Optical singularities are topological defects of electromagnetic fields;they include phase singularity in scalar fields,polarization singularity in vector fields,and three-dimensional(3D)singularities such as optical ...Optical singularities are topological defects of electromagnetic fields;they include phase singularity in scalar fields,polarization singularity in vector fields,and three-dimensional(3D)singularities such as optical skyrmions.The exploitation of photonic microstructures to generate and manipulate optical singularities has attracted wide research interest in recent years,with many photonic microstructures having been devised to this end.Accompanying these designs,scattered phenomenological theories have been proposed to expound the working mechanisms behind individual designs.In this work,instead of focusing on a specific type of microstructure,we concentrate on the most common geometric features of these microstructures—namely,symmetries—and revisit the process of generating optical singularities in microstructures from a symmetry viewpoint.By systematically employing the projection operator technique in group theory,we develop a widely applicable theoretical scheme to explore optical singularities in microstructures with rosette(i.e.,rotational and reflection)symmetries.Our scheme agrees well with previously reported works and further reveals that the eigenmodes of a symmetric microstructure can support multiplexed phase singularities in different components,such as out-of-plane,radial,azimuthal,and left-and right-handed circular components.Based on these phase singularities,more complicated optical singularities may be synthesized,including C points,V points,L lines,Néel-and bubble-type optical skyrmions,and optical lattices,to name a few.We demonstrate that the topological invariants associated with optical singularities are protected by the symmetries of the microstructure.Lastly,based on symmetry arguments,we formulate a so-called symmetry matching condition to clarify the excitation of a specific type of optical singularity.Our work establishes a unified theoretical framework to explore optical singularities in photonic microstructures with symmetries,shedding light on the symmetry origin of multidimensional and multiplexed optical singularities and providing a symmetry perspective for exploring many singularity-related effects in optics and photonics.展开更多
By using the generalized Debye diffraction integral, this paper studies the spatial correlation properties and phase singularity annihilation of apertured Gaussian Schell-model （GSM） beams in the focal region. It is...By using the generalized Debye diffraction integral, this paper studies the spatial correlation properties and phase singularity annihilation of apertured Gaussian Schell-model （GSM） beams in the focal region. It is shown that the width of the spectral degree of coherence can be larger, less than or equal to the corresponding width of spectral density, which depends not only on the scalar coherence length of the beams, but also on the truncation parameter. With a gradual increase of the truncation parameter, a pair of phase singularities of the spectral degree of coherence in the focal plane approaches each other, resulting in subwavelength structures. Finally, the annihilation of pairs of phase singularities takes place at a certain value of the truncation parameter. With increasing scalar coherence length, the annihilation occurs at the larger truncation parameter. However, the creation process of phase singularities outside the focal plane is not found for GSM beams.展开更多
In this paper, the relation between the spectral degree of coherence and degree of polarization of random electromagnetic beams is derived by the Stokes parameters. And the concept of polarization singularity is exten...In this paper, the relation between the spectral degree of coherence and degree of polarization of random electromagnetic beams is derived by the Stokes parameters. And the concept of polarization singularity is extended from spatially fully coherent beams to partially coherent electromagnetic beams. Theoretical analysis shows that correlation vortices are linearly polarized singularities. The results are illustrated by numerical examples.展开更多
This paper provides a comprehensive study of the polarization transition of reflected C-point singularities.The reflection of star-and lemon-type C-point paraxial vector beams at an air-dielectric interface is investi...This paper provides a comprehensive study of the polarization transition of reflected C-point singularities.The reflection of star-and lemon-type C-point paraxial vector beams at an air-dielectric interface is investigated.For small oblique incidences,a topological phase transition is observed exclusively in spin-maintained modes,manifesting as a shift from a vortex phase to a spin phase.Notably,as the incident angle ranges from 0 to 90 degrees,another topological phase transition occurs,the total spin components of the reflected field undergoing an interchange of topological charges(TCs),resulting in a type transition of the C-point from the star(lemon)-type to the lemon(star)-type.Furthermore,the concurrence of the C-point beam throughout the reflection process can be modulated by the incident angle,spanning almost the entire spectrum from 0 to 1.The longitudinal and transverse displacements of each spin component as well as the overall beam shifts of the reflected beam are further analyzed,revealing their dependence on the incident beam's TC combination.These findings offer novel physical insights into polarization singularity-matter interactions,holding promise for advancing research in singular optics and its applications.展开更多
Based on the propagation law of cross-spectral density function, studied in this paper are the coherence vortices of partially coherent, quasi-monochromatic singular beams with Gaussian envelope and Schell-model corre...Based on the propagation law of cross-spectral density function, studied in this paper are the coherence vortices of partially coherent, quasi-monochromatic singular beams with Gaussian envelope and Schell-model correlator in the far field, where our main attention is paid to the evolution of far-field coherence vortices into intensity vortices of fully coherent beams. The results show that, although there are usually no zeros of intensity in partially coherent beams with Gaussian envelope and Schell-model correlator~ zeros of spectral degree of coherence exist. The coherence vortices of spectral degree of coherence depend on the relative coherence length, mode index and positions of pairs of points. If a point and mode index are kept fixed, the position of coherence vortices changes with the increase of the relative coherence length. For the low coherent case there is a circular phase dislocation. In the coherent limit coherence vortices become intensity vortices of fully coherent Laguerre-Gaussian beams.展开更多
Polarization singularities,which emerge from the incoherent superposition of two vector electric fields with the same frequency,and their evolution in free space are studied analytically and illustrated by numerical e...Polarization singularities,which emerge from the incoherent superposition of two vector electric fields with the same frequency,and their evolution in free space are studied analytically and illustrated by numerical examples.It is shown that there exist C-points,L-lines,in particular,C-lines in incoherently superimposed two-dimensional wavefields.Usually,the C-lines are unstable and disappear during the free-space propagation.The motion,pair creation-annihilation process of the emergent C-points,as well as the distortion of the L-lines may take place,and the degree of polarization of the emergent C-points varies upon propagation and may be less than 1.展开更多
In this work, an all-fiber-based mode converter for generating orbital angular momentum （OAM） beams is proposed and numerically investigated. Its structure is constructed by cascading a mode selective coupler （MSC...In this work, an all-fiber-based mode converter for generating orbital angular momentum （OAM） beams is proposed and numerically investigated. Its structure is constructed by cascading a mode selective coupler （MSC） and an inner elliptical cladding fiber （IECF）. OAM modes refer to a combination of two orthogonal LPlm modes with a phase difference of ±π/2. By adjusting the parameters and controlling the splicing angle of MSC and IECF appropriately, higher-order OAM modes with topological charges of l = ±1, ±2, ±3 can be obtained with the injection of the fundamental mode LP01, resulting in a mode-conversion efficiency of almost 100%. This achievement may pave the way towards the realization of a compact, all-fiber, and high-efficiency device for increasing the transmission capacity and spectral efficiency in optical communication systems with OAM mode multiplexing.展开更多
This paper derives and uses the recurrence expressions for the power spectra of diffracted pulsed Hermite-Gaussian （HG） beams in dispersive media to study the spectral anomalies of pulsed HG beams in the far field. ...This paper derives and uses the recurrence expressions for the power spectra of diffracted pulsed Hermite-Gaussian （HG） beams in dispersive media to study the spectral anomalies of pulsed HG beams in the far field. Numerical results are given to illustrate the dependence of spectral switches on the pulse parameters, truncation parameter and dispersive property of the medium. The potential application of spectral anomalies of ultrashort pulsed beams in information encoding and transmission is discussed.展开更多
We provide the first report on the harmonics generated by an intense femtosecond vector beam that ~s normally mcment on a solid target. By using 2D particle-in-cell （PIC） codes, we observe the third and the fifth ha...We provide the first report on the harmonics generated by an intense femtosecond vector beam that ~s normally mcment on a solid target. By using 2D particle-in-cell （PIC） codes, we observe the third and the fifth harmonic signals with the same vector structure as the driving beam, and obtain an attosecond vector beam pulse train. We also show that the conversion efficiencies of the third and the fifth harmonics reach their maxima for a plasma density of four times the critical density due to the plasma resonating with the driving force. This method provides a new means of generating intense extreme ultraviolet （XUV） vector beams via ultra-intense laser-driven harmonics.展开更多
We investigate the bounded travelling wave solutions of the Biswas-Arshed model(BAM)including the low group velocity dispersion and excluding the self-phase modulation.We integrate the nonlinear structure of the model...We investigate the bounded travelling wave solutions of the Biswas-Arshed model(BAM)including the low group velocity dispersion and excluding the self-phase modulation.We integrate the nonlinear structure of the model to obtain bounded optical solitons which pass through the optical fibers in the non-Kerr media.The bifurcation technique of the dynamical system is used to achieve the parameter bifurcation sets and split the parameter space into various areaswhich correspond to different phase portraits.All bounded optical solitons and bounded periodic wave solutions are identified and derived conforming to each region of these phase portraits.We also apply the extended sinh-Gordon equation expansion and the generalized Kudryashov integral schemes to obtain additional bounded optical soliton solutions of the BAM nonlinearity.We present more bounded optical shock waves,the bright-dark solitary wave,and optical rogue waves for the structure model via these schemes in different aspects.展开更多
Perfect vector vortex beams(PVVBs)possess various degrees of freedom(Do Fs)for optical information applications,benefiting from increasing information capacity,processing speed,etc.During the last two decades,various ...Perfect vector vortex beams(PVVBs)possess various degrees of freedom(Do Fs)for optical information applications,benefiting from increasing information capacity,processing speed,etc.During the last two decades,various methods have been proposed for generating and controlling PVVBs,but most of these methods can only manipulate two or three Do Fs,greatly hindering further exploration and application of PVVBs.To overcome this problem,we propose an attenuation-controlled holographic technique based on metasurfaces,which can realize the arbitrary and independent control of 6-DoFs,greatly improving the manipulation dimension of PVVBs.The PVVBs with 6 on-demand Do Fs can appear in the array forms of either concentric or matrix rings without cross-talks or number limitations,which notably enlarges the number of information channels that can be simultaneously employed.Furthermore,we introduce a multi-dimensional dynamic addressing strategy for optical encryption with the advantages of both large capacity and high security due to its theoretically infinite code space.Our findings can not only deepen the study of optical field manipulation at the nanoscale,but also expand the application of structural light,promoting their utilization across the fields of nanophotonics,integrated optics,and optical information science at the high-dimensional level.展开更多
The spatial features of a light field, such as in the form of the optical singularities, provide a new degree of freedom for the application of light fields in different areas of science and technology. However, altho...The spatial features of a light field, such as in the form of the optical singularities, provide a new degree of freedom for the application of light fields in different areas of science and technology. However, although the exploration of structured light is growing rapidly, the investigation of strong-field photoionization using such light fields is noticeably lagging behind. Here, we present an experimental study that reveals the signatures of intense, structured light fields with controlled optical singularities in strong-field photoionization. The different types of optical singularities can be identified through photoionization observables,i.e., photoelectron momentum distributions(PMDs). By concurrently shifting the locations of the phase and polarization singularities, the focal electric field features can be designated, and subsequently, the photoionization appearances can be manipulated. In this process, the behaviors of the different intense optical singularities are clearly visualized by the PMDs. This work will advance both the strong-field science and singularity optics.展开更多
In view of wide applications of structured light fields and plasmonic vortices,we propose the concept of compound plasmonic vortex and design several structured plasmonic vortex generators.This kind of structured plas...In view of wide applications of structured light fields and plasmonic vortices,we propose the concept of compound plasmonic vortex and design several structured plasmonic vortex generators.This kind of structured plasmonic vortex generators consists of multiple spiral nanoslits and they can generate two or more concentric plasmonic vortices.Different from Laguerre-Gaussian beam,the topological charge of the plasmonic vortex in different region is different.Theoretical analysis lays the basis for the design of radially structured plasmonic vortex generators and numerical simulations for several examples confirm the effectiveness of the design principle.The discussions about the interference of vortex fields definite the generation condition for the structured vortex.This work provides a design methodology for generating new vortices using spiral nanoslits and the advanced radially structured plasmonic vortices is helpful for broadening the applications of vortex fields.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
基金supported by the National Natural Science Foun-dation of China(62301596 and 62288101)Shaanxi Provincial Science and Technology Innovation Team(23-CX-TD-48)+4 种基金the KU Leuven internal funds:the C1 Project(C14/19/083)the Interdisciplinary Network Project(IDN/20/014)the Small Infrastructure Grant(KA/20/019)the Research Foundation of Flanders(FWO)Project(G090017N,G088822N,and V408823N)the Danish National Research Foundation(DNRF165).
文摘Optical singularities are topological defects of electromagnetic fields;they include phase singularity in scalar fields,polarization singularity in vector fields,and three-dimensional(3D)singularities such as optical skyrmions.The exploitation of photonic microstructures to generate and manipulate optical singularities has attracted wide research interest in recent years,with many photonic microstructures having been devised to this end.Accompanying these designs,scattered phenomenological theories have been proposed to expound the working mechanisms behind individual designs.In this work,instead of focusing on a specific type of microstructure,we concentrate on the most common geometric features of these microstructures—namely,symmetries—and revisit the process of generating optical singularities in microstructures from a symmetry viewpoint.By systematically employing the projection operator technique in group theory,we develop a widely applicable theoretical scheme to explore optical singularities in microstructures with rosette(i.e.,rotational and reflection)symmetries.Our scheme agrees well with previously reported works and further reveals that the eigenmodes of a symmetric microstructure can support multiplexed phase singularities in different components,such as out-of-plane,radial,azimuthal,and left-and right-handed circular components.Based on these phase singularities,more complicated optical singularities may be synthesized,including C points,V points,L lines,Néel-and bubble-type optical skyrmions,and optical lattices,to name a few.We demonstrate that the topological invariants associated with optical singularities are protected by the symmetries of the microstructure.Lastly,based on symmetry arguments,we formulate a so-called symmetry matching condition to clarify the excitation of a specific type of optical singularity.Our work establishes a unified theoretical framework to explore optical singularities in photonic microstructures with symmetries,shedding light on the symmetry origin of multidimensional and multiplexed optical singularities and providing a symmetry perspective for exploring many singularity-related effects in optics and photonics.
基金supported by the National Natural Science Foundation of China (Grant No 10574097)the Youth Foundation of University of Electronics Science and Technology of China
文摘By using the generalized Debye diffraction integral, this paper studies the spatial correlation properties and phase singularity annihilation of apertured Gaussian Schell-model （GSM） beams in the focal region. It is shown that the width of the spectral degree of coherence can be larger, less than or equal to the corresponding width of spectral density, which depends not only on the scalar coherence length of the beams, but also on the truncation parameter. With a gradual increase of the truncation parameter, a pair of phase singularities of the spectral degree of coherence in the focal plane approaches each other, resulting in subwavelength structures. Finally, the annihilation of pairs of phase singularities takes place at a certain value of the truncation parameter. With increasing scalar coherence length, the annihilation occurs at the larger truncation parameter. However, the creation process of phase singularities outside the focal plane is not found for GSM beams.
基金Project support by the Open Foundation of the Sate Key Laboratory of Optical Technologies for Micro-Fabrication & Micro-Engineering,Chinese Academy of Sciences,and China Postdoctoral Science Foundation (CPSF) (Grant No. 2009450159)
文摘In this paper, the relation between the spectral degree of coherence and degree of polarization of random electromagnetic beams is derived by the Stokes parameters. And the concept of polarization singularity is extended from spatially fully coherent beams to partially coherent electromagnetic beams. Theoretical analysis shows that correlation vortices are linearly polarized singularities. The results are illustrated by numerical examples.
基金supported by the National Key Research and Development Program of China(Grant Nos.2023YFA1406903,and 2022YFA1404800)the National Natural Science Foundation of China(Grant Nos.12374307,12234009,and 12274215)。
文摘This paper provides a comprehensive study of the polarization transition of reflected C-point singularities.The reflection of star-and lemon-type C-point paraxial vector beams at an air-dielectric interface is investigated.For small oblique incidences,a topological phase transition is observed exclusively in spin-maintained modes,manifesting as a shift from a vortex phase to a spin phase.Notably,as the incident angle ranges from 0 to 90 degrees,another topological phase transition occurs,the total spin components of the reflected field undergoing an interchange of topological charges(TCs),resulting in a type transition of the C-point from the star(lemon)-type to the lemon(star)-type.Furthermore,the concurrence of the C-point beam throughout the reflection process can be modulated by the incident angle,spanning almost the entire spectrum from 0 to 1.The longitudinal and transverse displacements of each spin component as well as the overall beam shifts of the reflected beam are further analyzed,revealing their dependence on the incident beam's TC combination.These findings offer novel physical insights into polarization singularity-matter interactions,holding promise for advancing research in singular optics and its applications.
基金Project supported by the National Natural Science Foundation of China （Grant No 10574097）.
文摘Based on the propagation law of cross-spectral density function, studied in this paper are the coherence vortices of partially coherent, quasi-monochromatic singular beams with Gaussian envelope and Schell-model correlator in the far field, where our main attention is paid to the evolution of far-field coherence vortices into intensity vortices of fully coherent beams. The results show that, although there are usually no zeros of intensity in partially coherent beams with Gaussian envelope and Schell-model correlator~ zeros of spectral degree of coherence exist. The coherence vortices of spectral degree of coherence depend on the relative coherence length, mode index and positions of pairs of points. If a point and mode index are kept fixed, the position of coherence vortices changes with the increase of the relative coherence length. For the low coherent case there is a circular phase dislocation. In the coherent limit coherence vortices become intensity vortices of fully coherent Laguerre-Gaussian beams.
基金Project supported by the National Natural Science Foundation of China (Grant No. 10874125)
文摘Polarization singularities,which emerge from the incoherent superposition of two vector electric fields with the same frequency,and their evolution in free space are studied analytically and illustrated by numerical examples.It is shown that there exist C-points,L-lines,in particular,C-lines in incoherently superimposed two-dimensional wavefields.Usually,the C-lines are unstable and disappear during the free-space propagation.The motion,pair creation-annihilation process of the emergent C-points,as well as the distortion of the L-lines may take place,and the degree of polarization of the emergent C-points varies upon propagation and may be less than 1.
基金This work was supported by National Natural Science Foundation of China （Grant No. 61275049）.
文摘In this work, an all-fiber-based mode converter for generating orbital angular momentum （OAM） beams is proposed and numerically investigated. Its structure is constructed by cascading a mode selective coupler （MSC） and an inner elliptical cladding fiber （IECF）. OAM modes refer to a combination of two orthogonal LPlm modes with a phase difference of ±π/2. By adjusting the parameters and controlling the splicing angle of MSC and IECF appropriately, higher-order OAM modes with topological charges of l = ±1, ±2, ±3 can be obtained with the injection of the fundamental mode LP01, resulting in a mode-conversion efficiency of almost 100%. This achievement may pave the way towards the realization of a compact, all-fiber, and high-efficiency device for increasing the transmission capacity and spectral efficiency in optical communication systems with OAM mode multiplexing.
基金supported by the National Natural Science Foundation of China (Grant No 60678055)
文摘This paper derives and uses the recurrence expressions for the power spectra of diffracted pulsed Hermite-Gaussian （HG） beams in dispersive media to study the spectral anomalies of pulsed HG beams in the far field. Numerical results are given to illustrate the dependence of spectral switches on the pulse parameters, truncation parameter and dispersive property of the medium. The potential application of spectral anomalies of ultrashort pulsed beams in information encoding and transmission is discussed.
基金supported by the National Basic Research Program of China(Grant Nos.2013CBA01501 and 2013CBA01504)the National Key Scientific Instrument and Equipment Development Project of China(Grant No.2012YQ120047)+1 种基金Chinese Academy of Science Key Program,the National Natural Science of China(Grant Nos.11135012 and 11375262)the Project of Shandong Province Higher Educational Science and Technology Program,China(Grant No.J11LA52)
文摘We provide the first report on the harmonics generated by an intense femtosecond vector beam that ~s normally mcment on a solid target. By using 2D particle-in-cell （PIC） codes, we observe the third and the fifth harmonic signals with the same vector structure as the driving beam, and obtain an attosecond vector beam pulse train. We also show that the conversion efficiencies of the third and the fifth harmonics reach their maxima for a plasma density of four times the critical density due to the plasma resonating with the driving force. This method provides a new means of generating intense extreme ultraviolet （XUV） vector beams via ultra-intense laser-driven harmonics.
基金supported by the Deanship of ScientificResearch,Prince Sattam bin Abdulaziz University,Alkharj,Saudi Arabia,under Grant No.2021/01/19122.
文摘We investigate the bounded travelling wave solutions of the Biswas-Arshed model(BAM)including the low group velocity dispersion and excluding the self-phase modulation.We integrate the nonlinear structure of the model to obtain bounded optical solitons which pass through the optical fibers in the non-Kerr media.The bifurcation technique of the dynamical system is used to achieve the parameter bifurcation sets and split the parameter space into various areaswhich correspond to different phase portraits.All bounded optical solitons and bounded periodic wave solutions are identified and derived conforming to each region of these phase portraits.We also apply the extended sinh-Gordon equation expansion and the generalized Kudryashov integral schemes to obtain additional bounded optical soliton solutions of the BAM nonlinearity.We present more bounded optical shock waves,the bright-dark solitary wave,and optical rogue waves for the structure model via these schemes in different aspects.
基金supported by the National Key R&D Program of China(Grant No.2021YFA1400804)the National Natural Science Foundation of China(Grant Nos.12222415,and 12334017)+1 种基金the Guangdong Provincial Natural Science Fund Projects(Grant No.2024B1515040013)the Guangdong Provincial Quantum Science Strategic Initiative(Grant No.GDZX2305005)。
文摘Perfect vector vortex beams(PVVBs)possess various degrees of freedom(Do Fs)for optical information applications,benefiting from increasing information capacity,processing speed,etc.During the last two decades,various methods have been proposed for generating and controlling PVVBs,but most of these methods can only manipulate two or three Do Fs,greatly hindering further exploration and application of PVVBs.To overcome this problem,we propose an attenuation-controlled holographic technique based on metasurfaces,which can realize the arbitrary and independent control of 6-DoFs,greatly improving the manipulation dimension of PVVBs.The PVVBs with 6 on-demand Do Fs can appear in the array forms of either concentric or matrix rings without cross-talks or number limitations,which notably enlarges the number of information channels that can be simultaneously employed.Furthermore,we introduce a multi-dimensional dynamic addressing strategy for optical encryption with the advantages of both large capacity and high security due to its theoretically infinite code space.Our findings can not only deepen the study of optical field manipulation at the nanoscale,but also expand the application of structural light,promoting their utilization across the fields of nanophotonics,integrated optics,and optical information science at the high-dimensional level.
基金supported by the National Natural Science Foundation of China (Grant Nos. 92050201, 11774013, and 11527901)。
文摘The spatial features of a light field, such as in the form of the optical singularities, provide a new degree of freedom for the application of light fields in different areas of science and technology. However, although the exploration of structured light is growing rapidly, the investigation of strong-field photoionization using such light fields is noticeably lagging behind. Here, we present an experimental study that reveals the signatures of intense, structured light fields with controlled optical singularities in strong-field photoionization. The different types of optical singularities can be identified through photoionization observables,i.e., photoelectron momentum distributions(PMDs). By concurrently shifting the locations of the phase and polarization singularities, the focal electric field features can be designated, and subsequently, the photoionization appearances can be manipulated. In this process, the behaviors of the different intense optical singularities are clearly visualized by the PMDs. This work will advance both the strong-field science and singularity optics.
基金the National Natural Science Foundation of China(NSFC)(Grant Nos.10874105 and 11704231).
文摘In view of wide applications of structured light fields and plasmonic vortices,we propose the concept of compound plasmonic vortex and design several structured plasmonic vortex generators.This kind of structured plasmonic vortex generators consists of multiple spiral nanoslits and they can generate two or more concentric plasmonic vortices.Different from Laguerre-Gaussian beam,the topological charge of the plasmonic vortex in different region is different.Theoretical analysis lays the basis for the design of radially structured plasmonic vortex generators and numerical simulations for several examples confirm the effectiveness of the design principle.The discussions about the interference of vortex fields definite the generation condition for the structured vortex.This work provides a design methodology for generating new vortices using spiral nanoslits and the advanced radially structured plasmonic vortices is helpful for broadening the applications of vortex fields.
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.
