Planar and ultrathin liquid crystal(LC)polarization optical elements have found promising applications in augmented reality(AR),virtual reality(VR),and photonic devices.In this paper,we give a comprehensive review on ...Planar and ultrathin liquid crystal(LC)polarization optical elements have found promising applications in augmented reality(AR),virtual reality(VR),and photonic devices.In this paper,we give a comprehensive review on the operation principles,device fabrication,and performance of these optical elements.Optical simulations methods for optimizing the device performance are discussed in detail.Finally,some potential applications of these devices in AR and VR systems are illustrated and analyzed.展开更多
Let there be light-to change the world we want to be!Over the past several decades,and ever since the birth of the first laser,mankind has witnessed the development of the science of light,as light-based technologies ...Let there be light-to change the world we want to be!Over the past several decades,and ever since the birth of the first laser,mankind has witnessed the development of the science of light,as light-based technologies have revolutionarily changed our lives.Needless to say,photonics has now penetrated into many aspects of science and technology,turning into an important and dynamically changing field of increasing interdisciplinary interest.In this inaugural issue of eLight,we highlight a few emerging trends in photonics that we think are likely to have major impact at least in the upcoming decade,spanning from integrated quantum photonics and quantum computing,through topological/non-Hermitian photonics and topological insulator lasers,to AI-empowered nanophotonics and photonic machine learning.This Perspective is by no means an attempt to summarize all the latest advances in photonics,yet we wish our subjective vision could fuel inspiration and foster excitement in scientific research especially for young researchers who love the science of light.展开更多
Imaging through diffusers presents a challenging problem with various digital image reconstruction solutions demonstrated to date using computers.Here,we present a computer-free,all-optical image reconstruction method...Imaging through diffusers presents a challenging problem with various digital image reconstruction solutions demonstrated to date using computers.Here,we present a computer-free,all-optical image reconstruction method to see through random diffusers at the speed of light.Using deep learning,a set of transmissive diffractive surfaces are trained to all-optically reconstruct images of arbitrary objects that are completely covered by unknown,random phase diffusers.After the training stage,which is a one-time effort,the resulting diffractive surfaces are fabricated and form a passive optical network that is physically positioned between the unknown object and the image plane to all-optically reconstruct the object pattern through an unknown,new phase diffuser.We experimentally demonstrated this concept using coherent THz illumination and all-optically reconstructed objects distorted by unknown,random diffusers,never used during training.Unlike digital methods,all-optical diffractive reconstructions do not require power except for the illumination light.This diffractive solution to see through diffusers can be extended to other wavelengths,and might fuel various applications in biomedical imaging,astronomy,atmospheric sciences,oceanography,security,robotics,autonomous vehicles,among many others.展开更多
Controlling electromagnetic waves and information simultaneously by information metasurfaces is of central importance in modern society.Intelligent metasurfaces are smart platforms to manipulate the wave-information-m...Controlling electromagnetic waves and information simultaneously by information metasurfaces is of central importance in modern society.Intelligent metasurfaces are smart platforms to manipulate the wave-information-matter interactions without manual intervention by synergizing engineered ultrathin structures with active devices and algorithms,which evolve from the passive composite materials for tailoring wave-matter interactions that cannot be achieved in nature.Here,we review the recent progress of intelligent metasurfaces in wave-information-matter controls by providing the historical background and underlying physical mechanisms.Then we explore the application of intelligent metasurfaces in developing novel wireless communication architectures,with particular emphasis on metasurface-modulated backscatter wireless communications.We also explore the wave-based computing by using the intelligent metasurfaces,focusing on the emerging research direction in intelligent sensing.Finally,we comment on the challenges and highlight the potential routes for the further developments of the intelligent metasurfaces for controls,communications and computing.展开更多
Optical metamaterials have presented an innovative method of manipulating light.Hyperbolic metamaterials have an extremely high anisotropy with a hyperbolic dispersion relation.They are able to support high-k modes an...Optical metamaterials have presented an innovative method of manipulating light.Hyperbolic metamaterials have an extremely high anisotropy with a hyperbolic dispersion relation.They are able to support high-k modes and exhibit a high density of states which produce distinctive properties that have been exploited in various applications,such as super-resolution imaging,negative refraction,and enhanced emission control.Here,state-of-the-art hyperbolic metamaterials are reviewed,starting from the fundamental principles to applications of artificially structured hyperbolic media to suggest ways to fuse natural two-dimensional hyperbolic materials.The review concludes by indicating the current challenges and our vision for future applications of hyperbolic metamaterials.展开更多
The use of optical tweezers to measure forces acting upon microscopic particles has revolutionised fields from material science to cell biology.However,despite optical control capabilities,this technology is highly co...The use of optical tweezers to measure forces acting upon microscopic particles has revolutionised fields from material science to cell biology.However,despite optical control capabilities,this technology is highly constrained by the material properties of the probe,and its use may be limited due to concerns about the effect on biological processes.Here we present a novel,optically controlled trapping method based on light-induced hydrodynamic flows.Specifically,we leverage optical control capabilities to convert a translationally invariant topological defect of a flow field into an attractor for colloids in an effectively one-dimensional harmonic,yet freely rotatable system.Circumventing the need to stabilise particle dynamics along an unstable axis,this novel trap closely resembles the isotropic dynamics of optical tweezers.Using magnetic beads,we explicitly show the existence of a linear force-extension relationship that can be used to detect femtoNewton-range forces with sensitivity close to the thermal limit.Our force measurements remove the need for laser-particle contact,while also lifting material constraints,which renders them a particu-larly interesting tool for the life sciences and engineering.展开更多
Two dimensional excitonic devices are of great potential to overcome the dilemma of response time and integration in current generation of electron or/and photon based systems.The ultrashort diffusion length of excito...Two dimensional excitonic devices are of great potential to overcome the dilemma of response time and integration in current generation of electron or/and photon based systems.The ultrashort diffusion length of exciton arising from ultrafast relaxation and low carrier mobility greatly discounts the performance of excitonic devices.Phonon scattering and exciton localization are crucial to understand the modulation of exciton flux in two dimensional disorder energy landscape,which still remain elusive.Here,we report an optimized scheme for exciton diffusion and relaxation dominated by phonon scattering and disorder potentials in WSe2 monolayers.The effective diffusion coefficient is enhanced by>200%at 280 K.The excitons tend to be localized by disorder potentials accompanied by the steadily weakening of phonon scattering when temperature drops to 260 K,and the onset of exciton localization brings forward as decreasing temperature.These findings identify that phonon scattering and disorder potentials are of great importance for long-range exciton diffusion and thermal management in exciton based systems,and lay a firm foundation for the development of functional excitonic devices.展开更多
High-throughput computational imaging requires efficient processing algorithms to retrieve multi-dimensional and multi-scale information.In computational phase imaging,phase retrieval(PR)is required to reconstruct bot...High-throughput computational imaging requires efficient processing algorithms to retrieve multi-dimensional and multi-scale information.In computational phase imaging,phase retrieval(PR)is required to reconstruct both amplitude and phase in complex space from intensity-only measurements.The existing PR algorithms suffer from the tradeoff among low computational complexity,robustness to measurement noise and strong generalization on different modalities.In this work,we report an efficient large-scale phase retrieval technique termed as LPR.It extends the plug-and-play generalized-alternating-projection framework from real space to nonlinear complex space.The alternating projection solver and enhancing neural network are respectively derived to tackle the measurement formation and statistical prior regularization.This framework compensates the shortcomings of each operator,so as to realize high-fidelity phase retrieval with low computational complexity and strong generalization.We applied the technique for a series of computational phase imaging modalities including coherent diffraction imaging,coded diffraction pattern imaging,and Fourier ptychographic microscopy.Extensive simulations and experiments validate that the technique outperforms the existing PR algorithms with as much as 17dB enhancement on signal-to-noise ratio,and more than one order-of-magnitude increased running efficiency.Besides,we for the first time demonstrate ultralarge-scale phase retrieval at the 8K level(7680×4320 pixels)in minute-level time.展开更多
While conventional photodetectors can only measure light intensity,the vectorial light field contains much richer information,including polarization and spectrum,that are essential for numerous applications ranging fr...While conventional photodetectors can only measure light intensity,the vectorial light field contains much richer information,including polarization and spectrum,that are essential for numerous applications ranging from imaging to telecommunication.However,the simultaneous measurement of multi-dimensional light field information typically requires the multiplexing of dispersive or polarization-selective elements,leading to excessive system complexity.Here,we demonstrate a near-infrared spectropolarimeter based on an electrically-tunable liquid crystal metasurface.The tunable metasurface,which acts as an encoder of the vectorial light field,is tailored to support high-quality-factor guided-mode resonances with diverse and anisotropic spectral features,thus allowing the full Stokes parameters and the spectrum of the incident light to be computationally reconstructed with high fidelity.The concept of using a tunable metasurface for multi-dimensional light field encoding may open up new horizons for developing vectorial light field sensors with minimized size,weight,cost,and complexity.展开更多
Privacy protection is a growing concern in the digital era,with machine vision techniques widely used throughout public and private settings.Existing methods address this growing problem by,e.g.,encrypting camera imag...Privacy protection is a growing concern in the digital era,with machine vision techniques widely used throughout public and private settings.Existing methods address this growing problem by,e.g.,encrypting camera images or obscuring/blurring the imaged information through digital algorithms.Here,we demonstrate a camera design that performs class-specific imaging of target objects with instantaneous all-optical erasure of other classes of objects.This diffractive camera consists of transmissive surfaces structured using deep learning to perform selective imaging of target classes of objects positioned at its input field-of-view.After their fabrication,the thin diffractive layers collectively perform optical mode filtering to accurately form images of the objects that belong to a target data class or group of classes,while instantaneously erasing objects of the other data classes at the output field-of-view.Using the same framework,we also demonstrate the design of class-specific permutation and class-specific linear transformation cameras,where the objects of a target data class are pixel-wise permuted or linearly transformed following an arbitrarily selected transformation matrix for all-optical class-specific encryption,while the other classes of objects are irreversibly erased from the output image.The success of class-specific diffractive cameras was experimentally demonstrated using terahertz(THz)waves and 3D-printed diffractive layers that selectively imaged only one class of the MNIST handwritten digit dataset,all-optically erasing the other handwritten digits.This diffractive camera design can be scaled to different parts of the electromagnetic spectrum,including,e.g.,the visible and infrared wavelengths,to provide transformative opportunities for privacy-preserving digital cameras and task-specific data-efficient imaging.展开更多
The power of controlling objects with mind has captivated a popular fascination to human beings.One possible path is to employ brain signal collecting technologies together with emerging programmable metasurfaces(PM),...The power of controlling objects with mind has captivated a popular fascination to human beings.One possible path is to employ brain signal collecting technologies together with emerging programmable metasurfaces(PM),whose functions or operating modes can be switched or customized via on-site programming or pre-defined software.Nevertheless,most of existing PMs are wire-connected to users,manually-controlled and not real-time.Here,we propose the concept of remotely mind-controlled metasurface(RMCM)via brainwaves.Rather than DC voltage from power supply or AC voltages from signal generators,the metasurface is controlled by brainwaves collected in real time and transmitted wirelessly from the user.As an example,we demonstrated a RMCM whose scattering pattern can be altered dynamically according to the user’s brain waves via Bluetooth.The attention intensity information is extracted as the control signal and a mapping between attention intensity and scattering pattern of the metasurface is established.With such a framework,we experimentally demonstrated and verified a prototype of such metasurface system which can be remotely controlled by the user to modify its scattering pattern.This work paves a new way to intelligent metasurfaces and may find applications in health monitoring,5G/6G communications,smart sensors,etc.展开更多
Achieving localization with molecular precision has been of great interest for extending fluorescence microscopy to nanoscopy.MINFLUX pioneers this transition through point spread function(PSF)engineering,yet its perf...Achieving localization with molecular precision has been of great interest for extending fluorescence microscopy to nanoscopy.MINFLUX pioneers this transition through point spread function(PSF)engineering,yet its performance is primarily limited by the signal-to-background ratio.Here we demonstrate theoretically that two-photon MINFLUX(2p-MINFLUX)could double its localization precision through PSF engineering by nonlinear effect.Cramér-Rao Bound(CRB)is studied as the maximum localization precision,and CRB of two-photon MINFLUX is halved compared to single-photon MINFLUX(1p-MINFLUX)in all three dimensions.Meanwhile,in order to achieve same localization precision with 1p-MINFLUX,2p-MINFLUX requires only 1/4 of fluorescence photons.Exploiting simultaneous two-photon excitation of multiple fluorophore species,2p-MINFLUX may have the potential for registration-free nanoscopy and multicolor tracking.展开更多
Nanophotonic platforms such as metasurfaces,achieving arbitrary phase profiles within ultrathin thickness,emerge as miniaturized,ultracompact and kaleidoscopic optical vortex generators.However,it is often required to...Nanophotonic platforms such as metasurfaces,achieving arbitrary phase profiles within ultrathin thickness,emerge as miniaturized,ultracompact and kaleidoscopic optical vortex generators.However,it is often required to segment or interleave independent sub-array metasurfaces to multiplex optical vortices in a single nano-device,which in turn affects the device’s compactness and channel capacity.Here,inspired by phyllotaxis patterns in pine cones and sunflowers,we theoretically prove and experimentally report that multiple optical vortices can be produced in a single compact phyllotaxis nanosieve,both in free space and on a chip,where one meta-atom may contribute to many vortices simultaneously.The time-resolved dynamics of on-chip interference wavefronts between multiple plasmonic vortices was revealed by ultrafast time-resolved photoemission electron microscopy.Our nature-inspired optical vortex generator would facilitate various vortex-related optical applications,including structured wavefront shaping,free-space and plasmonic vortices,and high-capacity information metaphotonics.展开更多
Water plays a vital role in biological metabolism and it would be essential to trace the water content non-invasively,such as leveraging the vibrational absorption peak of the O-H bond.However,due to the lack of an ef...Water plays a vital role in biological metabolism and it would be essential to trace the water content non-invasively,such as leveraging the vibrational absorption peak of the O-H bond.However,due to the lack of an efficient laser source,it was challenging to image the water content in the deep tissue with micron-level spatial resolution.To address this problem,we develop a high-power hybrid optical parametrically-oscillating emitter(HOPE)at 1930 nm,at which the vibrational absorption peak of the O-H bond locates.The maximum pulse energy is over 1.74μJ with a pulse repetition rate of 50 kHz and a pulse width of 15 ns.We employ this laser source in the optical-resolution photoacoustic microscopy(OR-PAM)system to image the water content in the phantom and the biological tissue in vitro.Our 1930-nm OR-PAM could map the water content in the complex tissue environment at high spatial resolution,deep penetration depth,improved sensitivity,and suppressed artifact signal of the lipid.展开更多
Brain-computer interfaces(BCIs),invasive or non-invasive,have projected unparalleled vision and promise for assisting patients in need to better their interaction with the surroundings.Inspired by the BCI-based rehabi...Brain-computer interfaces(BCIs),invasive or non-invasive,have projected unparalleled vision and promise for assisting patients in need to better their interaction with the surroundings.Inspired by the BCI-based rehabilitation technologies for nerve-system impairments and amputation,we propose an electromagnetic brain-computer-metasurface(EBCM)paradigm,regulated by human’s cognition by brain signals directly and non-invasively.We experimentally show that our EBCM platform can translate human’s mind from evoked potentials of P300-based electroencephalography to digital coding information in the electromagnetic domain non-invasively,which can be further processed and transported by an information metasurface in automated and wireless fashions.Directly wireless communications of the human minds are performed between two EBCM operators with accurate text transmissions.Moreover,several other proof-of-concept mind-control schemes are presented using the same EBCM platform,exhibiting flexibly-customized capabilities of information processing and synthesis like visual-beam scanning,wave modulations,and pattern encoding.展开更多
Nanophotonic engineering provides an effective platform to manipulate thermal emission on-demand,enabling unprecedented heat management superior to conventional bulk materials.Amongst a plethora of nanophotonic struct...Nanophotonic engineering provides an effective platform to manipulate thermal emission on-demand,enabling unprecedented heat management superior to conventional bulk materials.Amongst a plethora of nanophotonic structures,symmetries play an important role in controlling radiative heat transfer in both near-field and far-field.In physics,broken symmetries generally increase the degree of freedom in a system,enriching the understanding of physical mechanisms and bringing many exciting opportunities for novel applications.In this review,we discussed the underlying physics and functionalities of nanophotonic structures with broken geometrical symmetries,engineered mode symmetries,and broken reciprocity for the control of thermal emission.We overview a variety of physical phenomena and interesting applications,and provide the outlook for future development.展开更多
Transformation optics has formulated a versatile framework to mold the flow of light and tailor its spatial characteristics at will.Despite its huge success in bringing scientific fiction(such as invisibility cloaking...Transformation optics has formulated a versatile framework to mold the flow of light and tailor its spatial characteristics at will.Despite its huge success in bringing scientific fiction(such as invisibility cloaking)into reality,the coordinate transformation often yields extreme material parameters unfeasible even with metamaterials.Here,we demonstrate a new transformation paradigm based upon the invariance of the eigenspectra of the Hamiltonian of a physical system,enabled by supersymmetry.By creating a gradient-index metamaterial to control the local index variation in a family of isospectral optical potentials,we demonstrate broadband continuous supersymmetric transformation in optics,on a silicon chip,to simultaneously transform the transverse spatial characteristics of multiple optical states for arbitrary steering and switching of light flows.Through a novel synergy of symmetry physics and metamaterials,our work provides an adaptable strategy to conveniently tame the flow of light with full exploitation of its spatial degree of freedom.展开更多
The topological features of optical vortices have been opening opportunities for free-space and on-chip photonic technologies,e.g.,for multiplexed optical communications and robust information transport.In a parallel ...The topological features of optical vortices have been opening opportunities for free-space and on-chip photonic technologies,e.g.,for multiplexed optical communications and robust information transport.In a parallel but disjoint effort,polar anisotropic van der Waals nanomaterials supporting hyperbolic phonon polaritons(HP2s)have been leveraged to drastically boost light-matter interactions.So far HP2 studies have been mainly focusing on the control of their amplitude and scale features.Here we report the generation and observation of mid-infrared hyperbolic polariton vortices(HP2Vs)associated with reconfigurable topological charges.Spiral-shaped gold disks coated with a flake of hexagonal boron nitride are exploited to tailor spin-orbit interactions and realise deeply subwavelength HP2Vs.The complex interplay between excitation spin,spiral geometry and HP2 dispersion enables robust reconfigurability of the associated topological charges.Our results reveal unique opportunities to extend the application of HP2s into topological photonics,quantum information processing by integrating these phenomena with single-photon emitters,robust on-chip optical applications,sensing and nanoparticle manipulation.展开更多
Modern optical imaging techniques provide powerful tools for observing cortical structure and functions at high resolutions.Various skull windows have been established for different applications of cortical imaging,an...Modern optical imaging techniques provide powerful tools for observing cortical structure and functions at high resolutions.Various skull windows have been established for different applications of cortical imaging,and each has its advantages and limitations.Most critical of the limitations,none of the current skull windows is suitable for observing the responses to some acute craniocerebral injuries on a large scale and at high resolution.Here,we developed a“Through-Intact-Skull(TIS)window”that enables the observation of an immune response on a bilateral cortical scale and at single-cell resolution after traumatic brain injury without affecting the pathological environment of the brain.The TIS window also has the advantages of craniotomy-freeness,centimeter-field of view,synaptic resolution,large imaging depth,long-term observation capability,and suitability for awake mice.Therefore,the TIS window is a promising new approach for intravital cortical microscopy in basic research in neuroscience.展开更多
Neutron-transmutation doping(NTD)has been demonstrated for the first time in this work for substitutional introduction of tin(Sn)shallow donors into two-dimensional(2D)layered indium selenide(InSe)to manipulate electr...Neutron-transmutation doping(NTD)has been demonstrated for the first time in this work for substitutional introduction of tin(Sn)shallow donors into two-dimensional(2D)layered indium selenide(InSe)to manipulate electron transfer and charge carrier dynamics.Multidisciplinary study including density functional theory,transient optical absorption,and FET devices have been carried out to reveal that the field effect electron mobility of the fabricated phototransistor is increased 100-fold due to the smaller electron effective mass and longer electron life time in the Sn-doped InSe.The responsivity of the Sn-doped InSe based phototransistor is accordingly enhanced by about 50 times,being as high as 397 A/W.The results show that NTD is a highly effective and controllable doping method,possessing good compatibility with the semiconductor manufacturing process,even after device fabrication,and can be carried out without introducing any contamination,which is radically different from traditional doping methods.展开更多
文摘Planar and ultrathin liquid crystal(LC)polarization optical elements have found promising applications in augmented reality(AR),virtual reality(VR),and photonic devices.In this paper,we give a comprehensive review on the operation principles,device fabrication,and performance of these optical elements.Optical simulations methods for optimizing the device performance are discussed in detail.Finally,some potential applications of these devices in AR and VR systems are illustrated and analyzed.
基金support from the National Key R&D Program of China under Grant(No.2017YFA0303800).MS acknowledges support from the Israel Science Foundation.
文摘Let there be light-to change the world we want to be!Over the past several decades,and ever since the birth of the first laser,mankind has witnessed the development of the science of light,as light-based technologies have revolutionarily changed our lives.Needless to say,photonics has now penetrated into many aspects of science and technology,turning into an important and dynamically changing field of increasing interdisciplinary interest.In this inaugural issue of eLight,we highlight a few emerging trends in photonics that we think are likely to have major impact at least in the upcoming decade,spanning from integrated quantum photonics and quantum computing,through topological/non-Hermitian photonics and topological insulator lasers,to AI-empowered nanophotonics and photonic machine learning.This Perspective is by no means an attempt to summarize all the latest advances in photonics,yet we wish our subjective vision could fuel inspiration and foster excitement in scientific research especially for young researchers who love the science of light.
基金The authors acknowledge the U.S.National Science Foundation and Fujikura.
文摘Imaging through diffusers presents a challenging problem with various digital image reconstruction solutions demonstrated to date using computers.Here,we present a computer-free,all-optical image reconstruction method to see through random diffusers at the speed of light.Using deep learning,a set of transmissive diffractive surfaces are trained to all-optically reconstruct images of arbitrary objects that are completely covered by unknown,random phase diffusers.After the training stage,which is a one-time effort,the resulting diffractive surfaces are fabricated and form a passive optical network that is physically positioned between the unknown object and the image plane to all-optically reconstruct the object pattern through an unknown,new phase diffuser.We experimentally demonstrated this concept using coherent THz illumination and all-optically reconstructed objects distorted by unknown,random diffusers,never used during training.Unlike digital methods,all-optical diffractive reconstructions do not require power except for the illumination light.This diffractive solution to see through diffusers can be extended to other wavelengths,and might fuel various applications in biomedical imaging,astronomy,atmospheric sciences,oceanography,security,robotics,autonomous vehicles,among many others.
基金National Key Research and Development Program of China under Grant Nos.2021YFA1401002,2017YFA0700201,2017YFA0700202,and 2017YFA0700203,and the 111 Project under Grant No.111-2-05.
文摘Controlling electromagnetic waves and information simultaneously by information metasurfaces is of central importance in modern society.Intelligent metasurfaces are smart platforms to manipulate the wave-information-matter interactions without manual intervention by synergizing engineered ultrathin structures with active devices and algorithms,which evolve from the passive composite materials for tailoring wave-matter interactions that cannot be achieved in nature.Here,we review the recent progress of intelligent metasurfaces in wave-information-matter controls by providing the historical background and underlying physical mechanisms.Then we explore the application of intelligent metasurfaces in developing novel wireless communication architectures,with particular emphasis on metasurface-modulated backscatter wireless communications.We also explore the wave-based computing by using the intelligent metasurfaces,focusing on the emerging research direction in intelligent sensing.Finally,we comment on the challenges and highlight the potential routes for the further developments of the intelligent metasurfaces for controls,communications and computing.
基金POSCO-POSTECH-RIST Convergence Research Center program funded by POSCOPOSTECH-Samsung Semiconductor Research Center(IO201215-08187-01)funded by Samsung ElectronicsNational Research Foundation(NRF)grant(NRF-2019R1A2C3003129)funded by the Ministry of Science and ICT,Republic of Korea.
文摘Optical metamaterials have presented an innovative method of manipulating light.Hyperbolic metamaterials have an extremely high anisotropy with a hyperbolic dispersion relation.They are able to support high-k modes and exhibit a high density of states which produce distinctive properties that have been exploited in various applications,such as super-resolution imaging,negative refraction,and enhanced emission control.Here,state-of-the-art hyperbolic metamaterials are reviewed,starting from the fundamental principles to applications of artificially structured hyperbolic media to suggest ways to fuse natural two-dimensional hyperbolic materials.The review concludes by indicating the current challenges and our vision for future applications of hyperbolic metamaterials.
基金We thank Iain Patten for valuable discussions on the structure and layout of the manuscript.IDS kindly acknowledges funding from the Life grant by Volkswagen Foundation(Grant No.92772).
文摘The use of optical tweezers to measure forces acting upon microscopic particles has revolutionised fields from material science to cell biology.However,despite optical control capabilities,this technology is highly constrained by the material properties of the probe,and its use may be limited due to concerns about the effect on biological processes.Here we present a novel,optically controlled trapping method based on light-induced hydrodynamic flows.Specifically,we leverage optical control capabilities to convert a translationally invariant topological defect of a flow field into an attractor for colloids in an effectively one-dimensional harmonic,yet freely rotatable system.Circumventing the need to stabilise particle dynamics along an unstable axis,this novel trap closely resembles the isotropic dynamics of optical tweezers.Using magnetic beads,we explicitly show the existence of a linear force-extension relationship that can be used to detect femtoNewton-range forces with sensitivity close to the thermal limit.Our force measurements remove the need for laser-particle contact,while also lifting material constraints,which renders them a particu-larly interesting tool for the life sciences and engineering.
基金National Key Research and Development Program of China(Grant No.2017YFA0206000)eijing Natural Science Foundation(Grant No.Z180011)+1 种基金National Science Foundation of China(Grant Nos.12027807,12104241 and 61521004)roject funded by China Postdoctoral Science Foundation(Grant No.2019M660283)。
文摘Two dimensional excitonic devices are of great potential to overcome the dilemma of response time and integration in current generation of electron or/and photon based systems.The ultrashort diffusion length of exciton arising from ultrafast relaxation and low carrier mobility greatly discounts the performance of excitonic devices.Phonon scattering and exciton localization are crucial to understand the modulation of exciton flux in two dimensional disorder energy landscape,which still remain elusive.Here,we report an optimized scheme for exciton diffusion and relaxation dominated by phonon scattering and disorder potentials in WSe2 monolayers.The effective diffusion coefficient is enhanced by>200%at 280 K.The excitons tend to be localized by disorder potentials accompanied by the steadily weakening of phonon scattering when temperature drops to 260 K,and the onset of exciton localization brings forward as decreasing temperature.These findings identify that phonon scattering and disorder potentials are of great importance for long-range exciton diffusion and thermal management in exciton based systems,and lay a firm foundation for the development of functional excitonic devices.
基金supported by the National Natural Science Foundation of China(Nos.61971045,61827901,61991451)National Key R&D Program(Grant No.2020YFB0505601)Fundamental Research Funds for the Central Universities(Grant No.3052019024).
文摘High-throughput computational imaging requires efficient processing algorithms to retrieve multi-dimensional and multi-scale information.In computational phase imaging,phase retrieval(PR)is required to reconstruct both amplitude and phase in complex space from intensity-only measurements.The existing PR algorithms suffer from the tradeoff among low computational complexity,robustness to measurement noise and strong generalization on different modalities.In this work,we report an efficient large-scale phase retrieval technique termed as LPR.It extends the plug-and-play generalized-alternating-projection framework from real space to nonlinear complex space.The alternating projection solver and enhancing neural network are respectively derived to tackle the measurement formation and statistical prior regularization.This framework compensates the shortcomings of each operator,so as to realize high-fidelity phase retrieval with low computational complexity and strong generalization.We applied the technique for a series of computational phase imaging modalities including coherent diffraction imaging,coded diffraction pattern imaging,and Fourier ptychographic microscopy.Extensive simulations and experiments validate that the technique outperforms the existing PR algorithms with as much as 17dB enhancement on signal-to-noise ratio,and more than one order-of-magnitude increased running efficiency.Besides,we for the first time demonstrate ultralarge-scale phase retrieval at the 8K level(7680×4320 pixels)in minute-level time.
基金National Natural Science Foundation of China(61975251,62135008)Guoqiang Institute,Tsinghua University。
文摘While conventional photodetectors can only measure light intensity,the vectorial light field contains much richer information,including polarization and spectrum,that are essential for numerous applications ranging from imaging to telecommunication.However,the simultaneous measurement of multi-dimensional light field information typically requires the multiplexing of dispersive or polarization-selective elements,leading to excessive system complexity.Here,we demonstrate a near-infrared spectropolarimeter based on an electrically-tunable liquid crystal metasurface.The tunable metasurface,which acts as an encoder of the vectorial light field,is tailored to support high-quality-factor guided-mode resonances with diverse and anisotropic spectral features,thus allowing the full Stokes parameters and the spectrum of the incident light to be computationally reconstructed with high fidelity.The concept of using a tunable metasurface for multi-dimensional light field encoding may open up new horizons for developing vectorial light field sensors with minimized size,weight,cost,and complexity.
基金The Ozcan Research Group at UCLA acknowledges the support of ONR(Grant#N00014-22-1-2016)Jarrahi Research Group at UCLA acknowledges the support of the Department of Energy(Grant#DE-SC0016925).
文摘Privacy protection is a growing concern in the digital era,with machine vision techniques widely used throughout public and private settings.Existing methods address this growing problem by,e.g.,encrypting camera images or obscuring/blurring the imaged information through digital algorithms.Here,we demonstrate a camera design that performs class-specific imaging of target objects with instantaneous all-optical erasure of other classes of objects.This diffractive camera consists of transmissive surfaces structured using deep learning to perform selective imaging of target classes of objects positioned at its input field-of-view.After their fabrication,the thin diffractive layers collectively perform optical mode filtering to accurately form images of the objects that belong to a target data class or group of classes,while instantaneously erasing objects of the other data classes at the output field-of-view.Using the same framework,we also demonstrate the design of class-specific permutation and class-specific linear transformation cameras,where the objects of a target data class are pixel-wise permuted or linearly transformed following an arbitrarily selected transformation matrix for all-optical class-specific encryption,while the other classes of objects are irreversibly erased from the output image.The success of class-specific diffractive cameras was experimentally demonstrated using terahertz(THz)waves and 3D-printed diffractive layers that selectively imaged only one class of the MNIST handwritten digit dataset,all-optically erasing the other handwritten digits.This diffractive camera design can be scaled to different parts of the electromagnetic spectrum,including,e.g.,the visible and infrared wavelengths,to provide transformative opportunities for privacy-preserving digital cameras and task-specific data-efficient imaging.
基金National Natural Science Foundation of China under Grant Nos.61971435,62101588,62101589National Key Research and Development Program of China(Grant No.:SQ2017YFA0700201)+1 种基金C.-W.Q.is supported by a grant(R-261-518-004-720|A-0005947-16-00)from Advanced Research and Technology Innovation Centre(ARTIC)in National University of Singapore.
文摘The power of controlling objects with mind has captivated a popular fascination to human beings.One possible path is to employ brain signal collecting technologies together with emerging programmable metasurfaces(PM),whose functions or operating modes can be switched or customized via on-site programming or pre-defined software.Nevertheless,most of existing PMs are wire-connected to users,manually-controlled and not real-time.Here,we propose the concept of remotely mind-controlled metasurface(RMCM)via brainwaves.Rather than DC voltage from power supply or AC voltages from signal generators,the metasurface is controlled by brainwaves collected in real time and transmitted wirelessly from the user.As an example,we demonstrated a RMCM whose scattering pattern can be altered dynamically according to the user’s brain waves via Bluetooth.The attention intensity information is extracted as the control signal and a mapping between attention intensity and scattering pattern of the metasurface is established.With such a framework,we experimentally demonstrated and verified a prototype of such metasurface system which can be remotely controlled by the user to modify its scattering pattern.This work paves a new way to intelligent metasurfaces and may find applications in health monitoring,5G/6G communications,smart sensors,etc.
基金Beijing Natural Science Foundation(JQ18019)National Natural Science Foundation of China(62025501,31971376,61729501)+1 种基金State Key Research Development Program of China(2017YFC0110202)Shenzhen Science and Technology Program(KQTD20170810110913065)。
文摘Achieving localization with molecular precision has been of great interest for extending fluorescence microscopy to nanoscopy.MINFLUX pioneers this transition through point spread function(PSF)engineering,yet its performance is primarily limited by the signal-to-background ratio.Here we demonstrate theoretically that two-photon MINFLUX(2p-MINFLUX)could double its localization precision through PSF engineering by nonlinear effect.Cramér-Rao Bound(CRB)is studied as the maximum localization precision,and CRB of two-photon MINFLUX is halved compared to single-photon MINFLUX(1p-MINFLUX)in all three dimensions.Meanwhile,in order to achieve same localization precision with 1p-MINFLUX,2p-MINFLUX requires only 1/4 of fluorescence photons.Exploiting simultaneous two-photon excitation of multiple fluorophore species,2p-MINFLUX may have the potential for registration-free nanoscopy and multicolor tracking.
基金supported by the National Research Foundation,Prime Minister’s Office,Singapore under Competitive Research Program Award NRF-CRP22-2019-0006the grant(R-261-518-004-720)from Advanced Research and Technology Innovation Centre(ARTIC)+4 种基金the Deutsche Forschungsgemeinschaft(DFG,German Research Foundation)-Project-ID 278162697-SFB 1242ERC Advanced Grant Complex Plan,BMBF,DFG and BW-Stiftungthe Research Grants Council of Hong Kong(CRF Grant No.C6013-18G)the City University of Hong Kong(Project No.9610434)the support from A*STAR under its AME YIRG Grant(Award No.A2084c0172).
文摘Nanophotonic platforms such as metasurfaces,achieving arbitrary phase profiles within ultrathin thickness,emerge as miniaturized,ultracompact and kaleidoscopic optical vortex generators.However,it is often required to segment or interleave independent sub-array metasurfaces to multiplex optical vortices in a single nano-device,which in turn affects the device’s compactness and channel capacity.Here,inspired by phyllotaxis patterns in pine cones and sunflowers,we theoretically prove and experimentally report that multiple optical vortices can be produced in a single compact phyllotaxis nanosieve,both in free space and on a chip,where one meta-atom may contribute to many vortices simultaneously.The time-resolved dynamics of on-chip interference wavefronts between multiple plasmonic vortices was revealed by ultrafast time-resolved photoemission electron microscopy.Our nature-inspired optical vortex generator would facilitate various vortex-related optical applications,including structured wavefront shaping,free-space and plasmonic vortices,and high-capacity information metaphotonics.
基金This project is funded by Research Grants Council of the Hong Kong Special Administrative Region,China(HKU 17200219,HKU 17209018,E-HKU701/17,CityU T42-103/16-N,and HKU C7047-16G)Natural Science Foundation of China(N_HKU712/16)。
文摘Water plays a vital role in biological metabolism and it would be essential to trace the water content non-invasively,such as leveraging the vibrational absorption peak of the O-H bond.However,due to the lack of an efficient laser source,it was challenging to image the water content in the deep tissue with micron-level spatial resolution.To address this problem,we develop a high-power hybrid optical parametrically-oscillating emitter(HOPE)at 1930 nm,at which the vibrational absorption peak of the O-H bond locates.The maximum pulse energy is over 1.74μJ with a pulse repetition rate of 50 kHz and a pulse width of 15 ns.We employ this laser source in the optical-resolution photoacoustic microscopy(OR-PAM)system to image the water content in the phantom and the biological tissue in vitro.Our 1930-nm OR-PAM could map the water content in the complex tissue environment at high spatial resolution,deep penetration depth,improved sensitivity,and suppressed artifact signal of the lipid.
基金National Key Research and Development Program of China(2017YFA0700201,2017YFA0700202,and 2017YFA0700203)Major Project of Natural Science Foundation of Jiangsu Province(BK20212002)+9 种基金National Natural Science Foundation of China(61871127,61735010,61731010,61890544,61801117,61722106,61701107,61701108,61701246,61631007,61633010,61876064,62076099,61731010,and 11874142)State Key Laboratory of Millimeter Waves,Southeast University,China(K201924)Fundamental Research Funds for the Central Universities(2242018R30001)111 Project(111-2-05)Fund for International Cooperation and Exchange of National Natural Science Foundation of China(61761136007)Key R&D Program of Guangdong Province(2018B030339001)Key Realm R&D Program of Guangzhou(202007030007)Guangdong Basic and Applied Basic Research Foundation(2019A1515011773)Pearl River S&T Nova Program of Guangzhou(201906010043)C.-W.Q.acknowledges the financial support from the grant R-261-518-004-720 from Advanced Research and Technology Innovation Centre(ARTIC)。
文摘Brain-computer interfaces(BCIs),invasive or non-invasive,have projected unparalleled vision and promise for assisting patients in need to better their interaction with the surroundings.Inspired by the BCI-based rehabilitation technologies for nerve-system impairments and amputation,we propose an electromagnetic brain-computer-metasurface(EBCM)paradigm,regulated by human’s cognition by brain signals directly and non-invasively.We experimentally show that our EBCM platform can translate human’s mind from evoked potentials of P300-based electroencephalography to digital coding information in the electromagnetic domain non-invasively,which can be further processed and transported by an information metasurface in automated and wireless fashions.Directly wireless communications of the human minds are performed between two EBCM operators with accurate text transmissions.Moreover,several other proof-of-concept mind-control schemes are presented using the same EBCM platform,exhibiting flexibly-customized capabilities of information processing and synthesis like visual-beam scanning,wave modulations,and pattern encoding.
基金S.F.acknowledges the support of the US Department of Energy(grant no.DE-FG02-07ER46426)W.L.acknowledges the support of the National Natural Science Foundation of China(grant nos.62134009,62121005)Development Program of the Science and Technology of Jilin Province(20200802001GH).
文摘Nanophotonic engineering provides an effective platform to manipulate thermal emission on-demand,enabling unprecedented heat management superior to conventional bulk materials.Amongst a plethora of nanophotonic structures,symmetries play an important role in controlling radiative heat transfer in both near-field and far-field.In physics,broken symmetries generally increase the degree of freedom in a system,enriching the understanding of physical mechanisms and bringing many exciting opportunities for novel applications.In this review,we discussed the underlying physics and functionalities of nanophotonic structures with broken geometrical symmetries,engineered mode symmetries,and broken reciprocity for the control of thermal emission.We overview a variety of physical phenomena and interesting applications,and provide the outlook for future development.
基金U.S.Army Research Office(ARO)(W911NF-19-1-0249 and W911NF-18-1-0348)National Science Foundation(NSF)(CMMI-2037097).
文摘Transformation optics has formulated a versatile framework to mold the flow of light and tailor its spatial characteristics at will.Despite its huge success in bringing scientific fiction(such as invisibility cloaking)into reality,the coordinate transformation often yields extreme material parameters unfeasible even with metamaterials.Here,we demonstrate a new transformation paradigm based upon the invariance of the eigenspectra of the Hamiltonian of a physical system,enabled by supersymmetry.By creating a gradient-index metamaterial to control the local index variation in a family of isospectral optical potentials,we demonstrate broadband continuous supersymmetric transformation in optics,on a silicon chip,to simultaneously transform the transverse spatial characteristics of multiple optical states for arbitrary steering and switching of light flows.Through a novel synergy of symmetry physics and metamaterials,our work provides an adaptable strategy to conveniently tame the flow of light with full exploitation of its spatial degree of freedom.
基金Office of Naval Research(Grant No.N00014-19-1-2011)Vannevar Bush Faculty Fellowship,Air Force Office of Scientific Research MURI program,A*STAR AME Young Individual Research Grant(YIRG,No.A2084c0172)+4 种基金National Research Foundation Singapore(CRP22-2019-0006)Advanced Research and Technology Innovation Centre(No.R-261-518-004-720)National Science Foundation under Grant No.2044281Elemental Strategy Initiative conducted by MEXT,Japan,Grant Number JPMXP0112101001JSPS KAKENHI Grant Number JP20H00354。
文摘The topological features of optical vortices have been opening opportunities for free-space and on-chip photonic technologies,e.g.,for multiplexed optical communications and robust information transport.In a parallel but disjoint effort,polar anisotropic van der Waals nanomaterials supporting hyperbolic phonon polaritons(HP2s)have been leveraged to drastically boost light-matter interactions.So far HP2 studies have been mainly focusing on the control of their amplitude and scale features.Here we report the generation and observation of mid-infrared hyperbolic polariton vortices(HP2Vs)associated with reconfigurable topological charges.Spiral-shaped gold disks coated with a flake of hexagonal boron nitride are exploited to tailor spin-orbit interactions and realise deeply subwavelength HP2Vs.The complex interplay between excitation spin,spiral geometry and HP2 dispersion enables robust reconfigurability of the associated topological charges.Our results reveal unique opportunities to extend the application of HP2s into topological photonics,quantum information processing by integrating these phenomena with single-photon emitters,robust on-chip optical applications,sensing and nanoparticle manipulation.
基金National Natural Science Foundation of China(NSFC)(Grant Nos.61860206009,81870934,82001877,61975172,61735016,91632105,81961128029,81961138015)National Key Research and Development Program of China(2017YFA0700501)+2 种基金China Postdoctoral Science Foundation-funded project(Nos.BX20190131,2019M662633)Innovation Project of Optics Valley Laboratory(Grant No.OVL2021BG011)Funding from the Innovation Fund of WNLO,and Fundamental Research Funds for the Central Universities(Nos.2020-KYY-511108-0007,2019QNA5001).
文摘Modern optical imaging techniques provide powerful tools for observing cortical structure and functions at high resolutions.Various skull windows have been established for different applications of cortical imaging,and each has its advantages and limitations.Most critical of the limitations,none of the current skull windows is suitable for observing the responses to some acute craniocerebral injuries on a large scale and at high resolution.Here,we developed a“Through-Intact-Skull(TIS)window”that enables the observation of an immune response on a bilateral cortical scale and at single-cell resolution after traumatic brain injury without affecting the pathological environment of the brain.The TIS window also has the advantages of craniotomy-freeness,centimeter-field of view,synaptic resolution,large imaging depth,long-term observation capability,and suitability for awake mice.Therefore,the TIS window is a promising new approach for intravital cortical microscopy in basic research in neuroscience.
基金State Key Research Development Program of China(Grant No.2019YFB2203503)National Natural Science Fund(Grant Nos.61875138,61961136001,62104153,62105211 and U1801254)+2 种基金Natural Science Foundation of Guangdong Province(2018B030306038 and 2020A1515110373)Science and Technology Innovation Commission of Shenzhen(JCYJ20180507182047316 and 20200805132016001)Postdoctoral Science Foundation of China(No.2021M702237)。
文摘Neutron-transmutation doping(NTD)has been demonstrated for the first time in this work for substitutional introduction of tin(Sn)shallow donors into two-dimensional(2D)layered indium selenide(InSe)to manipulate electron transfer and charge carrier dynamics.Multidisciplinary study including density functional theory,transient optical absorption,and FET devices have been carried out to reveal that the field effect electron mobility of the fabricated phototransistor is increased 100-fold due to the smaller electron effective mass and longer electron life time in the Sn-doped InSe.The responsivity of the Sn-doped InSe based phototransistor is accordingly enhanced by about 50 times,being as high as 397 A/W.The results show that NTD is a highly effective and controllable doping method,possessing good compatibility with the semiconductor manufacturing process,even after device fabrication,and can be carried out without introducing any contamination,which is radically different from traditional doping methods.