Physics-data-driven intelligent optimization for large-aperture metalenses

Metalenses have gained significant attention and have been widely utilized in optical systems for focusing and imaging,owing to their lightweight,high-integration,and exceptional-flexibility capabilities.Traditional design methods neglect the coupling effect between adjacent meta-atoms,thus harming the practical performance of meta-devices.The existing physical/data-driven optimization algorithms can solve the above problems,but bring significant time costs or require a large number of data-sets.Here,we propose a physics-data-driven method employing an“intelligent optimizer”that enables us to adaptively modify the sizes of the meta-atom according to the sizes of its surrounding ones.The implementation of such a scheme effectively mitigates the undesired impact of local lattice coupling,and the proposed network model works well on thousands of data-sets with a validation loss of 3×10^(−3).Based on the“intelligent optimizer”,a 1-cm-diameter metalens is designed within 3 hours,and the experimental results show that the 1-mm-diameter metalens has a relative focusing efficiency of 93.4%(compared to the ideal focusing efficiency)and a Strehl ratio of 0.94.Compared to previous inverse design method,our method significantly boosts designing efficiency with five orders of magnitude reduction in time.More generally,it may set a new paradigm for devising large-aperture meta-devices.

Improved spatiotemporal resolution of anti-scattering super-resolution label-free microscopy via synthetic wave 3D metalens imaging

Super-resolution(SR)microscopy has dramatically enhanced our understanding of biological processes.However,scattering media in thick specimens severely limits the spatial resolution,often rendering the images unclear or indistinguishable.Additionally,live-cell imaging faces challenges in achieving high temporal resolution for fast-moving subcellular structures.Here,we present the principles of a synthetic wave microscopy(SWM)to extract three-dimensional information from thick unlabeled specimens,where photobleaching and phototoxicity are avoided.SWM exploits multiple-wave interferometry to reveal the specimen’s phase information in the area of interest,which is not affected by the scattering media in the optical path.SWM achieves~0.42λ/NA resolution at an imaging speed of up to 106 pixels/s.SWM proves better temporal resolution and sensitivity than the most conventional microscopes currently available while maintaining exceptional SR and anti-scattering capabilities.Penetrating through the scattering media is challenging for conventional imaging techniques.Remarkably,SWM retains its efficacy even in conditions of low signal-to-noise ratios.It facilitates the visualization of dynamic subcellular structures in live cells,encompassing tubular endoplasmic reticulum(ER),lipid droplets,mitochondria,and lysosomes.

Advancing nonlinear nanophotonics:harnessing membrane metasurfaces for third-harmonic generation and imaging

Dielectric metasurfaces are crucial for enhancing optical nonlinear generation,particularly membrane metasurfaces with multipolar resonances and compact size.Investigating silicon dimer-hole membrane metasurfaces,Rahmani,and Xu show how bound states in the continuum(BICs)can be formed and transformed into quasi-BICs by adjusting hole gaps.This innovation enables efficient conversion of infrared images to visible range,promising applications in nonlinear photonics and near-infrared imaging technologies.

Crosstalk-free achromatic full Stokes imaging polarimetry metasurface enabled by polarization-dependent phase optimization

Imaging polarimetry is one of the most widely used analytical technologies for object detection and analysis.To date,most metasurface-based polarimetry techniques are severely limited by narrow operating bandwidths and inevitable crosstalk,leading to detrimental effects on imaging quality and measurement accuracy.Here,we propose a crosstalkfree broadband achromatic full Stokes imaging polarimeter consisting of polarization-sensitive dielectric metalenses,implemented by the principle of polarization-dependent phase optimization.Compared with the single-polarization optimization method,the average crosstalk has been reduced over three times under incident light with arbitrary polarization ranging from 9μm to 12μm,which guarantees the measurement of the polarization state more precisely.The experimental results indicate that the designed polarization-sensitive metalenses can effectively eliminate the chromatic aberration with polarization selectivity and negligible crosstalk.The measured average relative errors are 7.08%,8.62%,7.15%,and 7.59%at 9.3,9.6,10.3,and 10.6μm,respectively.Simultaneously,the broadband full polarization imaging capability of the device is also verified.This work is expected to have potential applications in wavefront detection,remote sensing,light-field imaging,and so forth.

Symmetry breaking of photonic spin-orbit interactions in metasurfaces

Spin-orbit optical phenomena pertain to the wider class of electromagnetic effects originating from the interaction of the photon spin with the spatial structure and propagation characteristics of an optical wave,mediated by suitable optical media.There are many emerging photonic applications of spin-orbit interactions(SOI)of light,such as control of the optical wave propagation via the spin,enhanced optical manipulation,and generation of structured optical fields.Unfortunately,current applications are based on symmetric SOI,that is,the behaviours of polarized photons with two opposite spins are opposite,leading to the limit of spin-based multiplexers.The symmetry of SOI can be broken in our proposed metasurfaces,consisting of spatially varying birefringence,which can arbitrarily and independently build SOI for two opposite spins without reduction of optical energy usage.We obtain three kinds of dual-functional metasurfaces at visible and infrared wavelengths with high efficiency.Our concept of generation of asymmetric SOI for two spins,using anisotropic metasurfaces,will open new degrees of freedoms for building new types of spin-controlled multifunctional shared-aperture devices for the generation of complex structured optical fields.

All‐metallic wide‐angle metasurfaces for multifunctional polarization manipulation

Optical camouflage is a magical capability of animals as first noticed in 1794 by Erasmus Darwin in Zoonomia,but current biomimetic camouflage strategies cannot be readily applied in complex environments involving multispectral and in particular multi-polarization detection.Here we develop a plasmonic approach toward broadband infrared polarimetric crypsis,where the polarized thermal emission near the pseudo-Brewster angle is the main signal source and no existing polarizing camouflage technique has been discovered in nature.Based on all-metallic subwavelength structures,an electrodynamic resistance-reduction mechanism is proposed to avoid the significant polarization-dependent infrared absorption/radiation.It is also found that the structured metal surface presents giant extrinsic anisotropy regarding the phase shift between orthogonal polarization states,which helps to realize ultrahigh-efficiency and tunable polarization conversion in an unprecedented manner.Finally,we note that the catenary optical theory may provide a useful means to explain and predict these unusual performances.

The Next Breakthroughs of Artificial Intelligence:The Interdisciplinary Nature of AI

1.Introduction Artificial intelligence(AI)is committed to the realization of machine-borne intelligence.The technologies underpinning AI have made huge leaps in the past decade,bringing exciting applications such as language understanding,vision recognition,and intelligent digital assistants.However,contemporary AI systems are good at specific predefined tasks and are unable to learn by themselves from data or from experience,intuitive reasoning,and adaptation.

Off-axis multi-wavelength dispersion controllingmetalens for multi-color imaging

Dispersion control is crucial in optical systems,and chromatic aberration is an important factor affecting imaging quality in imaging systems.Due to the inherent property of materials,dispersion engineering is complex and needs to trade off other aberration in traditional ways.Although metasurface offers an effective method to overcome these limits and results in well-engineered dispersion,off-axis dispersion control is still a challenging topic.In this paper,we design a single-layer metalens which is capable of focusing at three wavelengths(473 nm,532 nm,and 632 nm)with different incident angles(0°,-17°and 17°)into the same point.We also demonstrate that this metalens can provide an alternative for the bulky color synthetic prism in a 3-chips digital micromirror device(DMD)laser projection system.Through this approach,various off-axis dispersion controlling optical devices could be realized.

Plasmonic lithography with 100nm overlay accuracy

In this paper,we demonstrate an auto accurate alignment method to align mask-substrate in the prototype of plasmonic lithography(PL),which is essential for multilayer nanostructure fabrication with high resolution,low cost,high efficiency,and high throughput,such as circuit manufacturing and other applications.We obtained an alignment signal with sensitivity better than 20 nm by using the Moiréfringe image.However,only using the Moiréfringes cannot guarantee the alignment of the mask and the substrate because the Moiréfringe repeats itself when the mask and substrate are offset by a fixed displacement.To eliminate the ambiguity,boxes and the crosses alignment marks are designed beside the grating marks on the substrate and the mask,respectively.A two-step alignment scheme including coarse alignment and fine alignment is explored in the auto alignment system.In the stage of coarse alignment,the edge detection algorithm based on Canny operator is adopted to detect the edges image effectively.In the process of fine alignment,Fourier transform based on Moiréfringe image is obtained to improve the alignment accuracy.In addition,experimental results of overlay indicate that PL can obtain sub-100 nm alignment accuracy over an area of 1 cm^2 using the proposed two-step alignment scheme.Via the substrate-mask mismatch compensation,better stages and precise environment control,it is expected that much higher overlay accuracy is feasible.

Metadata Extended Model Based On Geological Domain Ontology

The current metadata modeling techniques can not meet the needs of knowledge conception expression, knowledge organization, and metadata semantic consistency in geological domain. This paper introduces ontology and integrates this theory to geological domain metadata modeling. It adopts the first order logic equivalent algorithm and defines the metadata extended model as a quaternion group which is consists of geological term set, geological term definition set, attribute definition set and instance set. It also provides the formal description of each set. Finally the five steps for building geological domain metadata extended model are given. The result presents that this model not only provides the content standards for geological domain knowledge representation and knowledge organization, but also provides the basis for geological domain multi-source data and historical data integration and application in semantic consistency.

Journal launch: Welcome Opto‐Electronic Science

Optics is an ancient and vibrant subject with a rich his-tory of thousands of years.Since Maxwell discovered that light is an electromagnetic wave,optics has always been accompanied by electricity.Optics and opto-electronics play a vital role in many key fields related to the devel-opment and progress of mankind,such as energy,infor-mation,internet,astronomy,and medicine,etc.Many large-scale scientific projects,ranging from laser nuclear fusion to gravitational wave detection,from large-aperture telescopes to lithography equipment,are mainly based on opto-electronic science.

纳光电子与光子芯片研究:发展与挑战

光子芯片被认为是“后摩尔时代”信息领域发展的核心技术之一。纳光电子学的发展为实现更高性能和更高集成度的光子芯片技术奠定了基础。同时,光子芯片对于突破电子芯片“卡脖子”的现实问题具有重要战略意义,有助于推动我国在未来光电信息产业的国际竞争中走出“缺芯”困境,并取得先发优势。基于国家自然科学基金委员会第312期“双清论坛”,本文总结了我国在纳光电子与光子芯片研究方面的重大需求,回顾了纳光电子与光子芯片领域近年来通过物理、材料、信息、制造等学科交叉融合所取得的主要进展和成就,凝炼了该领域未来5~10年的重大关键科学问题,探讨了前沿研究方向和科学基金资助战略。

Snapshot multi-dimensional computational imaging through a liquid crystal diffuser

Multi-dimensional optical imaging systems that simultaneously gather intensity,depth,polarimetric,and spectral information have numerous applications in medical sciences,robotics,and surveillance.Nevertheless,most current approaches require mechanical moving parts or multiple modulation processes and thus suffer from long acquisition time,high system complexity,or low sampling resolution.Here,a methodology to build snapshot multi-dimensional lensless imaging is proposed by combining planar-optics and computational technology,benefiting from sufficient flexibilities in optical engineering and robust information reconstructions.Specifically,a liquid crystal diffuser based on geometric phase modulation is designed to simultaneously encode the spatial,spectral,and polarization information of an object into a snapshot detected speckle pattern.At the same time,a post-processing algorithm acts as a special decoder to recover the hidden information in the speckle with the independent and unique point spread function related to the position,wavelength,and chirality.With the merits of snapshot acquisition,multi-dimensional perception ability,simple optical configuration,and compact device size,our approach can find broad potential applications in object recognition and classification.

Simultaneously enhancing capacity and security in free-space optical chaotic communication utilizing orbital angular momentum

Optical chaotic signals emitted from an external-cavity feedback or injected laser diode enable small-signal information concealment in a noise-like carrier for secure optical communications.Due to the chaotic bandwidth limitation resulting from intrinsic relaxation oscillation frequency of lasers,multiplexing of optical chaotic signal,such as wavelength division multiplexing in fiber,is a typical candidate for high-capacity secure applications.However,to our best knowledge,the utilization of the spatial dimension of optical chaos for free-space secure communication has not yet been reported.Here,we experimentally demonstrate a free-space all-optical chaotic communication system that simultaneously enhances transmission capacity and security by orbital angular momentum(OAM)multiplexing.Optical chaotic signals with two different OAM modes totally carrying 20 Gbps on-off keying signals are secretly transmitted over a 2 m free-space link,where the channel crosstalk of OAM modes is less than-20 d B,with the mode spacing no less than 3.The receiver can extract valid information only when capturing approximately 92.5% of the OAM beam and correctly demodulating the corresponding mode.Bit error rate below the 7%hard-decision forward error correction threshold of 3.8×10^(-3)can be achieved for the intended recipient.Moreover,a simulated weak turbulence is introduced to comprehensively analyze the influence on the system performance,including channel crosstalk,chaotic synchronization,and transmission performance.Our work may inspire structured light application in optical chaos and pave a new way for developing future high-capacity free-space chaotic secure communication systems.

High-precision fabrication of 4m SiC aspheric mirror

The 4 m diameter SiC aspheric mirror emerges due to a series of technological breakthroughs in blank mirror preparation,asphere fabrication,and testing,as well as cladding and coating,laying the groundwork for future research into large SiC mirrors for astronomical observation.

Design and fabrication of broadband ultralow reflectivity black Si surfaces by laser micro/nanoprocessing

Light collection efficiency is an important factor that affects the performance of many optical and optoelectronic devices.In these devices,the high reflectivity of interfaces can hinder efficient light collection.To minimize unwanted reflection,anti-reflection surfaces can be fabricated by micro/nanopatterning.In this paper,we investigate the fabrication of broadband anti-reflection Si surfaces by laser micro/nanoprocessing.Laser direct writing is applied to create microstructures on Si surfaces that reduce light reflection by light trapping.In addition,laser interference lithography and metal assisted chemical etching are adopted to fabricate the Si nanowire arrays.The anti-reflection performance is greatly improved by the high aspect ratio subwavelength structures,which create gradients of refractive index from the ambient air to the substrate.Furthermore,by decoration of the Si nanowires with metallic nanoparticles,surface plasmon resonance can be used to further control the broadband reflections,reducing the reflection to below 1.0%across from 300 to 1200 nm.An average reflection of 0.8%is achieved.

Spin-decoupled metasurface for simultaneous detection of spin and orbital angular momenta via momentum transformation

With inherent orthogonality,both the spin angular momentum(SAM)and orbital angular momentum(OAM)of photons have been utilized to expand the dimensions of quantum information,optical communications,and information processing,wherein simultaneous detection of SAMs and OAMs with a single element and a single-shot measurement is highly anticipated.Here,a single azimuthal-quadratic phase metasurface-based photonic momentum transformation(PMT)is illustrated and utilized for vortex recognition.Since different vortices are converted into focusing patterns with distinct azimuthal coordinates on a transverse plane through PMT,OAMs within a large mode space can be determined through a single-shot measurement.Moreover,spin-controlled dual-functional PMTs are proposed for simultaneous SAM and OAM sorting,which is implemented by a single spin-decoupled metasurface that merges both the geometric phase and dynamic phase.Interestingly,our proposed method can detect vectorial vortices with both phase and polarization singularities,as well as superimposed vortices with a certain interval step.Experimental results obtained at several wavelengths in the visible band exhibit good agreement with the numerical modeling.With the merits of ultracompact device size,simple optical configuration,and prominent vortex recognition ability,our approach may underpin the development of integrated and high-dimensional optical and quantum systems.