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Dielectric metasurface evolution from bulk to monolayer by strong coupling of quasi-BICs for second harmonic boosting

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Photonics Research 2024年第4期12卷 784-792页

作者： YINONG XIE QIANTING CHEN JIN YAO XUEYING LIU ZHAOGANG DONG JINFENG ZHU Institute of Electromagnetics and Acoustics and Key Laboratory of Electromagnetic Wave Science and Detection Technology Xiamen UniversityXiamen 361005China Shenzhen Research Institute of Xiamen University Shenzhen 518057China Department of Electrical Engineering City University of Hong KongHong Kong 999077China Institute of Materials Research and Engineering(IMRE) Agency for ScienceTechnology and Research(A*STAR)Singapore 138634Singapore Department of Materials Science and Engineering National University of SingaporeSingapore 117575Singapore

2D materials are promising candidates as nonlinear optical components for on-chip devices due to their ultrathin structure. In general, their nonlinear optical responses are inherently weak due to the short interaction thickness with light. Recently, there has been great interest in using quasi-bound states in the continuum (q-BICs) of dielectric metasurfaces, which are able to achieve remarkable optical near-field enhancement for elevating the second harmonic generation (SHG) emission from 2D materials. However, most studies focus on the design of combining bulk dielectric metasurfaces with unpatterned 2D materials, which suffer considerable radiation loss and limit near-field enhancement by high-quality q-BIC resonances. Here, we investigate the dielectric metasurface evolution from bulk silicon to monolayer molybdenum disulfide (MoS2), and discover the critical role of meta-atom thickness design on enhancing near-field effects of two q-BIC modes. We further introduce the strongcoupling of the two q-BIC modes by oblique incidence manipulation, and enhance the localized optical field on monolayer MoS2dramatically. In the ultraviolet and visible regions, the MoS2SHG enhancement factor of our design is 105times higher than that of conventional bulk metasurfaces, leading to an extremely high nonlinear conversion efficiency of 5.8%. Our research will provide an important theoretical guide for the design of high-performance nonlinear devices based on 2D materials.

关键词： monolayer harmonic quasi

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Observation of maximal intrinsic chirality empowered by dual quasi-bound states in the continuum in a planar metasurface

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Photonics Research 2024年第2期12卷 244-252页

作者： XIN QI JIAJU WU FENG WU SONG ZHAO CHAO WU YUEYANG MIN MINA REN YUFEI WANG HAITAO JIANG YUNHUI LI ZHIWEI GUO YAPING YANG WANHUA ZHENG HONG CHEN YONG SUN MOE Key Laboratory of Advanced Micro-Structured Materials School of Physics Science and EngineeringTongji UniversityShanghai 200092China School of Optoelectronic Engineering Guangdong Polytechnic Normal UniversityGuangzhou 510665China l3 Shanghai Key Laboratory of Special Artificial Microstructure Materials and Technology School of Physics Science and EngineeringTongji UniversityShanghai 200092China Department of Electrical Engineering Tongji UniversityShanghai 201804China State Key Laboratory on Integrated Optoelectronics Institute of SemiconductorsChinese Academy of SciencesBeijing 100083China

Metasurfaces with spin-selective transmission play an increasingly critical role in realizing optical chiral responses,especially for strong intrinsic chirality,which is limited to complex three-dimensional geometry.In this paper,we propose a planar metasurface capable of generating maximal intrinsic chirality and achieving dual-band spinselective transmission utilizing dual quasi-bound states in the continuum(quasi-BICs)caused by the structural symmetry breaking.Interestingly,the value of circular dichroism(CD)and the transmittance of two kinds of circular polarization states can be arbitrarily controlled by tuning the asymmetry parameter.Remarkable CD approaching unity with the maximum transmittance up to 0.95 is experimentally achieved in the dual band.Furthermore,assisted by chiral BICs,the application in polarization multiplexed near-field image display is also exhibited.Our work provides a new avenue to flexibly control intrinsic chirality in planar structure and offers an alternative strategy to develop chiral sensing,multiband spin-selective transmission,and high-performance circularly polarized wave detection.The basic principle and design method of our experiments in the microwave regime can be extended to other bands,such as the terahertz and infrared wavelengths.

关键词： planar intrinsic quasi

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Tuning exciton dynamics by the dielectric confinement effect in quasi-two-dimensional perovskites

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Photonics Research 2024年第3期12卷 563-570页

作者： MINGHUAN CUI CHAOCHAO QIN YUANZHI JIANG SHICHEN ZHANG CHANGJIU SUN MINGJIAN YUAN YONGGANG YANG YUFANG LIU Henan Key Laboratory of Infrared Materials&Spectrum Measures and Applications Henan Normal UniversityXinxiang 453007China Key Laboratory of Advanced Energy Materials Chemistry(Ministry of Education) College of ChemistryNankai UniversityTianjin 300071China Institute of Physics Henan Academy of SciencesZhengzhou 450046China

The dielectric confinement effect plays an essential role in optoelectronic devices.Existing studies on the relationship between the dielectric confinement and the photoelectric properties are inadequate.Herein,three organic spacers with different dielectric constants are employed to tune the exciton dynamics of quasi-two-dimensional(quasi-2D)Ruddlesden–Popper perovskite films.Femtosecond transient absorption spectroscopy reveals that the small dielectric constant ligand enables a weak dynamic disorder and a large modulation depth of the coherent phonons,resulting in a more complete energy transfer and the inhibition of a trap-mediated nonradiative recombination.Additionally,the increase in the bulk-ligand dielectric constant reduces the corresponding exciton binding energy and then suppresses the Auger recombination,which is beneficial for high-luminance lightemitting diodes.This work emphasizes the importance of dielectric confinement for regulating the exciton dynamics of layered perovskites.

关键词： dielectric perovskite quasi

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Chiral forces in longitudinally invariant dielectric photonic waveguides

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Photonics Research 2024年第3期12卷 431-443页

作者： JOSEP MARTÍNEZ-ROMEU IAGO DIEZ SEBASTIAN GOLAT FRANCISCO J.RODRÍGUEZ-FORTUÑO ALEJANDRO MARTÍNEZ Nanophotonics Technology Center Universitat Politècnica de ValènciaValencia 46022Spain Department of Physics King’s College LondonLondon WC2R 2LSUK

We calculate numerically the optical chiral forces in rectangular cross-section dielectric waveguides for potential enantiomer separation.Our study considers force strength and time needed for separating chiral nanoparticles,mainly via quasi-TE guided modes at short wavelengths(405 nm)and the 90°-phase-shifted combination of quasi-TE and quasi-TM modes at longer wavelengths(1310 nm).Particle tracking simulations show successful enantiomer separation within two seconds.These results suggest the feasibility of enantiomeric separation of nanoparticles displaying sufficient chirality using simple silicon photonic integrated circuits,with wavelength selection based on the nanoparticle size.

关键词： dielectric forces quasi

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quasi-Two-Dimensional Nature of High-Tc Superconductivity in Iron-Based(Li,Fe)OHFeSe

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Chinese Physics Letters 2022年第12期39卷 77-83页

作者：李栋刘樾鲁邹有为李沛岭张宇航马晟刘家利卢佶虎张华刘广同周放董晓莉赵忠贤 Beijing National Laboratory for Condensed Matter Physics Institute of PhysicsChinese Academy of SciencesBeijing 100190China School of Physical Sciences University of Chinese Academy of SciencesBeijing 100049China Songshan Lake Materials Laboratory Dongguan 523808China Key Laboratory for Vacuum Physics University of Chinese Academy of SciencesBeijing 100049China

The intercalated iron selenide(Li,Fe)OHFeSe has a strongly layered structure analogous to the quasi-twodimensional(2D)bismuth cuprate superconductors,and exhibits both high-temperature(Tc)and topological superconductivity.However,the issue of its superconductivity dimensionality has not yet been fully investigated so far.Here we report that the quasi-2D superconductivity features,including the high anisotropyγ=151 and the associated quasi-2D vortices,are also revealed for(Li,Fe)OHFeSe,based on systematic experiments of the electrical transport and magnetization and model fittings.Thus,we establish a new vortex phase diagram for(Li,Fe)OHFeSe,which delineates an emergent quasi-2D vortex-liquid state,and a subsequent vortex-solid dimensional crossover from a pancake-like to a three-dimensional state with decreasing temperature and magnetic field.Furthermore,we find that all the quasi-2D characteristics revealed here for the high-Tciron selenide superconductor are very similar to those reported for high-Tcbismuth cuprate superconductors.

关键词： field vortex quasi

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CQFFA:A Chaotic quasi-oppositional Farmland Fertility Algorithm for Solving Engineering Optimization Problems

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Journal of Bionic Engineering 2023年第1期20卷 158-183页

作者： Farhad Soleimanian Gharehchopogh Mohammad H.Nadimi-Shahraki Saeid Barshandeh Benyamin Abdollahzadeh Hoda Zamani Department of Computer Engineering Urmia BranchIslamic Azad UniversityUrmia969Iran Faculty of Computer Engineering Najafabad BranchIslamic Azad UniversityNajafabad517Iran Big Data Research Center Najafabad BranchIslamic Azad UniversityNajafabad517Iran Afagh Higher Education Institute Urmia969Iran

Farmland Fertility Algorithm(FFA)is a recent nature-inspired metaheuristic algorithm for solving optimization problems.Nevertheless,FFA has some drawbacks:slow convergence and imbalance of diversification(exploration)and intensification(exploitation).An adaptive mechanism in every algorithm can achieve a proper balance between exploration and exploitation.The literature shows that chaotic maps are incorporated into metaheuristic algorithms to eliminate these drawbacks.Therefore,in this paper,twelve chaotic maps have been embedded into FFA to find the best numbers of prospectors to increase the exploitation of the best promising solutions.Furthermore,the quasi-Oppositional-Based Learning(QOBL)mechanism enhances the exploration speed and convergence rate;we name a CQFFA algorithm.The improvements have been made in line with the weaknesses of the FFA algorithm because the FFA algorithm has fallen into the optimal local trap in solving some complex problems or does not have sufficient ability in the intensification component.The results obtained show that the proposed CQFFA model has been significantly improved.It is applied to twenty-three widely-used test functions and compared with similar state-of-the-art algorithms statistically and visually.Also,the CQFFA algorithm has evaluated six real-world engineering problems.The experimental results showed that the CQFFA algorithm outperforms other competitor algorithms.

关键词： Nature-inspired algorithm Farmland fertility algorithm Chaotic maps quasi Engineering optimization problems

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Optofluidic transport and assembly of nanoparticles using an all-dielectric quasi-BIC metasurface

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Light(Science & Applications) 2023年第9期12卷 1771-1781页

作者： Sen Yang Justus C.Ndukaife Department of Electrical and Computer Engineering Vanderbilt UniversityNashvilleTNUSA Interdisciplinary Materials Science Vanderbilt UniversityNashvilleTNUSA Full list of author information is available at the end of the article

Manipulating fluids by light at the micro/nanoscale has been a long-sought-after goal for lab-on-a-chip applications.Plasmonic heating has been demonstrated to control microfluidic dynamics due to the enhanced and confined light absorption from the intrinsic losses of metals.Dielectrics,the counterpart of metals,has been used to avoid undesired thermal effects due to its negligible light absorption.Here,we report an innovative optofluidic system that leverages a quasi-BIC-driven all-dielectric metasurface to achieve subwavelength scale control of temperature and fluid motion.Our experiments show that suspended particles down to 200 nanometers can be rapidly aggregated to the center of the illuminated metasurface with a velocity of tens of micrometers per second,and up to millimeter-scale particle transport is demonstrated.The strong electromagnetic field enhancement of the quasi-BIC resonance increases the flow velocity up to three times compared with the off-resonant situation by tuning the wavelength within several nanometers range.We also experimentally investigate the dynamics of particle aggregation with respect to laser wavelength and power.A physical model is presented and simulated to elucidate the phenomena and surfactants are added to the nanoparticle colloid to validate the model.Our study demonstrates the application of the recently emerged all-dielectric thermonanophotonics in dealing with functional liquids and opens new frontiers in harnessing non-plasmonic nanophotonics to manipulate microfluidic dynamics.Moreover,the synergistic effects of optofluidics and high-Q all-dielectric nanostructures hold enormous potential in high-sensitivity biosensing applications.

关键词： dielectric quasi negligible

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quasi-Two-Dimensional Diffusion in Adherent Cells Revealed by Three-Dimensional Single Quantum Dot Tracking

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Chinese Physics Letters 2020年第7期37卷 130-136页

作者：江超李波窦硕星王鹏业李辉 Beijing National Laboratory for Condensed Matter Physics and Laboratory of Soft Matter Physics Institute of PhysicsChinese Academy of SciencesBeijing 100190China School of Physical Sciences University of Chinese Academy of SciencesBeijing 100049China Songshan Lake Materials Laboratory Dongguan 523808China School of Systems Science Beijing Normal UniversityBeijing 100875China

Intracellular diffusion is critical for molecule translocation in cytoplasm and mediates many important cellular processes.Meanwhile,the diffusion dynamics is affected by the heterogeneous cytoplasm.Previous studies on intracellular diffusion are mainly based on two-dimensional(2 D)measurements under the assumption that the three-dimensional(3 D)diffusion is isotropic.However,the real behaviors of 3 D diffusion of molecules in cytoplasm are still unclear.Here,we have built a 3 D single-particle tracking(SPT)microscopy and studied the 3 D diffusion of quantum dots(QDs)in adherent A549 cells.Notably,we found that the intracellular diffusion of QDs is quasi-2 D,with the axial motion being severely confined.Further investigations demonstrated that disrupting the cytoskeleton component or endoplasmic reticulum(ER)does not alter the quasi-2 D diffusion pattern,although ER reduces the diffusion rates and slightly relieves the constraint in the axial diffusion.The preferred quasi-2 D diffusion is quite robust and attributed to the complex cytoarchitectures in the flat adherent cells.With the aid of 3 D SPT method,the quasi-2 D diffusion in cells was revealed,shedding new light on the physical nature of cytoplasm.

关键词： diffusion quasi Quantum

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1D quasi-bound states in the continuum with large operation bandwidth in theω~k space for nonlinear optical applications

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Photonics Research 2022年第7期10卷 1575-1581页

作者： KAILI SUN HUI JIANG DMITRY ABYKOV VIEN VAN URIEL LEVY YANGJIAN CAI ZHANGHUA HAN Shandong Provincial Key Laboratory of Optics and Photonic Devices Center of Light Manipulation and ApplicationsSchool of Physics and ElectronicsShandong Normal UniversityJinan 250358China Image Processing Systems Institute—Branch of the Federal Scientific Research Centre“Crystallography and Photonics”of Russian Academy of Sciences Samara 443001Russia Department of Electrical and Computer Engineering University of AlbertaEdmontonAlberta T6G 2V4Canada Department of Applied Physics and Center for Nanoscience and NanotechnologyThe Hebrew University of JerusalemJerusalemIsrael

The phenomenon of bound state in the continuum(BIC)with an infinite quality factor and lifetime has emerged in recent years in photonics as a new tool to manipulate light-matter interactions.However,most of the investigated structures only support BIC resonances at very few discrete points in theω~k space.Even when the BIC is switched to a quasi-BIC(QBIC)resonance through perturbation,its frequency will still be located within a narrow spectral band close to that of the original BIC,restricting their applications in many fields where random or multiple input frequencies beyond the narrow band are required.In this work,we demonstrate that a new set of QBIC resonances can be supported by using a special binary grating consisting of two alternatingly aligned ridge arrays with the same period and zero-approaching ridge width difference on a slab waveguide.These QBIC resonances are distributed continuously over a broad band along a line in theω~k space and can thus be considered as 1 D QBICs.With the Q factors generally affected by the ridge difference,it is now possible to arbitrarily choose any frequencies on the dispersion line to achieve significantly enhanced light-matter interactions,facilitating many applications where multiple input wavelengths are required;e.g.,sum or difference frequency generations in nonlinear optics.

关键词： quasi nonlinear narrow

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Steerable merging bound states in the continuum on a quasi-flatband of photonic crystal slabs without breaking symmetry

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光子学研究:英文版 2023年第7期11卷 1262-1274页

作者： XIN QI JIAJU WU FENG WU MINA REN QIAN WEI YUFEI WANG HAITAO JIANG YUNHUI LI ZHIWEI GUO YAPING YANG WANHUA ZHENG YONG SUN HONG CHEN MOE Key Laboratory of Advanced Micro-structured Materials School of Physics Sciences and EngineeringTongji UniversityShanghai 200092China School of Optoelectronic Engineering Guangdong Polytechnic Normal UniversityGuangzhou 510665China State Key Laboratory on Integrated Optoelectronics Institute of SemiconductorsChinese Academy of SciencesBeijing 100083China Department of Electrical Engineering Tongji UniversityShanghai 201804China

Optical resonators with high quality(Q)factors are paramount for the enhancement of light–matter interactions in engineered photonic structures,but their performance always suffers from the scattering loss caused by fabrication imperfections.Merging bound states in the continuum(BICs)provide us with a nontrivial physical mechanism to overcome this challenge,as they can significantly improve the Q factors of quasi-BICs.However,most of the reported merging BICs are found atΓpoint(the center of the Brillouin zone),which intensively limits many potential applications based on angular selectivity.To date,studies on manipulating merging BICs at off-Γpoint are always accompanied by the breaking of structural symmetry that inevitably increases process difficulty and structural defects to a certain extent.Here,we propose a scheme to construct merging BICs at almost an arbitrary point in momentum space without breaking symmetry.Enabled by the topological features of BICs,we merge four accidental BICs with one symmetry-protected BIC at theΓpoint and merge two accidental BICs with opposite topological charges at the off-Γpoint only by changing the periodic constant of a photonic crystal slab.Furthermore,the position of off-Γmerging BICs can be flexibly tuned by the periodic constant and height of the structure simultaneously.Interestingly,it is observed that the movement of BICs occurs in a quasi-flatband with ultra-narrow bandwidth.Therefore,merging BICs in a tiny band provide a mechanism to realize more robust ultrahigh-Q resonances that further improve the optical performance,which is limited by wide-angle illuminations.Finally,as an example of application,effective angle-insensitive second-harmonic generation assisted by different quasi-BICs is numerically demonstrated.Our findings demonstrate momentum-steerable merging BICs in a quasi-flatband,which may expand the application of BICs to the enhancement of frequency-sensitive light–matter interaction with angular selectivity.

关键词： quasi symmetry breaking

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