Polarization singularities beyond the bound states in the continuums(BICs)have garnered significant interest due to their potential for light manipulation.The conservation of topological charge has proven crucial in v...Polarization singularities beyond the bound states in the continuums(BICs)have garnered significant interest due to their potential for light manipulation.The conservation of topological charge has proven crucial in various photonic systems,and it guides the behavior of these singularities,including the generation and annihilation of BICs.This work theoretically reveals the simultaneous generation of two distinct polarization singularity types,which include off-Γaccidental BICs and Dirac-type band degeneracy points.The generation is driven by a quadratic degeneracy of symmetry-protected BICs in a photonic crystal slab.It should be noted that this is achieved through continuously tuning a geometric parameter without breaking symmetry.Importantly,the generation of both singularity types can be explained by the topological charge conservation law.This adherence ensures the stability of these singularities and allows for continuous tuning of their positions in momentum space by continuously tuning a geometric parameter while preserving symmetry.This study presents a novel framework for synthesizing and manipulating complex polarization states by combining polarization singularities from both BICs and band degeneracies and holds promise for application in other wave systems beyond photonics.展开更多
In addition to non-radiative guided modes, two-dimensional photonic-crystal slabs support guided resonant ones which can radiate into free space. From the polarization states of these guided resonances, a polarization...In addition to non-radiative guided modes, two-dimensional photonic-crystal slabs support guided resonant ones which can radiate into free space. From the polarization states of these guided resonances, a polarization field on a photonic band can be constructed in momentum space. Momentum-space polarization fields display complicated configurations and patterns with different types of polarization singularities inside, shedding new light on the manipulations of light flows.In this review, we summarize the recent research progress on momentum-space polarization fields and singularities in two-dimensional photonic-crystal slabs, focusing on their unique optical properties and potential applications as well.展开更多
Polarization singularities in the near-field of Gaussian vortex beams diffracted by a circular aperture are studied by a rigorous electromagnetic theory. It is shown that there exist C-points and L-lines, which depend...Polarization singularities in the near-field of Gaussian vortex beams diffracted by a circular aperture are studied by a rigorous electromagnetic theory. It is shown that there exist C-points and L-lines, which depend on off-axis displacement parameters along the x and y directions, waist width, wavelength, and topological charge of the diffracted Gaussian vortex beam, as well as on propagation distance. The results are illustrated by numerical calculations.展开更多
The evolution of polarization singularities supported in a one-dimensional periodic plasmonic system is studied.The lateral inversion symmetry of the system,which breaks the in-plane inversion symmetry and up-down mir...The evolution of polarization singularities supported in a one-dimensional periodic plasmonic system is studied.The lateral inversion symmetry of the system,which breaks the in-plane inversion symmetry and up-down mirror symmetry simultaneously,yields abundant polarization states.A complete evolution process with geometry for the polarization states is traced.In the evolution,circularly polarized points(C points)can stem from 3 different processes.In addition to the previously reported processes occurring in an isolated band,a new type of C point appearing in two bands simultaneously due to the avoided band crossing,is observed.Unlike the dielectric system with a similar structure which only supports at-Γbound states in the continuum(BICs),accidental BICs off theΓpoint are realized in this plasmonic system.This work provides a new scheme of polarization manipulation for the plasmonic systems.展开更多
Singularities are the positions at which a physical quantity becomes not well-behaved or undefined.In the context of optics,singularities can manifest in various forms,including amplitude,phase,and polarization singul...Singularities are the positions at which a physical quantity becomes not well-behaved or undefined.In the context of optics,singularities can manifest in various forms,including amplitude,phase,and polarization singularities.Among these,polarization singularities are typically classified into V-points,C-points,and L-lines.展开更多
Links and knots are exotic topological structures that have garnered significant interest across multiple branches of natural sciences.Coherent links and knots,such as those constructed by phase or polarization singul...Links and knots are exotic topological structures that have garnered significant interest across multiple branches of natural sciences.Coherent links and knots,such as those constructed by phase or polarization singularities of coherent light,have been observed in various three-dimensional optical settings.However,incoherent links and knots—knotted or connected lines of coherence singularities—arise from a fundamentally different concept.They are"hidden"in the statistic properties of a randomly fluctuating field,making their presence often elusive or undetectable.Here,we theoretically construct and experimentally demonstrate such topological entities of incoherent light.By leveraging a state-of-the-art incoherent modal-decomposition scheme,we unveil incoherent topological structures from fluctuating light speckles,including Hopf links and Trefoil knots of coherence singularities that are robust against coherence and intensity fluctuations.Our work is applicable to diverse wave systems where incoherence or practical coherence is prevalent,and may pave the way for design and implementation of statistically-shaped topological structures for various applications such as high-dimensional optical information encoding and optical communications.展开更多
Research aboutsingularities has been driving scientific advancements across mathematics and physics.Comprehending and harnessing the novel properties of singularities in photonics can facilitate the development of int...Research aboutsingularities has been driving scientific advancements across mathematics and physics.Comprehending and harnessing the novel properties of singularities in photonics can facilitate the development of integrated micro-nano devices in diverse platforms.Herein,we provide a comprehensive overview of photonic singularities emerging in structured lightfields and metamaterial structures.We classify them into several representative types:real-space singularities,momentum-space singularities,and parameter-space singularities,with discussions of their intriguing topological and dynamical properties.Moreover,we report on the latest applications of photonic singularities in broad areas,ranging from light routing,lasing,sensing,and optical manipulation to imaging and display.This review connects the singularity phenomena in different photonic systems,bridging the abstract concepts with emerging practical applications.It underscores the significance of photonic singularities in both fundamental science and various on-chip applications.展开更多
Orbital angular momentum(OAM), as a fundamental parameter of a photon, has attracted great attention in recent years. Although various properties and applications have been developed by modulating the OAM of photons, ...Orbital angular momentum(OAM), as a fundamental parameter of a photon, has attracted great attention in recent years. Although various properties and applications have been developed by modulating the OAM of photons, there is rare research about the non-uniform OAM. We propose and generate a new kind of continuously tunable azimuthally non-uniform OAM for the first time, to the best of our knowledge, which is carried by a hybridly polarized vector optical field with a cylindrically symmetric intensity profile and a complex polarization singularity. We also present the perfect vector optical field carrying non-uniform OAM with a fixed radius independent of topological charges, which can propagate steadily without radial separation, solving the problem of the unsteady propagation due to the broadened OAM spectrum of the non-uniform OAM. This new kind of tunable non-uniform OAM with a cylindrical symmetric intensity profile, complex polarization singularity, and propagation stability enriches the family of OAMs and can be widely used in many regions such as optical manipulation, quantum optics, and optical communications.展开更多
The traditional method for computing the mean displacement in latitude-longitude coordinates is a spherical meridional-zonal resultant displacement method （MRDM）, which regards the displacement as the resultant vect...The traditional method for computing the mean displacement in latitude-longitude coordinates is a spherical meridional-zonal resultant displacement method （MRDM）, which regards the displacement as the resultant vector of the meridional and zonal displacement components. However, there are inhomogeneity and singularity in the computation error of the MRDM, especially at high latitudes. Using the NCEP/NCAR long-term monthly mean wind and idealized wind fields, the inhomogeneity in the MRDM was accessed by using a great circle displacement computing method （GCDM） for non-iterative cases. The MRDM and GCDM were also compared for iteration cases by taking the trajectories from a three-time level reference method as the real trajectories. In the horizontal direction, the GCDM assumes that an air particle moves along its locating great circle and that the magnitude of the displacement equals the arc length of the great circle. The inhomogeneity of the MRDM is evaluated in terms of the horizontal dis- tance error from the products of wind speed, lapse time, and angle difference from the GCDM displacement orient. The non-iterative results show that the mean horizontal displacement computed through the MRDM has both compu- tational and analytical errors. The displacement error of the MRDM depends on the wind speed, wind direction, and the departure latitude of the air particle. It increases with the wind speed and the departure latitude. The displacement magnitude error has a four-wave pattern and the displacement direction error has a two-wave feature in the definition range of the wind direction. The iterative result shows that the displacement magnitude error and angle error of the MRDM and GCDM with respect to the reference method increase with the lapse time and have similar distribution patterns. The mean magnitude error and the angle error of the MRDM are nearly twice as large as those of the GCDM.展开更多
基金supported by the National Natural Science Foundation of China(Nos.11974259 and 12274241)。
文摘Polarization singularities beyond the bound states in the continuums(BICs)have garnered significant interest due to their potential for light manipulation.The conservation of topological charge has proven crucial in various photonic systems,and it guides the behavior of these singularities,including the generation and annihilation of BICs.This work theoretically reveals the simultaneous generation of two distinct polarization singularity types,which include off-Γaccidental BICs and Dirac-type band degeneracy points.The generation is driven by a quadratic degeneracy of symmetry-protected BICs in a photonic crystal slab.It should be noted that this is achieved through continuously tuning a geometric parameter without breaking symmetry.Importantly,the generation of both singularity types can be explained by the topological charge conservation law.This adherence ensures the stability of these singularities and allows for continuous tuning of their positions in momentum space by continuously tuning a geometric parameter while preserving symmetry.This study presents a novel framework for synthesizing and manipulating complex polarization states by combining polarization singularities from both BICs and band degeneracies and holds promise for application in other wave systems beyond photonics.
基金supported by the National Natural Science Foundation of China(Grant Nos.11727811 and 91963212)the National Key Basic Research Program of China(Grant No.2018YFA0306201)Science and Technology Commission of Shanghai Municipality(Grant Nos.19XD1434600,2019SHZDZX01,19DZ2253000,and 20501110500)。
文摘In addition to non-radiative guided modes, two-dimensional photonic-crystal slabs support guided resonant ones which can radiate into free space. From the polarization states of these guided resonances, a polarization field on a photonic band can be constructed in momentum space. Momentum-space polarization fields display complicated configurations and patterns with different types of polarization singularities inside, shedding new light on the manipulations of light flows.In this review, we summarize the recent research progress on momentum-space polarization fields and singularities in two-dimensional photonic-crystal slabs, focusing on their unique optical properties and potential applications as well.
基金Project supported by the China Postdoctoral Science Foundation (Grant No. 2009450159)the Foundation of the State Key Laboratory of Optical Technologies for Micro-Frabrication and Micro-Engineering,Chinese Academy of Sciences (Grant No. KF001)
文摘Polarization singularities in the near-field of Gaussian vortex beams diffracted by a circular aperture are studied by a rigorous electromagnetic theory. It is shown that there exist C-points and L-lines, which depend on off-axis displacement parameters along the x and y directions, waist width, wavelength, and topological charge of the diffracted Gaussian vortex beam, as well as on propagation distance. The results are illustrated by numerical calculations.
基金Project supported by the National Natural Science Foundation of China (Grant Nos.12074049 and 12047564)the Fundamental Research Funds for the Central Universities,China (Grant Nos.2020CDJQY-Z006 and 2020CDJQYZ003)the Research Foundation of SWUST (Grant No.21zx7141)。
文摘The evolution of polarization singularities supported in a one-dimensional periodic plasmonic system is studied.The lateral inversion symmetry of the system,which breaks the in-plane inversion symmetry and up-down mirror symmetry simultaneously,yields abundant polarization states.A complete evolution process with geometry for the polarization states is traced.In the evolution,circularly polarized points(C points)can stem from 3 different processes.In addition to the previously reported processes occurring in an isolated band,a new type of C point appearing in two bands simultaneously due to the avoided band crossing,is observed.Unlike the dielectric system with a similar structure which only supports at-Γbound states in the continuum(BICs),accidental BICs off theΓpoint are realized in this plasmonic system.This work provides a new scheme of polarization manipulation for the plasmonic systems.
文摘Singularities are the positions at which a physical quantity becomes not well-behaved or undefined.In the context of optics,singularities can manifest in various forms,including amplitude,phase,and polarization singularities.Among these,polarization singularities are typically classified into V-points,C-points,and L-lines.
基金supported by the National Key Research and Development Program of China(No.2022YFA1404800)National Natural Science Foundation of China(No.12174280,No.12204340,No.12192254,No.92250304,No.12434012,No.W2441005)Priority Academic Program Development of Jiangsu Higher Education Institutions,and Postgraduate Research&Practice Innovation Programof Jiangsu Province(KYCX24_3287).
文摘Links and knots are exotic topological structures that have garnered significant interest across multiple branches of natural sciences.Coherent links and knots,such as those constructed by phase or polarization singularities of coherent light,have been observed in various three-dimensional optical settings.However,incoherent links and knots—knotted or connected lines of coherence singularities—arise from a fundamentally different concept.They are"hidden"in the statistic properties of a randomly fluctuating field,making their presence often elusive or undetectable.Here,we theoretically construct and experimentally demonstrate such topological entities of incoherent light.By leveraging a state-of-the-art incoherent modal-decomposition scheme,we unveil incoherent topological structures from fluctuating light speckles,including Hopf links and Trefoil knots of coherence singularities that are robust against coherence and intensity fluctuations.Our work is applicable to diverse wave systems where incoherence or practical coherence is prevalent,and may pave the way for design and implementation of statistically-shaped topological structures for various applications such as high-dimensional optical information encoding and optical communications.
基金supported by the National Program on Key Basic Research Project of China(2022YFA1404300)National Natural Science Foundation of China(No.12325411,62288101,11774162,12322416)+5 种基金The Open Research Fund of the State Key Laboratory of Transient Optics and Photonics,Chinese Academy of Sciences(SKLST202218)the Fundamental Research Funds for the Central Universities(020414380175)Postgraduate Research&Practice Innovation Program of Jiangsu Province(KYCX23_0096)Work done in Hong Kong is supported by National Natural Science Foundation of China(Grant No.62375232)University Grants Committee/Research Grants Council of the Hong Kong Special Administrative Region,China(Project No.AoE/P-502/20,CRF Project:C1015-21E,C5031-22G,GRF Project:CityU15303521,CityU11305223,and Germany/Hong Kong Joint Research Scheme:G-CityU 101/22)City University of Hong Kong(Projects Nos.9380131,9610628,7005867).
文摘Research aboutsingularities has been driving scientific advancements across mathematics and physics.Comprehending and harnessing the novel properties of singularities in photonics can facilitate the development of integrated micro-nano devices in diverse platforms.Herein,we provide a comprehensive overview of photonic singularities emerging in structured lightfields and metamaterial structures.We classify them into several representative types:real-space singularities,momentum-space singularities,and parameter-space singularities,with discussions of their intriguing topological and dynamical properties.Moreover,we report on the latest applications of photonic singularities in broad areas,ranging from light routing,lasing,sensing,and optical manipulation to imaging and display.This review connects the singularity phenomena in different photonic systems,bridging the abstract concepts with emerging practical applications.It underscores the significance of photonic singularities in both fundamental science and various on-chip applications.
基金the National Natural Science Foundation of China(Nos.11534006,11804187,11904199,11674184,and 11774183)Natural Science Foundation of Shandong Province(No.ZR2019BF006)+1 种基金Shandong Province Higher Educational Science and Technology Program(No.J18KA229)Collaborative Innovation Center of Extreme Optics.
文摘Orbital angular momentum(OAM), as a fundamental parameter of a photon, has attracted great attention in recent years. Although various properties and applications have been developed by modulating the OAM of photons, there is rare research about the non-uniform OAM. We propose and generate a new kind of continuously tunable azimuthally non-uniform OAM for the first time, to the best of our knowledge, which is carried by a hybridly polarized vector optical field with a cylindrically symmetric intensity profile and a complex polarization singularity. We also present the perfect vector optical field carrying non-uniform OAM with a fixed radius independent of topological charges, which can propagate steadily without radial separation, solving the problem of the unsteady propagation due to the broadened OAM spectrum of the non-uniform OAM. This new kind of tunable non-uniform OAM with a cylindrical symmetric intensity profile, complex polarization singularity, and propagation stability enriches the family of OAMs and can be widely used in many regions such as optical manipulation, quantum optics, and optical communications.
基金Supported by the National Natural Science Foundation of China(41375049,41275099,41475070,and 40905021)China Postdoctoral Science Fund(2011M500894)+2 种基金Jiangsu Province Natural Science Fund(BK20131431)Natural Science Research Project of Jiangsu Province(12KJB170007)China Meteorological Administration Special Public Welfare Research Fund(GYHY201206005)
文摘The traditional method for computing the mean displacement in latitude-longitude coordinates is a spherical meridional-zonal resultant displacement method （MRDM）, which regards the displacement as the resultant vector of the meridional and zonal displacement components. However, there are inhomogeneity and singularity in the computation error of the MRDM, especially at high latitudes. Using the NCEP/NCAR long-term monthly mean wind and idealized wind fields, the inhomogeneity in the MRDM was accessed by using a great circle displacement computing method （GCDM） for non-iterative cases. The MRDM and GCDM were also compared for iteration cases by taking the trajectories from a three-time level reference method as the real trajectories. In the horizontal direction, the GCDM assumes that an air particle moves along its locating great circle and that the magnitude of the displacement equals the arc length of the great circle. The inhomogeneity of the MRDM is evaluated in terms of the horizontal dis- tance error from the products of wind speed, lapse time, and angle difference from the GCDM displacement orient. The non-iterative results show that the mean horizontal displacement computed through the MRDM has both compu- tational and analytical errors. The displacement error of the MRDM depends on the wind speed, wind direction, and the departure latitude of the air particle. It increases with the wind speed and the departure latitude. The displacement magnitude error has a four-wave pattern and the displacement direction error has a two-wave feature in the definition range of the wind direction. The iterative result shows that the displacement magnitude error and angle error of the MRDM and GCDM with respect to the reference method increase with the lapse time and have similar distribution patterns. The mean magnitude error and the angle error of the MRDM are nearly twice as large as those of the GCDM.
