exceptionally low among all reported QD lasers. These achievements demonstrate the potential of specially engineered QRs as excellent gain media and pave the way for their applications.

A major challenge in plasmonic lattice research is the limited flexibility for independently controlling multiple surface lattice resonances with high quality factors within a single array, as conventional single-nanoparticle and isotropic dimer designs lack independent control degrees of freedom, including incident light polarization and inter-rod displacement within nanorod dimers, and thus cannot support selective mode excitation or continuous Q-factor tuning. To address this, we propose a gold nanorod dimer array where each unit cell contains two anisotropic rods. By selecting the incident polarization and designing the relative in‑plane displacements between the rods, the array allows precise manipulation of collective surface lattice resonances. It is shown that the surface lattice resonance mode can reach a Q-factor exceeding 700 with good robustness. Symmetric displacement further enables complementary switching, where the low-order and the high-order lattice resonances are selectively activated or suppressed depending on nanorod positioning at antinodes or nodes of the lattice waves. Leveraging these dual high-Q modes, the array achieves theoretical refractive index sensitivities of 456 nm/RIU and 653 nm/RIU, with corresponding figures of merit of 98 and 409, respectively, enabling self-referenced, high-performance biochemical sensing and multi-wavelength nanophotonic applications.

With the rapid advancement of the information era, the demand for device integration and intelligent sensing has grown significantly. Traditional three-dimensional (3D) materials are constrained by lattice mismatch and interfacial defects, and their limited functionalities often require bulky auxiliary components. In contrast, the rich family of two-dimensional (2D) materials eliminates lattice-matching constraints and offers unique light-matter interactions, paving the way for compact and novel intelligent sensing technologies. However, large-area fabrication and precise layer alignment in all-2D systems remain major challenges that hinder device scalability. Given that the performance and manufacturing capabilities of 2D materials cannot replace traditional semiconductors (such as Si), they are more likely to be heterogeneously integrated with conventional 3D semiconductors. 2D/3D heterojunctions combine the distinctive optoelectronic properties of 2D materials with the mature electronic functionalities of 3D semiconductors. In this work, we present recent advances in 2D/3D heterojunction photodetectors, with a particular emphasis on the underlying physical mechanisms, including band structure design, interface optimization, external-field coupling, and novel topological configurations. Meanwhile, we also explore emerging opportunities for CMOS-compatible and intelligent sensing optoelectronic systems. Finally, the challenges and future research directions toward the integrated development of 2D/3D heterojunctions are discussed.

Surface lattice resonances (SLRs) in plasmonic nanoparticle arrays provide narrow optical features that are sensitive to lattice periodicity and the surrounding refractive index. Although mechanical tuning, refractive-index modulation, and polarization-dependent SLR responses have each been investigated previously, comparative channel-resolved studies of how orthogonal SLR channels in the same flexible anisotropic lattice respond to these external perturbations remain limited. Here, we fabricate rectangular Au nanodisk lattices on flexible PDMS substrates and investigate their polarization-resolved transmittance spectra under uniaxial mechanical strain and liquid-superstrate refractive-index variation. Under x-axis stretching up to 5%, the y-polarized resonance redshifts from 1269 nm to approximately 1335 nm, whereas the x-polarized resonance blueshifts from 1167 nm to approximately 1141 nm. Under y-axis stretching, the x-polarized resonance redshifts from 1167 nm to approximately 1225 nm, while the y-polarized resonance blueshifts from 1269 nm to approximately 1247 nm. Increasing the liquid-superstrate refractive index from 1.39 to 1.49 redshifts the resonances, with fitted sensitivities of approximately 359 nm/RIU and 305 nm/RIU for the two channels. In addition to resonance shifts, the linewidths and quality factors exhibit channel-dependent evolution under strain, consistent with strain-dependent changes in radiative-loss suppression and spectral inhomogeneity. The distinct strain- and refractive-index-induced shifts expand the accessible tuning space and may support multi-parameter calibration. These results provide useful design insights for flexible SLR-based optical filters, refractive-index sensors, and reconfigurable nanophotonic devices.

Periodic one‐dimensional gratings are fundamental components for light field modulation and resonance coupling in micro/nano-photonic devices, yet simple and low‐cost fabrication of gratings with simultaneously tunable period and height remains challenging. We report a simple, low-cost method to simultaneously increase the period and height of one-dimensional PDMS gratings by combining mechanical stretching with oxygen plasma treatment. Stretching perpendicular to the grating lines enlarges the period but reduces the height. Subsequent plasma treatment forms a silica-like surface layer. Upon release, stress mismatch drives a significant height increase without introducing defects. Using a DVD grating as master, the period is expanded from 725 nm to 1348 nm and the height from 132 nm to 276 nm. With a CD master, periods up to ∼3 μm and heights up to 236 nm are achieved. The effects of treatment time and stretching ratio are investigated, and a diffraction-based method is established for rapid height estimation. Iterative replication further extends the tunable range. This approach enables independent control of both period and height, facilitating development of tunable micro/nano-photonic devices.

Arrays of noble metal nanoparticles supporting surface lattice resonances (SLRs) are promising for advanced nanophotonic devices, yet robust control and tuning of multiple resonant modes remain challenging. In this work, we fabricate overlapping gold nanodisk arrays with different lattice periods, enabling the simultaneous excitation of multiple well-defined SLRs within a single platform. By comparing transmission spectra of overlapping and isolated arrays, together with calculated near-field distributions, we confirm that each SLR is primarily governed by the structural parameters of its corresponding array. Remarkably, large variations in the relative shifts of the overlapping arrays lead to only negligible spectral changes, indicating weak inter-mode coupling and strong fabrication tolerance in this hybrid configuration. Benefiting from the coexistence of multiple high-quality resonances, the structure exhibits good multi-wavelength refractive-index sensing with a maximum sensitivity of 755 nm/RIU and a figure of merit up to 101, while maintaining stable resonance characteristics under non-ideal structural and environmental conditions. Furthermore, transferring the arrays onto a flexible substrate further enables dynamic and reversible tuning of multiple SLRs via mechanical stretching, providing active control of a complex multi-resonant system. Overall, overlapping plasmonic lattices emerge as a robust multi-band platform that bridges theoretical design and practical implementation for sensing and reconfigurable nanophotonic devices.

Filamentation has attracted extensive attention due to its potential physical properties, complexity, and practicality. However, it is challenging to accurately steer multiple filaments (e.g. number, orientation, and interval) at one time. We propose anew method for achieving controllable and robust filaments by using the full Poincar & eacute; (FP) beam, which both carries inhomogeneous polarization and phase information. It is uncovered that the controllable filaments and orbital angular momentum (OAM) flux can be simultaneously achieved by alternating the relative amplitude and topological charge of the two orthogonal Laguerre-Gaussian (LG) components. More interestingly, we find that variations in the sign of the OAM flux exactly correspond to the filament patterns. In addition, the underlying physical mechanism is elucidated by nonlinear refractive phase shift resulting from the interaction between FP beam and Kerr media. The presented work opens up new windows for controlling filaments and will promote exciting possibilities for exploring OAM in applications.

Position-sensitive photodetectors (PSDs) have been widely used for seamless, high-resolution light tracking, but applications such as aerospace and prolonged field operations require stable performance in extreme environments. Conventional PSDs, typically based on the lateral photovoltaic effect of silicon or other semiconductor junctions, are prone to radiation damage and material degradation, limiting their reliability under harsh conditions. Silicon carbide (SiC), with its wide bandgap, high mobility, low defect density, and strong resistance to radiation damage, offers a promising alternative for developing robust detectors. In this work, we present a PSD based on undoped 4H-SiC, designed with a simple vertical structure that eliminates the need for complex multi-interface architectures. The device demonstrates excellent performance, including a light on-off ratio exceeding 103 under sub-milliwatt illumination, spatial resolution of ∼0.1 μm, and fast response times of ∼10 μs (rise) and ∼6.3 μs (fall). It also exhibits remarkable stability under γ-ray irradiation (300 krad) with minimal photocurrent variation, making it suitable for accurate position tracking in radiation-prone environments. This work highlights the potential of 4H-SiC-based PSDs for advanced sensing applications that demand both high performance and resilience in extreme environments.

We report the first observation of illumination-induced transparency (IIT) in two-dimensional Ruddlesden-Popper halide perovskite single crystals. Under continuous excitation, the crystal becomes progressively transparent to its own photoluminescence (PL), particularly near the absorption edge where reabsorption is initially strong. The effect evolves over seconds, shows an excitation fluence threshold and persistence. We attribute IIT to the activation of lattice energy reservoirs (LERs), which are spatially non-uniform nanodomains that store phonon energy as elastic potential under optical excitation. These LERs enable subgap carrier upconversion thus generate photon gain that compensates the intrinsic absorption. The effect reveals a previously unrecognized optoelectronic behavior in 2D perovskites, governed by dynamic lattice–carrier interactions rather than electronic band filling. This phenomenon demonstrates a new light–matter interaction regime in perovskites and highlights LERs as optically accessible energy gateways. Our findings suggest new routes toward photon-recycling, upconversion, and reconfigurable photonic materials based on soft-lattice semiconductors.

Vector spatiotemporal optical vortices (V-STOVs), which combine spatiotemporal wave packet with a vector polarization structure, have attracted significant attention due to their unique physical property, structural diversity, and potential applications in ultrafast optics. In the tightly focusing regime, spatiotemporal optical vortices (STOVs) are expected to exploit novel properties through spatiotemporal coupling. However, it remains a challenge to achieve a stable and tunable focal field of STOV in a high numerical aperture (NA) system. Here, a new tightly focusing method based on V-STOV encoding is proposed, and the synergistic tuning of pulse width, vector polarization, and vortex order on the STOV focal field is achieved to our knowledge. It is uncovered that the polarization spatial structure of V-STOV plays a pivotal role in determining the rich and exotic features of the focal field. Interestingly, thenquantitative evaluation result reveals that the focal field distortion of V-STOV is smaller than scalar STOV (S-STOV), which is attributed to its spatiotemporal coupling characteristics. In addition, it is found that both the intensity and the transverse orbital angular momentum (OAM) distributions of the STOV exhibit a periodic evolution over time. The periodicity remains unchanged even during ultrafast pulse compression. This work may provide a new avenue for ultrafast spatiotemporal tuning of light, with potential applications in high-resolution imaging, particle manipulation, and laser material processing.

Arrays composed of metal nanoparticles can generate multiple surface lattice modes, which effectively suppress radiative losses and enhance light-matter interactions at the nanoscale across multiple spectral ranges. However, achieving multiple surface lattice modes with large tunability over a broad spectral range remains a challenge. This paper proposes a mechanism for exciting multiple surface lattice modes based on hybrid metal/dielectric/metal nanodisk arrays. The study demonstrates that the coupling between the electric and magnetic dipoles of the hybrid nanodisks and the lowest-order Rayleigh anomaly of the array enables the system to present optical responses similar to those of high-refractive-index dielectric nanostructure arrays, thereby effectively exciting both electric and magnetic dipole surface lattice modes. Additionally, the research reveals that the electric quadrupole mode of the hybrid nanodisks can also effectively contribute to surface lattice mode excitation. By adjusting the array periodicity, multiple surface lattice modes with significant tunability can be simultaneously generated in the visible and near-infrared spectral regions. This design approach based on hybrid nanodisk arrays not only provides efficient control over the excitation of multiple surface lattice modes but also suppresses radiative losses, expanding their potential applications in white light nanolasers, optical nonlinear effects, and other multi-wavelength nanophotonic devices.

The anisotropic Kerr media with complex structure offers anew paradigm to forming diverse filamentation patterns. A great challenge and expectation is to flexibly modulate the distribution of filaments. Herein, we propose and demonstrate that controllable filamentation patterns in cubic crystals can be achieved by the synergy of crystal orientation and polarization structure. The results reveal that the self-focusing patterns exhibit high symmetry when the vector optical fields (VOFs) are incident along the crystal's principal axis. Interestingly, once the incident orientation is changed, the filament intervals will be unevenly distributed. Additionally, the synergy of crystal orientation and polarization structure actively breaks the symmetry, making the resulting collapse patterns nearly immune to the extra random noise. Finally, we derive the analytical solution for the positions of the filaments and elucidate the underlying physical mechanisms. The findings may have potential in micro-nano fabrication, wave-guides, and other related applications.

Colloidal quantum dots (QDs) are promising optical gain materials that require further threshold reduction to realize their full potential. While QD charging theoretically reduces the threshold to zero, its effectiveness has been limited by strong Auger recombination and unstable charging. Here we theoretically reveal the optimal combination of charging number and Auger recombination to minimize the lasing threshold. Experimentally, we develop stable self-charged perovskite quantum rods (QRs) as an alternative to QDs via state engineering and Mn-doping strategy. An unprecedented two-order-of-magnitude reduction in nonradiative Auger recombination enables QRs to support a sufficient charging number of up to 6. The QR liquid lasing is then achieved with a near-zero threshold of 0.098 using quasi-continuous pumping of nanosecond pulses, which is the lowest threshold among all reported QD lasers. These achievements demonstrate the potential of the specially engineered QRs as an excellent gain media and pave the way for their prospective applications.

Palladium nanoparticles boast large specific surface area,high catalytic efficiency,and excellent electrochemical performance,making them highly promising for applications in photocatalysis and light sensing.Improving the interaction among these nanoparticles and the light field is crucial for enhancing optical device performance.In this study,palladium nanoparticle superlattice thin films were prepared using a self-assembly method.The superlattice polariton mode,which is based on excitation enhancement,significantly improved the concentration of light field energy on the palladium nanoparticle structure.Both experimental and calculated transmittance/reflectance spectra indicated that the as-prepared palladium nanoparticle superlattice effectively excites polariton modes.As the number of superlattice film layers increases,the same order polariton modes experience a redshift,while higher-order polariton modes are generated.Notably,this superlattice structure creates enhanced local fields at the intervals between nanoparticles.Compared to discrete palladium nanoparticles,the local field enhancement factor of the superlattice structure is approximately doubled,achieving more effective focusing of incident field energy.This study offers valuable insights for designing high-performance photocatalytic and light sensing devices.

Objective All-inorganic CsPbX3 perovskite quantum dots (QDs) are ideal materials for high-quality single-photon sources in quantum information applications, as the performance of single-photon sources is closely related to the size of perovskite QDs. However, the lack of effective methods to reduce the size of CsPbX3 QDs remains one of the major obstacles to achieving single-photon emission. In this study, we employ an efficient and low-cost doping synthesis strategy, directly introducing ammonium bromide (NH4Br) into the lead precursor via the hot-injection method, successfully preparing CsPbBr3 perovskite QDs. By utilizing NH4Br to regulate crystal growth kinetics and passivate surface defects, we effectively suppress the Ostwald ripening process, significantly reducing the average size from the original 10.07 nm to 6.87 nm while improving size uniformity. The size reduction enhances the quantum confinement effect, leading to a blue shift in the photoluminescence (PL) emission peak from 520 nm (undoped) to 505 nm. Additionally, autocorrelation tests reveal that the g2(0) value of the doped QDs decreases from 0.45 to 0.22, which indicates a significant improvement in single-photon purity. We present an innovative and straightforward synthesis strategy, successfully producing CsPbBr3 perovskite QDs with a narrow size distribution. The incorporation of NH4Br enhances the single-photon purity of the QDs, which provides an ideal material system for single-photon emission applications and lays an important foundation for their commercialization. Methods In our study, CsPbBr3 QDs, and NH4Br-doped CsPbBr(3 )QDs are synthesized using the hot-injection method to achieve size reduction and improved size uniformity. The synthesis process consists of two main steps. Firstly, the cesium precursor is prepared by heating a mixture of cesium carbonate, oleic acid, and 1-octadecene in an inert atmosphere at 120 degrees C for 2 h, followed by increasing the temperature to 160 degrees C. The resulting solution is then cooled to room temperature and stored under sealed conditions. Secondly, the synthesis of CsPbBr3 QDs and NH4Br-doped CsPbBr3 QDs is carried out by heating a mixture of lead bromide, ammonium bromide, oleic acid, oleylamine, and 1-octadecene in an inert atmosphere for 2 h, with the temperature raised to 150 degrees C. Subsequently, 0.4 mL of cesium oleate precursor is rapidly injected. After 5 s of reaction, the mixture is immediately cooled using an ice-water bath. Well-dispersed QD solutions are obtained by high-speed centrifugation. Throughout the synthesis process, QDs with different doping concentrations are prepared by controlling the amount of ammonium bromide added. Results and Discussions The prepared NH4Br-CsPbBr3 QDs, with the Br/Pb molar ratio less than 7, exhibit a distinct decreasing trend in particle size as the Br/Pb molar ratio increases. The average particle size of CsPbBr3 QDs significantly decreases from 10.07 to 6.87 nm, which results in a blue shift of the PL emission peak from 520 nm (undoped) to 505 nm (Br/Pb molar ratio is 7). Statistical analysis of the same number of grains further shows that the particle size distribution narrows from 4-19 nm to 5.5-9 nm, which confirms that ammonium bromide doping effectively improves the morphological uniformity of the QDs. However, when the Br/Pb molar ratio exceeds 7, excess ammonium bromide disrupts the controllability of the QD morphology, which leads to distortion of the cubic structure. Therefore, the effective doping range of ammonium bromide is limited to a Br/Pb molar ratio of less than or equal to 7. Furthermore, the doping of ammonium bromide strengthens the covalent bonding of Pb-Br, which enhances the stability of the QD crystal structure and increases the quantum yield of the QDs from 31.22 % to 61.65 %, while the fluorescence lifetime extends from 1.15 ns to 2.80 ns. The reduction in QD size induced by NH4Br doping enhances the quantum confinement effect. This enhanced quantum confinement leads to a more discrete energy level structure in the QDs, which significantly reduces the probability of multiphoton emission, thereby improving the purity of single-photon emission. After doping, the second-order autocorrelation function g2(0) of the QDs decreases from the original value of 0.45 to 0.22, which indicates that ammonium bromide doping effectively improves the single-photon emission purity of the QDs. Conclusions Our study systematically reveals the effect of NH4Br doping on the size control of CsPbBr3 perovskite QDs, its intrinsic mechanisms, and the effect on single-photon properties. Experimental results show that within the doping concentration range where the Br/Pb molar ratio is less than or equal to 7, the QD size decreases in a regular pattern as the doping concentration increases, with the average particle size significantly reducing from 10.07 nm (undoped) to 6.87 nm (at a Br/Pb molar ratio of 7). More importantly, the uniformity of the doped QDs' size is improved, with the particle size distribution narrowing from 4-19 nm to 5.5-9 nm. This improvement primarily stems from the bromine-rich environment provided by ammonium bromide, which not only effectively fills the bromine vacancies on the QD surface [as confirmed by X-ray photoelectron spectroscopy (XPS) quantitative analysis, showing an increase in the Br/Pb molar ratio from 3.85 to 4.21] but also narrows the size distribution by suppressing Ostwald ripening and through the synergistic coordination of NH4+ ions with the [PbBr6](4-)octahedral structure. We find that after doping, the g2(0) value of the QDs decreases from 0.45 to 0.22, which indicates that NH4Br doping helps improve the single-photon purity of the QDs. The innovative findings of this study open new avenues for the application of perovskite crystal QDs in single-photon sources, which is of great significance for advancing the development of single-photon technology in cutting-edge fields, such as quantum communication, quantum computing, and quantum information processing.

The rapid development of optoelectronic devices presents growing challenges to information confidentiality and security. A gradient structure, capable of transmitting optical signals dependent on the incident light, is highly attractive for applications in logical operations, image sensing, and secure optical communication. In this study, composition/bandgap gradient CdS1-xSex nanowires were synthesized using a magnet-pulling source-moving chemical vapor deposition method and fabricated into high-performance photodetectors. Structural characterizations and optical investigations indicate that these band gap-gradient CdS1-xSex nanowires exhibit high crystalline quality with continuously tunable PL emissions from green to red. Bandgap-gradient CdS1-xSex nanowire photodetectors were fabricated, and their performance is remarkable in terms of a high Ion/Ioff ratio of 103, high responsivity of 89 A/W, high detectivity of 1.06 × 1013 Jones, and good switch characteristics. Additionally, optical-controlled "AND" and "OR" photoelectric logic gates are successfully implemented based on these gradient nanowire photodetectors. Finally, the single- and dual-channel optical communication systems are designed and constructed to show the applications in the security and encryption of optical communication. All of these findings highlight the potential of combining on-nanowire bandgap modulation with advanced technology and provide an effective avenue for developing multifunctional systems based on nanophotonic devices.