The interest in tailoring light in all its degrees of freedom is steadily gaining traction,driven by the tremendous developments in the toolkit for the creation,control and detection of what is now called structured l...The interest in tailoring light in all its degrees of freedom is steadily gaining traction,driven by the tremendous developments in the toolkit for the creation,control and detection of what is now called structured light.Because the complexity of these optical fields is generally understood in terms of interference,the tools have historically been linear optical elements that create the desired superpositions.For this reason,despite the long and impressive history of nonlinear optics,only recently has the spatial structure of light in nonlinear processes come to the fore.In this review we provide a concise theoretical framework for understanding nonlinear optics in the context of structured light,offering an overview and perspective on the progress made,and the challenges that remain.展开更多
Spatial light modulators,as dynamic flat-panel optical devices,have witnessed rapid development over the past two decades,concomitant with the advancements in micro-and opto-electronic integration technology.In partic...Spatial light modulators,as dynamic flat-panel optical devices,have witnessed rapid development over the past two decades,concomitant with the advancements in micro-and opto-electronic integration technology.In particular,liquid-crystal spatial light modulator(LC-SLM)technologies have been regarded as versatile tools for generating arbitrary optical fields and tailoring all degrees of freedom beyond just phase and amplitude.These devices have gained significant interest in the nascent field of structured light in space and time,facilitated by their ease of use and real-time light manipulation,fueling both fundamental research and practical applications.Here we provide an overview of the key working principles of LC-SLMs and review the significant progress made to date in their deployment for various applications,covering topics as diverse as beam shaping and steering,holography,optical trapping and tweezers,measurement,wavefront coding,optical vortex,and quantum optics.Finally,we conclude with an outlook on the potential opportunities and technical challenges in this rapidly developing field.展开更多
Optical metrology is a well-established subject,dating back to early interferometry techniques utilizing light's linear momentum through fringes.In recent years,significant interest has arisen in using vortex ligh...Optical metrology is a well-established subject,dating back to early interferometry techniques utilizing light's linear momentum through fringes.In recent years,significant interest has arisen in using vortex light with orbital angular momentum(OAM),where the phase twists around a singular vortex in space or time.This has expanded metrology's boundaries to encompass highly sensitive chiral interactions between light and matter,three-dimensional motion detection via linear and rotational Doppler effects,and modal approaches surpassing the resolution limit for improved profling and quantification.The intricate structure of vortex light,combined with the integration of artifcial intelligence into optical metrology,unlocks new paradigms for expanding measurement frameworks through additional degrees of freedom,offering the potential for more effcient and accurate sensing and metrological advancements.This review aims to provide a comprehensive overview of recent advances and future trends in optical metrology with structured light,specifically focusing on how utilizing vortex beams has revolutionized metrology and remote sensing,transitioning from classical to quantum approaches.展开更多
We are at an inflection point in our control of light,beyond 2D transverse intensity patterns and towards tailored light in space and time,for complete 4D control.When new degrees of freedom are added to the mix,the p...We are at an inflection point in our control of light,beyond 2D transverse intensity patterns and towards tailored light in space and time,for complete 4D control.When new degrees of freedom are added to the mix,the potential is enormous.It is novel spatiotemporal optical wavepackets that are lighting the way to this exciting future.Controlling light can be traced back thousands of years,with stories of directing sunlight from mirrors to burn attacking ships,an early form of incoherent light shaping[1].In this example,when light is added to light,the outcome is proportionally more light.This paradigm is broken when the light can be treated as coherent waves:light added to light can result in darkness.Thomas Young did exactly this to create spatial intensity structure in the form of“fringes”.Moving beyond just two displaced splits,his notion of fringes can be generalized to any geometry and any degree of freedom[2].His experiment revealed just how easy it is to control the spatial structure of light by simply adding plane waves,initially in the transverse plane for 2D structured light in intensity,but now in more abstract degrees of freedom of light[3].展开更多
Structured light carrying angular momentum,such as spin angular momentum(SAM)and orbital angular momentum(OAM),has been at the core of new science and applications,driving the need for compact on-chip sources.While ma...Structured light carrying angular momentum,such as spin angular momentum(SAM)and orbital angular momentum(OAM),has been at the core of new science and applications,driving the need for compact on-chip sources.While many static on-chip solutions have been demonstrated,as well as on-chip sources of free-space modes,no architecture that is fully reconfigurable in all angular momentum states and all on-chip has so far been possible.Here we report the first all-on-chip structured light generator for the creation of both scalar and vectorial angular momentum beams,facilitated through a silicon-on-insulator(SOI)chip with a silica mode multiplexer(silica chip).We selectively stimulate six linearly-polarized(LP)modes of the silica multimode bus waveguide,precisely controlling the modal powers and phases with the SOI chip.This allows us to tailor arbitrary superpositions of the mode set thus synthesizing common cylindrical vector vortex beams as well as OAM beams of controlled spin and topological charge.Our compact structured light generator exhibits high switching speed and operates across the telecom band,paving the way for applications such as optical communication and integrated quantum technologies.展开更多
Atmospheric turbulence degrades the performance of free-space optical(FSO)communication and remote sensing systems by introducing phase and intensity distortions.While a majority of research focuses on mitigating thes...Atmospheric turbulence degrades the performance of free-space optical(FSO)communication and remote sensing systems by introducing phase and intensity distortions.While a majority of research focuses on mitigating these effects to ensure robust signal transmission,an underexplored alternative is to leverage the transformation of structured light to characterize the turbulent medium itself.Here,we introduce a deep learning framework that fuses post-propagation intensity speckle patterns and orbital angular momentum(OAM)spectral data for atmospheric turbulence parameter inference.Our architecture,based on a modified InceptionNet backbone,is optimized to extract and integrate multi-scale features from these distinct optical modalities.This multimodal approach achieves validation accuracies exceeding 80%,substantially outperforming conventional single-modality baselines.The framework demonstrates high inference accuracy and enhanced training stability across a broad range of simulated turbulent conditions,quantified by varying Fried parameters(r_(0))and Reynolds numbers(Re).This work presents a scalable and data-efficient method for turbulence characterization,offering a pathway toward robust environmental sensing and the optimization of dynamic FSO systems.展开更多
Topology is usually perceived intrinsically immutable for a given object.We argue that optical topologies do not immediately enjoy such benefits.Using'optical skyrmions'as an example,we show that they will exh...Topology is usually perceived intrinsically immutable for a given object.We argue that optical topologies do not immediately enjoy such benefits.Using'optical skyrmions'as an example,we show that they will exhibit varying textures and topological invariants(skyrmion numbers),depending on how to construct the skyrmion vector when projecting from real to parameter space.We demonstrate the fragility of optical skyrmions under a ubiquitous scenario-simple reflection off an optical mirror.Optical topology is not without benefit,but it must not be assumed.展开更多
Structured light refers to the arbitrarily tailoring of optical fields in all their degrees of freedom(DoFs),from spatial to temporal.Although orbital angular momentum(OAM)is perhaps the most topical example,and celeb...Structured light refers to the arbitrarily tailoring of optical fields in all their degrees of freedom(DoFs),from spatial to temporal.Although orbital angular momentum(OAM)is perhaps the most topical example,and celebrating 30 years since its connection to the spatial structure of light,control over other DoFs is slowly gaining traction,promising access to higher-dimensional forms of structured light.Nevertheless,harnessing these new DoFs in quantum and classical states remains challenging,with the toolkit still in its infancy.In this perspective,we discuss methods,challenges,and opportunities for the creation,detection,and control of multiple DoFs for higher-dimensional structured light.We present a roadmap for future development trends,from fundamental research to applications,concentrating on the potential for larger-capacity,higher-security information processing and communication,and beyond.展开更多
Structured light is routinely used in free-space optical communication channels,both classical and quantum,where information is encoded in the spatial structure of the mode for increased bandwidth.Both real-world and ...Structured light is routinely used in free-space optical communication channels,both classical and quantum,where information is encoded in the spatial structure of the mode for increased bandwidth.Both real-world and experimentally simulated turbulence conditions have revealed that free-space structured light modes are perturbed in some manner by turbulence,resulting in both amplitude and phase distortions,and consequently,much attention has focused on whether one mode type is more robust than another,but with seemingly inconclusive and contradictory results.We present complex forms of structured light that are invariant under propagation through the atmosphere:the true eigenmodes of atmospheric turbulence.We provide a theoretical procedure for obtaining these eigenmodes and confirm their invariance both numerically and experimentally.Although we have demonstrated the approach on atmospheric turbulence,its generality allows it to be extended to other channels too,such as aberrated paths,underwater,and in optical fiber.展开更多
It is well known that the entanglement of a quantum state is invariant under local unitary transformations.This rule dictates,for example,that the entanglement of internal degrees of freedom of a photon remains invari...It is well known that the entanglement of a quantum state is invariant under local unitary transformations.This rule dictates,for example,that the entanglement of internal degrees of freedom of a photon remains invariant during free-space propagation.Here,we outline a scenario in which this paradigm does not hold.Using local Bell states engineered from classical vector vortex beams with non-separable degrees of freedom,the so-called classically entangled states,we demonstrate that the entanglement evolves during propagation,oscillating between maximally entangled(purely vector)and product states(purely scalar).We outline the spin–orbit interaction behind these novel propagation dynamics and confirm the results experimentally,demonstrating spin–orbit coupling in paraxial beams.This demonstration highlights a hitherto unnoticed property of classical entanglement and simultaneously offers a device for the on-demand delivery of vector states to targets,for example,for dynamic laser materials processing,switchable resolution within stimulated emission depletion(STED)systems,and a tractor beam for entanglement.展开更多
Vector beams,non-separable in spatial mode and polarisation,have emerged as enabling tools in many diverse applications,from communication to imaging.This applicability has been achieved by sophisticated laser designs...Vector beams,non-separable in spatial mode and polarisation,have emerged as enabling tools in many diverse applications,from communication to imaging.This applicability has been achieved by sophisticated laser designs controlling the spin and orbital angular momentum,but so far is restricted to only two-dimensional states.Here we demonstrate the first vectorially structured light created and fully controlled in eight dimensions,a new state-of-the-art.We externally modulate our beam to control,for the frst time,the complete set of classical Greenberger-Horne-Zeilinger(GHZ)states in paraxial structured light beams,in analogy with high-dimensional multi-partite quantum entangled states,and introduce a new tomography method to verify their fidelity.Our complete theoretical framework reveals a rich parameter space for further extending the dimensionality and degrees of freedom,opening new pathways for vetorilly structured light in the classical and quantum regimes.展开更多
A well-known defect introduced during the fabrication of GRIN lenses can be exploited for the creation,detection and wave-guiding of exotic forms of vectorial structured light,bringing the toolkit into the realm of co...A well-known defect introduced during the fabrication of GRIN lenses can be exploited for the creation,detection and wave-guiding of exotic forms of vectorial structured light,bringing the toolkit into the realm of common laboratory optics.展开更多
Structured light,where complex optical fields are tailored in all their degrees of freedom,has become highly topical of late,advanced by a sophisticated toolkit comprising both linear and nonlinear optics.Removing und...Structured light,where complex optical fields are tailored in all their degrees of freedom,has become highly topical of late,advanced by a sophisticated toolkit comprising both linear and nonlinear optics.Removing undesired structure from light is far less developed,leveraging mostly on inverting the distortion,e.g.,with adaptive optics or the inverse transmission matrix of a complex channel,both requiring that the distortion be fully characterized through appropriate measurement.We show that distortions in spatially structured light can be corrected through difference-frequency generation in a nonlinear crystal without any need for the distortion to be known.We demonstrate the versatility of our approach using a wide range of aberrations and structured light modes,including higher-order orbital angular momentum(OAM)beams,showing excellent recovery of the original undistorted field.To highlight the efficacy of this process,we deploy the system in a prepare-and-measure communications link with OAM,showing minimal cross talk even when the transmission channel is highly aberrated,and outline how the approach could be extended to alternative experimental modalities and nonlinear processes.Our demonstration of light-correcting light without the need for measurement opens an approach to measurement-free error correction for classical and quantum structured light,with direct applications in imaging,sensing,and communication.展开更多
One of the most prominent features of quantum entanglement is its invariability under local unitary transformations,which implies that the degree of entanglement or nonseparability remains constant during free-space p...One of the most prominent features of quantum entanglement is its invariability under local unitary transformations,which implies that the degree of entanglement or nonseparability remains constant during free-space propagation,true for both quantum and classically entangled modes.Here we demonstrate an exception to this rule using a carefully engineered vectorial light field,and we study its nonseparability dynamics upon free-space propagation.We show that the local nonseparability between the spatial and polarization degrees of freedom dramatically decays to zero while preserving the purity of the state and hence the global nonseparability.We show this by numerical simulations and corroborate it experimentally.Our results evince novel properties of classically entangled modes and point to the need for new measures of nonseparability for such vectorial fields,while paving the way for novel applications for customized structured light.展开更多
Orbital angular momentum interactions at the nanoscale have remained elusive because the phase structure becomes unresolved.Now researchers have shown how to overcome this with tightly focused beams,demonstrating a re...Orbital angular momentum interactions at the nanoscale have remained elusive because the phase structure becomes unresolved.Now researchers have shown how to overcome this with tightly focused beams,demonstrating a recordhigh six-dimensional encoding in an ultra-dense nanoscale volume.展开更多
Controlling light in all its degrees of freedom is steadily gaining traction,extending our familiar 2D transverse forms of electromagnetic waves to include 3D control(all three components of the electric field),and sp...Controlling light in all its degrees of freedom is steadily gaining traction,extending our familiar 2D transverse forms of electromagnetic waves to include 3D control(all three components of the electric field),and spatiotemporal control for 4D forms of structured light.1 Despite the advances,there still exist solutions to Maxwell’s equations that have not yet been demonstrated,2 hindered by the need to induce higherorder multipoles(beyond dipoles)and toroidal excitations in matter.3 Reporting in Nature Photonics,Qiwen Zhan and colleagues demonstrate the first optical toroidal vortex.4 They bypass the need for exotic materials and rare electronic transitions by exploiting conformal mapping of a space–time shaped vortex pulse,twisting and folding the optical field to form the familiar toroidal nature.Their approach heralds new spatial and temporal control of structured light,with the potential to impact fields from topology to quantum information.展开更多
Recently there is an increasing interest in tailored optical fields with complex amplitude, phase and polarization spatial distributions, as well as specifically designed temporal waveforms. Scalar optical vortices ca...Recently there is an increasing interest in tailored optical fields with complex amplitude, phase and polarization spatial distributions, as well as specifically designed temporal waveforms. Scalar optical vortices carrying orbital angular momentum and vectorial vortices such as radially and azimuthally polarized beams are among the most intensively studied examples.展开更多
Nano-structured metasurfaces have to be tailored from artificial atoms that act as toroidal emitters,giving rise to a new form of light long predicted:"flying doughnuts"as propagating spatial-temporal electr...Nano-structured metasurfaces have to be tailored from artificial atoms that act as toroidal emitters,giving rise to a new form of light long predicted:"flying doughnuts"as propagating spatial-temporal electromagnetic toroidal pulses in both the visible and THz regimes.展开更多
High-dimensional quantum states are known to offer advantages over their two-dimensional qubit counterparts,but their preparation and manipulation has been bulky and cumbersome.Now,quantum state control has been demon...High-dimensional quantum states are known to offer advantages over their two-dimensional qubit counterparts,but their preparation and manipulation has been bulky and cumbersome.Now,quantum state control has been demonstrated on-chip with a~1μm2 footprint and nm-scale features,producing up to eight-dimensional quantum states and ushering in a new route to large quantum information encoding on a small footprint.展开更多
Transparent objects are invisible to traditional cameras because they can only detect intensity fluctuations,necessitating the need for interferometry followed by computationally intensive digital image processing.Now...Transparent objects are invisible to traditional cameras because they can only detect intensity fluctuations,necessitating the need for interferometry followed by computationally intensive digital image processing.Now it is shown that the necessary transformations can be performed optically by combining machine learning and diffractive optics,for a direct in-situ measurement of transparent objects with conventional cameras.展开更多
文摘The interest in tailoring light in all its degrees of freedom is steadily gaining traction,driven by the tremendous developments in the toolkit for the creation,control and detection of what is now called structured light.Because the complexity of these optical fields is generally understood in terms of interference,the tools have historically been linear optical elements that create the desired superpositions.For this reason,despite the long and impressive history of nonlinear optics,only recently has the spatial structure of light in nonlinear processes come to the fore.In this review we provide a concise theoretical framework for understanding nonlinear optics in the context of structured light,offering an overview and perspective on the progress made,and the challenges that remain.
基金supports from National Natural Science Foundation of China (No.62235009).
文摘Spatial light modulators,as dynamic flat-panel optical devices,have witnessed rapid development over the past two decades,concomitant with the advancements in micro-and opto-electronic integration technology.In particular,liquid-crystal spatial light modulator(LC-SLM)technologies have been regarded as versatile tools for generating arbitrary optical fields and tailoring all degrees of freedom beyond just phase and amplitude.These devices have gained significant interest in the nascent field of structured light in space and time,facilitated by their ease of use and real-time light manipulation,fueling both fundamental research and practical applications.Here we provide an overview of the key working principles of LC-SLMs and review the significant progress made to date in their deployment for various applications,covering topics as diverse as beam shaping and steering,holography,optical trapping and tweezers,measurement,wavefront coding,optical vortex,and quantum optics.Finally,we conclude with an outlook on the potential opportunities and technical challenges in this rapidly developing field.
基金support from the 111 Project(B17035)National Natural Science Foundation of China(Grant no.U20B2059,62231021,61621005,62201613)+2 种基金Shanghai Aerospace Science and Technology Innovation support from the 111 Project(B17035)National Natural Science Foundation of China(Grant no.U20B2059,62231021,61621005,62201613)Shanghai Aerospace Science and Technology Innovation Foundation(SAST-2022-069)。
文摘Optical metrology is a well-established subject,dating back to early interferometry techniques utilizing light's linear momentum through fringes.In recent years,significant interest has arisen in using vortex light with orbital angular momentum(OAM),where the phase twists around a singular vortex in space or time.This has expanded metrology's boundaries to encompass highly sensitive chiral interactions between light and matter,three-dimensional motion detection via linear and rotational Doppler effects,and modal approaches surpassing the resolution limit for improved profling and quantification.The intricate structure of vortex light,combined with the integration of artifcial intelligence into optical metrology,unlocks new paradigms for expanding measurement frameworks through additional degrees of freedom,offering the potential for more effcient and accurate sensing and metrological advancements.This review aims to provide a comprehensive overview of recent advances and future trends in optical metrology with structured light,specifically focusing on how utilizing vortex beams has revolutionized metrology and remote sensing,transitioning from classical to quantum approaches.
文摘We are at an inflection point in our control of light,beyond 2D transverse intensity patterns and towards tailored light in space and time,for complete 4D control.When new degrees of freedom are added to the mix,the potential is enormous.It is novel spatiotemporal optical wavepackets that are lighting the way to this exciting future.Controlling light can be traced back thousands of years,with stories of directing sunlight from mirrors to burn attacking ships,an early form of incoherent light shaping[1].In this example,when light is added to light,the outcome is proportionally more light.This paradigm is broken when the light can be treated as coherent waves:light added to light can result in darkness.Thomas Young did exactly this to create spatial intensity structure in the form of“fringes”.Moving beyond just two displaced splits,his notion of fringes can be generalized to any geometry and any degree of freedom[2].His experiment revealed just how easy it is to control the spatial structure of light by simply adding plane waves,initially in the transverse plane for 2D structured light in intensity,but now in more abstract degrees of freedom of light[3].
基金supported by National Natural Science Foundation of China(NSFC)(62375238,92150302,U23B2047,and 62321166651)Zhejiang Provincial Major Research and Development Program under Grant 2021C01199The Fundamental Research Funds for the Central Universities,The Leading Innovative and Entrepreneur Team Introduction Program of Zhejiang(2021R01001).
文摘Structured light carrying angular momentum,such as spin angular momentum(SAM)and orbital angular momentum(OAM),has been at the core of new science and applications,driving the need for compact on-chip sources.While many static on-chip solutions have been demonstrated,as well as on-chip sources of free-space modes,no architecture that is fully reconfigurable in all angular momentum states and all on-chip has so far been possible.Here we report the first all-on-chip structured light generator for the creation of both scalar and vectorial angular momentum beams,facilitated through a silicon-on-insulator(SOI)chip with a silica mode multiplexer(silica chip).We selectively stimulate six linearly-polarized(LP)modes of the silica multimode bus waveguide,precisely controlling the modal powers and phases with the SOI chip.This allows us to tailor arbitrary superpositions of the mode set thus synthesizing common cylindrical vector vortex beams as well as OAM beams of controlled spin and topological charge.Our compact structured light generator exhibits high switching speed and operates across the telecom band,paving the way for applications such as optical communication and integrated quantum technologies.
基金111 Project(B17035)National Natural Science Foundation of China(U20B2059,62575227,62231021,61621005,62201613)+1 种基金Shanghai Aerospace Science and Technology Innovation Foundation(SAST-2022-069)Fundamental Research Funds for the Central Universities(ZYTS25121).
文摘Atmospheric turbulence degrades the performance of free-space optical(FSO)communication and remote sensing systems by introducing phase and intensity distortions.While a majority of research focuses on mitigating these effects to ensure robust signal transmission,an underexplored alternative is to leverage the transformation of structured light to characterize the turbulent medium itself.Here,we introduce a deep learning framework that fuses post-propagation intensity speckle patterns and orbital angular momentum(OAM)spectral data for atmospheric turbulence parameter inference.Our architecture,based on a modified InceptionNet backbone,is optimized to extract and integrate multi-scale features from these distinct optical modalities.This multimodal approach achieves validation accuracies exceeding 80%,substantially outperforming conventional single-modality baselines.The framework demonstrates high inference accuracy and enhanced training stability across a broad range of simulated turbulent conditions,quantified by varying Fried parameters(r_(0))and Reynolds numbers(Re).This work presents a scalable and data-efficient method for turbulence characterization,offering a pathway toward robust environmental sensing and the optimization of dynamic FSO systems.
基金Support from grants 12274299,92050202 and 22QA1406600 are gratefully acknowledged.
文摘Topology is usually perceived intrinsically immutable for a given object.We argue that optical topologies do not immediately enjoy such benefits.Using'optical skyrmions'as an example,we show that they will exhibit varying textures and topological invariants(skyrmion numbers),depending on how to construct the skyrmion vector when projecting from real to parameter space.We demonstrate the fragility of optical skyrmions under a ubiquitous scenario-simple reflection off an optical mirror.Optical topology is not without benefit,but it must not be assumed.
基金The authors thank professor Dayong Jin for his advice on enhancing the draft.C.H.would like to thank the support of the Junior Research Fellowship from St.John’s College,University of Oxford.
文摘Structured light refers to the arbitrarily tailoring of optical fields in all their degrees of freedom(DoFs),from spatial to temporal.Although orbital angular momentum(OAM)is perhaps the most topical example,and celebrating 30 years since its connection to the spatial structure of light,control over other DoFs is slowly gaining traction,promising access to higher-dimensional forms of structured light.Nevertheless,harnessing these new DoFs in quantum and classical states remains challenging,with the toolkit still in its infancy.In this perspective,we discuss methods,challenges,and opportunities for the creation,detection,and control of multiple DoFs for higher-dimensional structured light.We present a roadmap for future development trends,from fundamental research to applications,concentrating on the potential for larger-capacity,higher-security information processing and communication,and beyond.
基金the National Research Foundation and the CSIR-NRF Rental Pool Program.
文摘Structured light is routinely used in free-space optical communication channels,both classical and quantum,where information is encoded in the spatial structure of the mode for increased bandwidth.Both real-world and experimentally simulated turbulence conditions have revealed that free-space structured light modes are perturbed in some manner by turbulence,resulting in both amplitude and phase distortions,and consequently,much attention has focused on whether one mode type is more robust than another,but with seemingly inconclusive and contradictory results.We present complex forms of structured light that are invariant under propagation through the atmosphere:the true eigenmodes of atmospheric turbulence.We provide a theoretical procedure for obtaining these eigenmodes and confirm their invariance both numerically and experimentally.Although we have demonstrated the approach on atmospheric turbulence,its generality allows it to be extended to other channels too,such as aberrated paths,underwater,and in optical fiber.
基金support from the German Research Foundation DFG(EXC 1003–CiM,TRR61)CRG from the Claude Leon foundationBN from the National Research Foundation of South Africa.
文摘It is well known that the entanglement of a quantum state is invariant under local unitary transformations.This rule dictates,for example,that the entanglement of internal degrees of freedom of a photon remains invariant during free-space propagation.Here,we outline a scenario in which this paradigm does not hold.Using local Bell states engineered from classical vector vortex beams with non-separable degrees of freedom,the so-called classically entangled states,we demonstrate that the entanglement evolves during propagation,oscillating between maximally entangled(purely vector)and product states(purely scalar).We outline the spin–orbit interaction behind these novel propagation dynamics and confirm the results experimentally,demonstrating spin–orbit coupling in paraxial beams.This demonstration highlights a hitherto unnoticed property of classical entanglement and simultaneously offers a device for the on-demand delivery of vector states to targets,for example,for dynamic laser materials processing,switchable resolution within stimulated emission depletion(STED)systems,and a tractor beam for entanglement.
基金Marie S.-Curie MULTIPLY Fellowship (GA713694)National Key Research and Development Program of China (2017YFB1104500)+2 种基金National Natural Science Foundation of China (61975087)Natural Science Foundation of Beijing Municipality (4172030)Beijing Young Talents Support Project (2017000020124G044).
文摘Vector beams,non-separable in spatial mode and polarisation,have emerged as enabling tools in many diverse applications,from communication to imaging.This applicability has been achieved by sophisticated laser designs controlling the spin and orbital angular momentum,but so far is restricted to only two-dimensional states.Here we demonstrate the first vectorially structured light created and fully controlled in eight dimensions,a new state-of-the-art.We externally modulate our beam to control,for the frst time,the complete set of classical Greenberger-Horne-Zeilinger(GHZ)states in paraxial structured light beams,in analogy with high-dimensional multi-partite quantum entangled states,and introduce a new tomography method to verify their fidelity.Our complete theoretical framework reveals a rich parameter space for further extending the dimensionality and degrees of freedom,opening new pathways for vetorilly structured light in the classical and quantum regimes.
文摘A well-known defect introduced during the fabrication of GRIN lenses can be exploited for the creation,detection and wave-guiding of exotic forms of vectorial structured light,bringing the toolkit into the realm of common laboratory optics.
基金the funding from the Department of Science and Innovation as well as the National Research Foundation in South AfricaSupport from the Italian Ministry of Research(MUR)through the PRIN 2017 project“Interacting photons in polariton circuits”(INPho POL)and the PNRR MUR project PE0000023-NQSTI is acknowledgedsupport from the Italian Space Agency through the“Highdimensional quantum information”project
文摘Structured light,where complex optical fields are tailored in all their degrees of freedom,has become highly topical of late,advanced by a sophisticated toolkit comprising both linear and nonlinear optics.Removing undesired structure from light is far less developed,leveraging mostly on inverting the distortion,e.g.,with adaptive optics or the inverse transmission matrix of a complex channel,both requiring that the distortion be fully characterized through appropriate measurement.We show that distortions in spatially structured light can be corrected through difference-frequency generation in a nonlinear crystal without any need for the distortion to be known.We demonstrate the versatility of our approach using a wide range of aberrations and structured light modes,including higher-order orbital angular momentum(OAM)beams,showing excellent recovery of the original undistorted field.To highlight the efficacy of this process,we deploy the system in a prepare-and-measure communications link with OAM,showing minimal cross talk even when the transmission channel is highly aberrated,and outline how the approach could be extended to alternative experimental modalities and nonlinear processes.Our demonstration of light-correcting light without the need for measurement opens an approach to measurement-free error correction for classical and quantum structured light,with direct applications in imaging,sensing,and communication.
基金Consejo Nacional de Ciencia y Tecnología(PN2016-3140)National Natural Science Foundation of China(61975047).
文摘One of the most prominent features of quantum entanglement is its invariability under local unitary transformations,which implies that the degree of entanglement or nonseparability remains constant during free-space propagation,true for both quantum and classically entangled modes.Here we demonstrate an exception to this rule using a carefully engineered vectorial light field,and we study its nonseparability dynamics upon free-space propagation.We show that the local nonseparability between the spatial and polarization degrees of freedom dramatically decays to zero while preserving the purity of the state and hence the global nonseparability.We show this by numerical simulations and corroborate it experimentally.Our results evince novel properties of classically entangled modes and point to the need for new measures of nonseparability for such vectorial fields,while paving the way for novel applications for customized structured light.
文摘Orbital angular momentum interactions at the nanoscale have remained elusive because the phase structure becomes unresolved.Now researchers have shown how to overcome this with tightly focused beams,demonstrating a recordhigh six-dimensional encoding in an ultra-dense nanoscale volume.
文摘Controlling light in all its degrees of freedom is steadily gaining traction,extending our familiar 2D transverse forms of electromagnetic waves to include 3D control(all three components of the electric field),and spatiotemporal control for 4D forms of structured light.1 Despite the advances,there still exist solutions to Maxwell’s equations that have not yet been demonstrated,2 hindered by the need to induce higherorder multipoles(beyond dipoles)and toroidal excitations in matter.3 Reporting in Nature Photonics,Qiwen Zhan and colleagues demonstrate the first optical toroidal vortex.4 They bypass the need for exotic materials and rare electronic transitions by exploiting conformal mapping of a space–time shaped vortex pulse,twisting and folding the optical field to form the familiar toroidal nature.Their approach heralds new spatial and temporal control of structured light,with the potential to impact fields from topology to quantum information.
文摘Recently there is an increasing interest in tailored optical fields with complex amplitude, phase and polarization spatial distributions, as well as specifically designed temporal waveforms. Scalar optical vortices carrying orbital angular momentum and vectorial vortices such as radially and azimuthally polarized beams are among the most intensively studied examples.
文摘Nano-structured metasurfaces have to be tailored from artificial atoms that act as toroidal emitters,giving rise to a new form of light long predicted:"flying doughnuts"as propagating spatial-temporal electromagnetic toroidal pulses in both the visible and THz regimes.
文摘High-dimensional quantum states are known to offer advantages over their two-dimensional qubit counterparts,but their preparation and manipulation has been bulky and cumbersome.Now,quantum state control has been demonstrated on-chip with a~1μm2 footprint and nm-scale features,producing up to eight-dimensional quantum states and ushering in a new route to large quantum information encoding on a small footprint.
文摘Transparent objects are invisible to traditional cameras because they can only detect intensity fluctuations,necessitating the need for interferometry followed by computationally intensive digital image processing.Now it is shown that the necessary transformations can be performed optically by combining machine learning and diffractive optics,for a direct in-situ measurement of transparent objects with conventional cameras.
