教育、科技、人才一体布局与科学基金发展战略

教育、科技、人才一体布局的统筹部署已经成为全面建设社会主义现代化国家的基础性、战略性支撑,深刻理解与把握教育、科技、人才一体布局重大意义对开展基础研究资助至关重要。在厘清一体布局对基础研究资助新要求的前提下,明确基础研究资助在科学研究、科学教育与人才培养有机结合中的定位和作用,完善国家自然科学基金资助管理体系,探索落实一体布局的着力点,从而提出新时代科学基金发展的战略思路,为教育强国、科技强国、人才强国建设提供源头支撑。

Multi-dimensional multiplexing optical secret sharing framework with cascaded liquid crystal holograms

Secret sharing is a promising technology for information encryption by splitting the secret information into different shares.However,the traditional scheme suffers from information leakage in decryption process since the amount of available information channels is limited.Herein,we propose and demonstrate an optical secret sharing framework based on the multi-dimensional multiplexing liquid crystal(LC)holograms.The LC holograms are used as spatially separated shares to carry secret images.The polarization of the incident light and the distance between different shares are served as secret keys,which can significantly improve the information security and capacity.Besides,the decryption condition is also restricted by the applied external voltage due to the variant diffraction efficiency,which further increases the information security.In implementation,an artificial neural network(ANN)model is developed to carefully design the phase distribution of each LC hologram.With the advantage of high security,high capacity and simple configuration,our optical secret sharing framework has great potentials in optical encryption and dynamic holographic display.

A Generic Strategy to Create Mechanically Interlocked Nanocomposite/Hydrogel Hybrid Electrodes for Epidermal Electronics

Stretchable electronics are crucial enablers for next-generation wearables intimately integrated into the human body.As the primary compliant conductors used in these devices,metallic nanostructure/elastomer composites often struggle to form conformal contact with the textured skin.Hybrid electrodes have been consequently developed based on conductive nanocomposite and soft hydrogels to establish seamless skin-device interfaces.However,chemical modifications are typically needed for reliable bonding,which can alter their original properties.To overcome this limitation,this study presents a facile fabrication approach for mechanically interlocked nanocomposite/hydrogel hybrid electrodes.In this physical process,soft microfoams are thermally laminated on silver nanowire nanocomposites as a porous interface,which forms an interpenetrating network with the hydrogel.The microfoam-enabled bonding strategy is generally compatible with various polymers.The resulting interlocked hybrids have a 28-fold improved interfacial toughness compared to directly stacked hybrids.These electrodes achieve firm attachment to the skin and low contact impedance using tissue-adhesive hydrogels.They have been successfully integrated into an epidermal sleeve to distinguish hand gestures by sensing mus-cle contractions.Interlocked nanocomposite/hydrogel hybrids reported here offer a promising platform to combine the benefits of both materials for epidermal devices and systems.

Optical scanning endoscope via a single multimode optical fiber

Optical endoscopy has become an essential diagnostic and therapeutic approach in modern biomedicine for directly observing organs and tissues deep inside the human body,enabling non-invasive,rapid diagnosis and treatment.Optical fiber endoscopy is highly competitive among various endoscopic imaging techniques due to its high flexibility,compact structure,excellent resolution,and resistance to electromagnetic interference.Over the past decade,endoscopes based on a single multimode optical fiber(MMF)have attracted widespread research interest due to their potential to significantly reduce the footprint of optical fiber endoscopes and enhance imaging capabilities.In comparison with other imaging principles of MMF endoscopes,the scanning imaging method based on the wavefront shaping technique is highly developed and provides benefits including excellent imaging contrast,broad applicability to complex imaging scenarios,and good compatibility with various well-established scanning imaging modalities.In this review,various technical routes to achieve light focusing through MMF and procedures to conduct the scanning imaging of MMF endoscopes are introduced.The advancements in imaging performance enhancements,integrations of various imaging modalities with MMF scanning endoscopes,and applications are summarized.Challenges specific to this endoscopic imaging technology are analyzed,and potential remedies and avenues for future developments are discussed.

Liquid crystal droplets formation and stabilization during phase transition process

The study of phase transition processes in liquid crystals(LCs)remains challenging.Most thermotropic LCs exhibit a narrow temperature range and a rapid phase transition from the isotropic(ISO)to the nematic(N)phase,which make it difficult to capture and manipulate the phase transition process.In this study,we observed the evolution of small droplets during the ISO–N phase transition in ferroelectric nematic(NF)LC RM734.After doping with metal nanoparticles(NPs),the temperature range of the phase transition broadened,and the droplets formed during the phase transition remained stable,with their diameter increasing linearly with temperature.In addition,droplets doped with NPs can be well controlled by an external electric field.This discovery not only aids in understanding the fundamental mechanisms of LC phase transitions but also provides a simple alternative method for preparing droplets,which is potentially valuable for applications in optoelectronic devices and sensors.

Seeing at a distance with multicore fibers

Images and videos provide a wealth of information for people in production and life.Although most digital information is transmitted via optical fiber,the image acquisition and transmission processes still rely heavily on electronic circuits.The development of all-optical transmission networks and optical computing frameworks has pointed to the direction for the next generation of data transmission and information processing.Here,we propose a high-speed,low-cost,multiplexed parallel and one-piece all-fiber architecture for image acquisition,encoding,and transmission,called the Multicore Fiber Acquisition and Transmission Image System(MFAT).Based on different spatial and modal channels of the multicore fiber,fiber-coupled self-encoding,and digital aperture decoding technology,scenes can be observed directly from up to 1 km away.The expansion of capacity provides the possibility of parallel coded transmission of multimodal high-quality data.MFAT requires no additional signal transmitting and receiving equipment.The all-fiber processing saves the time traditionally spent on signal conversion and image pre-processing(compression,encoding,and modulation).Additionally,it provides an effective solution for 2D information acquisition and transmission tasks in extreme environments such as high temperatures and electromagnetic interference.

Spatiotemporal hemodynamic monitoring via configurable skin-like microfiber Bragg grating group

Systemic blood circulation is one of life activity’s most important physiological functions.Continuous noninvasive hemodynamicmonitoring is essential for the management of cardiovascular status.However,it is difficult to achieve systemichemodynamic monitoring with the daily use of current devices due to the lack of multichannel and time-synchronized operationcapability over the whole body.Here,we utilize a soft microfiber Bragg grating group to monitor spatiotemporalhemodynamics by taking advantage of the high sensitivity,electromagnetic immunity,and great temporal synchronizationbetween multiple remote sensor nodes.A continuous systemic hemodynamic measurement technique is developedusing all-mechanical physiological signals,such as ballistocardiogram signals and pulse waves,to illustrate the actualmechanical process of blood circulation.Multiple hemodynamic parameters,such as systemic pulse transit time,heartrate,blood pressure,and peripheral resistance,are monitored using skin-like microfiber Bragg grating patches conformallyattached at different body locations.Relying on the soft microfiber Bragg grating group,the spatiotemporal hemodynamicmonitoring technique opens up new possibilities in clinical medical diagnosis and daily health management.

Janus aramid nanofiber aerogel incorporating plasmonic nanoparticles for high-efficiency interfacial solar steam generation

Interfacial solar steam generation(ISSG)is a novel and potential solution to global freshwater crisis.Here,based on a facile sol-gel fabrication process,we demonstrate a highly scalable Janus aramid nanofiber aerogel(JANA)as a high-efficiency ISSG device.JANA performs near-perfect broadband optical absorption,rapid photothermal conversion and effective water transportation.Owning to these features,efficient desalination of salty water and purification of municipal sewage are successfully demonstrated using JANA.In addition,benefiting from the mechanical property and chemical stability of constituent aramid nanofibers,JANA not only possesses outstanding flexibility and fire-resistance properties,but its solar steaming efficiency is also free from the influences of elastic deformations and fire treatments.We envision JANA provides a promising platform for mass-production of high-efficiency ISSG devices with supplementary capabilities of convenient transportation and long-term storage,which could further promote the realistic applications of ISSG technology.

Label-free fiber nanograting sensor for real-time in situ early monitoring of cellular apoptosis

The achievement of functional nanomodules for subcellular label-free measurement has long been pursued in order to fully understand cellular functions.Here,a compact label-free nanosensor based on a fiber taper and zinc oxide nanogratings is designed and applied for the early monitoring of apoptosis in individual living cells.Because of its nanoscale dimensions,mechanical flexibility,and minimal cytotoxicity to cells,the sensing module can be loaded in cells for long term in situ tracking with high sensitivity.A gradual increase in the nuclear refractive index during the apoptosis process is observed,revealing the increase in molecular density and the decrease in cell volume.The strategy used in our study not only contributes to the understanding of internal environmental variations during cellular apoptosis but also provides a new platform for nonfluorescent fiber devices for investigation of cellular events and understanding fundamental cell biochemical engineering.

统一大市场建设中如何谋求“央地同心”?——基于多元主体演化博弈视角

在全国统一大市场建设背景下,“央地同心”是实现统一大市场建设目标的关键,但当前部分地方政府仍缺乏建设统一大市场的积极性,地区市场分割问题依然存在。对此,本文构建了包含中央政府与两个地方政府的三方演化博弈模型,分析了达成良性协同策略的均衡条件,以长三角地区的案例为基础进行了敏感性分析,探究了政府行为选择的演化趋势和影响因素,并进一步对政府行为选择的内生逻辑进行归纳。本文的主要结论包括:当多方利益未完全达成一致时,地方政府间关联性行为将有可能导致政策执行出现异化;地方政府收益是中央政府实现对地方政府行为激励的关键切入点。本文提出的主要对策包括:充分保障统一大市场建设进程中各地方政府效益;不断加深统一大市场的建设力度;合理利用相关诱因来调动地方政府政策执行的积极性。

Metasurface-based computational imaging:a review

Metasurface-based imaging has attracted considerable attention owing to its compactness,multifunctionality,and subwavelength coding capability.With the integration of computational imaging techniques,researchers have actively explored the extended capabilities of metasurfaces,enabling a wide range of imaging methods.We present an overview of the recent progress in metasurface-based imaging techniques,focusing on the perspective of computational imaging.Specifically,we categorize and review existing metasurface-based imaging into three main groups,including(i)conventional metasurface design employing canonical methods,(ii)computation introduced independently in either the imaging process or postprocessing,and(iii)an end-to-end computation-optimized imaging system based upon metasurfaces.We highlight the advantages and challenges associated with each computational metasurface-based imaging technique and discuss the potential and future prospects of the computational boosted metaimager.

Optical properties of stacked liquid crystal superstructures with opposite chirality [Invited]

Cholesteric liquid crystal (CLC) has been widely used in flat optical elements due to the Pancharatnam–Berry(PB) phase modulation. In order to achieve PB phase modulation for both circular polarizations, it is natural to come up with stacking CLCs with opposite chirality. Here, various optical properties of diverse CLC stacking structures are systematically investigated by numerical calculations. With the thickness of the CLC sublayers becoming smaller, the reflection bandgap splits into three main parts, and the rotatory dispersion gradually becomes negligible. Vector beams provide a more intuitive verification. These results provide theoretical guidance for future studies on stacked chiral anisotropic media.

Quantifying trapping stability of optical tweezers with an external flow

Optical tweezers(OTs)can immobilize and manipulate objects with sizes that span between nano-and micrometer scales.The manipulating ability of OTs is traditionally characterized by stability factor(S),which can only indicate an empirical“hit-or-miss”process.Additionally,the current quantitative models for trapping stability rarely consider the influence of external flow.In this paper,a comprehensive analysis to quantify the optical trapping stability in a perturbed asymmetric potential well is presented from the perspective of statistics,especially for weak trapping scenarios.Our analytical formulation takes experimentally measurable parameters including particle size,optical power,and spot width as inputs and precisely outputs a statistically relevant mean trapping time.Importantly,this formulation takes into account general and realistic cases including fluidic flow velocity and other perturbations.To verify the model,a back-focal-plane-interferometer-monitored trapping experiment in a flow is set up and the statistical characteristics of trapping time demonstrate good agreement with theoretical predictions.In total,the model quantitatively reveals the effects of external disturbance on trapping time,which will find applications where optical trapping stability is challenged by external perturbations in weak trapping conditions.

Low-loss metasurface optics down to the deep ultraviolet region

Shrinking conventional optical systems to chip-scale dimensions will benefit custom applications in imaging,displaying,sensing,spectroscopy,and metrology.Towards this goal,metasurfaces-planar arrays of subwavelength electromagnetic structures that collectively mimic the functionality of thicker conventional optical elements-have been exploited at frequencies ranging from the microwave range up to the visible range.Here,we demonstrate highperformance metasurface optical components that operate at ultraviolet wavelengths,including wavelengths down to the record-short deep ultraviolet range,and perform representative wavefront shaping functions,namely,highnumerical-aperture lensing,accelerating beam generation,and hologram projection.The constituent nanostructured elements of the metasurfaces are formed of hafnium oxide-a loss-less,high-refractive-index dielectric material deposited using low-temperature atomic layer deposition and patterned using high-aspect-ratio Damascene lithography.This study opens the way towards low-form factor,multifunctional ultraviolet nanophotonic platforms based on flat optical components,enabling diverse applications including lithography,imaging,spectroscopy,and quantum information processing.

Multifunctional metasurfaces enabled by simultaneous and independent control of phase and amplitude for orthogonal polarization states

Monochromatic light can be characterized by its three fun dame ntal properties:amplitude,phase,and polarization.In this work,we propose a versatile,transmission-mode all-dielectric metasurface platform that can independently manipulate the phase and amplitude for two orthogonal states of polarization in the visible frequency range.For proof-o仁concept experimental demonstration,various single-layer metasurfaces composed of subwavelength-spaced titanium-dioxide nanopillars are designed,fabricated,and characterized to exhibit the ability of polarization-switchable multidimensional light-field manipulation,including polarization-switchable grayscale nanoprinting,nonuniform cylindrical lensing,and complex-amplitude holography.We envision the metasurface platform dem on strated here to open new possibilities toward creating compact multifunctional optical devices for applications in polarization optics,information encoding,optical data storage,and security.

Biomimetic Corrugated Silicon Nanocone Arrays for Self-Cleaning Antireflection Coatings

Corrugated silicon nanocone(SiNC)arrays have been fabricated on a silicon wafer by two polystyrene-sphere-monolayer-masked etching steps in order to create high-performance antireflective coatings.The reflectance was reduced from above 35%to less than 0.7%in the range 400-1050 nm,and it remained below 0.5%at incidence angles up to 70°at 632.8 nm for both s-and p-polarized light.The fluorinated corrugated SiNC array surface exhibits superhydrophobic properties with a water contact angle of 164°.

Highly effective and reproducible surface-enhanced Raman scattering substrates based on Ag pyramidal arrays

Close-packed Ag pyramidal arrays have been fabricated by using inverted pyramidal pits on Si as a template and used to generate plentiful and homogeneous surface-enhanced Raman scattering （SERS） hot sites. The sharp nanotip and the four edges of the Ag pyramid result in strong electromagnetic field enhancement with an average enhancement factor （EF） of 2.84 × 10^7. Moreover, the features of the close-packed Ag pyramidal array can be well controlled, which allows SERS substrates with good reproducibility to be obtained. The relative standard deviation （RSD） was lower than 8.78% both across a single substrate and different batches of substrates.

Liquid crystal integrated metalens with tunable chromatic aberration

Overcoming chromatic aberrations is a vital concern in imaging systems in order to facilitate fullcolor and hyperspectral imaging.By contrast,large dispersion holds opportunities for spectroscopy and tomography.Combining both functions into a single component will significantly enhance its versatility.A strategy is proposed to delicately integrate two lenses with a static resonant phase and a switchable geometric phase separately.The former is a metasurface lens with a linear phase dispersion.The latter is composed of liquid crystals(LCs)with space-variant orientations with a phase profile that is frequency independent.By this means,a broadband achromatic focusing from 0.9 to 1.4 THz is revealed.When a saturated bias is applied on LCs,the geometric phase modulation vanishes,leaving only the resonant phase of the metalens.Correspondingly,the device changes from achromatic to dispersive.Furthermore,a metadeflector with tunable dispersion is demonstrated to verify the universality of the proposed method.Our work may pave a way toward active metaoptics,promoting various imaging applications.

Dual-color terahertz spatial light modulator for single-pixel imaging

Spatial light modulators(SLM),capable of dynamically and spatially manipulating electromagnetic waves,have reshaped modern life in projection display and remote sensing.The progress of SLM will expedite next-generation communication and biomedical imaging in the terahertz(THz)range.However,most current THz SLMs are adapted from optical alternatives that still need improvement in terms of uniformity,speed,and bandwidth.Here,we designed,fabricated,and characterized an 8×8THz SLM based on tunable liquid crystal metamaterial absorbers for THz single-pixel compressive imaging.We demonstrated dual-color compressive sensing(CS)imaging for dispersive objects utilizing the large frequency shift controlled by an external electric field.We developed auto-calibrated compressive sensing(ACS)algorithm to mitigate the impact of the spatially nonuniform THz incident beam and pixel modulation,which significantly improves the fidelity of reconstructed images.Furthermore,the complementary modulation at two absorption frequencies enables Hadamard masks with negative element values to be realized by frequency-switching,thereby halving the imaging time.The demonstrated imaging system paves a new route for THz single-pixel multispectral imaging with high reliability and low cost.

Tunable terahertz absorber based on transparent and flexible metamaterial

We demonstrate a tunable terahertz(THz) absorber based on an indium tin oxide(ITO) metamaterial. The upper ITO cross-shaped metasurface with different arm lengths is fabricated by direct femtosecond laser etching.The thickness of the middle dielectric layer is only 60 μm, which makes the absorber very transparent and flexible. The experimental results show that the THz resonant peaks have a high performance near 1 THz. By setting spacers of different thicknesses between the middle layer and the ITO mirror, a new type of tunable THz absorber is proposed. Its absorption peak frequency can be continuously adjusted from 0.92 to 1.04 THz between TE and TM polarization. This transparent THz metamaterial absorber is expected to be widely used in THz imaging, sensing, and biological detection.