Manufacturing-robust imaging systems leveraging computational optics hold immense potential for easing manufacturing constraints and enabling the development of cost-effective,high-quality imaging solutions.However,co...Manufacturing-robust imaging systems leveraging computational optics hold immense potential for easing manufacturing constraints and enabling the development of cost-effective,high-quality imaging solutions.However,conventional approaches,which typically rely on data-driven neural networks to correct optical aberrations caused by manufacturing errors,are constrained by the lack of effective tolerance analysis methods for quantitatively evaluating manufacturing error boundaries.This limitation is crucial for further relaxing manufacturing constraints and providing practical guidance for fabrication.We propose a physics-informed design paradigm for manufacturing-robust imaging systems with computational optics,integrating a physics-informed tolerance analysis methodology for evaluating manufacturing error boundaries and a physics-informed neural network for image reconstruction.With this approach,we achieve a manufacturing-robust imaging system based on an off-axis three-mirror freeform all-aluminum design,delivering a modulation transfer function exceeding 0.34 at the Nyquist frequency(72 lp/mm)in simulation.Notably,this system requires a manufacturing precision of only 0.5λin root mean square(RMS),representing a remarkable 25-fold relaxation compared with the conventional requirement of 0.02λin RMS.Experimental validation further confirmed that the manufacturing-robust imaging system maintains excellent performance in diverse indoor and outdoor environments.Our proposed method paves the way for achieving high-quality imaging without the necessity of high manufacturing precision,enabling practical solutions that are more cost-effective and time-efficient.展开更多
Traceability is the fundamental premise of all metrological activities. The establishment of a traceability chain characterized by a shortened structure, while simultaneously enabling on-site traceability, represents ...Traceability is the fundamental premise of all metrological activities. The establishment of a traceability chain characterized by a shortened structure, while simultaneously enabling on-site traceability, represents a key trend in the advancement of metrology. This study explores the periodic accuracy and overall uniformity of self-traceable gratings, employing multilayer film gratings with a nominal period of 25.00 nm as the medium. We present a comparative analysis of measurement capabilities in a self-traceable grating calibration system characterized by a ‘top-down’ calibration approach and a Si lattice constant calibration system characterized by a ‘bottom-up’ calibration approach. The results indicate that the values obtained for the multilayer film grating periods, calibrated using the self-traceable grating system, are 24.40 nm with a standard deviation of 0.11 nm. By comparing with the values derived from the Si lattice constant, which yield 24.34 nm with a standard deviation of 0.14 nm, the validity and feasibility of the self-traceable calibration system are confirmed. This system extends and complements existing metrological frameworks, offering a precise pathway for traceability in precision engineering and nanotechnology research.展开更多
Developing highly accurate critical dimension standards is a significant task for nanoscale metrology. In this paper, we put forward an alternative approach to fabricate amorphous Si critical dimension structures with...Developing highly accurate critical dimension standards is a significant task for nanoscale metrology. In this paper, we put forward an alternative approach to fabricate amorphous Si critical dimension structures with direct Si lattice calibration in the same frame scanning transmission electron microscopy image. Based on the traceable measurement analysis, the optimized method can provide the same calibration accuracy and increase the fabrication throughput and lower the cost simultaneously, which benefits the application needs in atomic force microscopy(AFM) tip geometry characterization,benchmarking measurement tools, and conducting comparison measurements between different approaches.展开更多
The line width(often synonymously used for critical dimension,CD)is a crucial parameter in integrated circuits.To accurately control CD values in manufacturing,a reasonable CD reference material is required to calibra...The line width(often synonymously used for critical dimension,CD)is a crucial parameter in integrated circuits.To accurately control CD values in manufacturing,a reasonable CD reference material is required to calibrate the corresponding instruments.We develop a new reference material with nominal CDs of 160 nm,80 nm,and 40 nm.The line features are investigated based on the metrological scanning electron microscope which is developed by the National Institute of Metrology(NIM)in China.Also,we propose a new characterization method for the precise measurement of CD values.After filtering and leveling the intensity profiles,the line features are characterized by the combination model of the Gaussian and Lorentz functions.The left and right edges of CD are automatically extracted with the profile decomposition and k-means algorithm.Then the width of the two edges at the half intensity position is regarded as the standard CD value.Finally,the measurement results are evaluated in terms of the sample,instrument,algorithm,and repeatability.The experiments indicate efficiency of the proposed method which can be easily applied in practice to accurately characterize CDs.展开更多
Design of multiple-feed lens antennas requires multivariate and multi-objective optimization processes,which can be accelerated by PSO algorithms.However,the PSO algorithm often fails to achieve optimal results with l...Design of multiple-feed lens antennas requires multivariate and multi-objective optimization processes,which can be accelerated by PSO algorithms.However,the PSO algorithm often fails to achieve optimal results with limited computation resources since spaces of candidate solutions are quite large for lens antenna designs.This paper presents a design paradigm for multiple-feed lens antennas based on a physics-assisted particle swarm optimization(PA-PSO)algorithm,which guides the swarm of particles based on laws of physics.As a proof of concept,a design of compact metalens antenna is proposed,which measures unprecedented performances,such as a field of view at±55°,a 21.7 dBi gain with a flatness within 4 dB,a 3-dB bandwidth>12°,and a compact design with a f-number of 0.2.The proposed PA-PSO algorithm reaches the optimal results 6 times faster than the ordinary PSO algorithm,which endows promising applications in the multivariate and multi-objective optimization processes,including but not limited to metalens antenna designs.展开更多
Laser focused atomic deposition is a unique and effective way to fabricate highly accurate pitch standards in nanometrology.However,the stability and repeatability of the atom lithography fabrication process remains a...Laser focused atomic deposition is a unique and effective way to fabricate highly accurate pitch standards in nanometrology.However,the stability and repeatability of the atom lithography fabrication process remains a challenging problem for massive production.Based on the atom-light interaction theory,channeling is utilized to improve the stability and repeatability.From the comparison of three kinds of atom-light interaction models,the optimal parameters for channeling are obtained based on simulation.According to the experimental observations,the peak to valley height of Cr nano-gratings keeps stable when the cutting proportion changes from 15%to 50%,which means that the channeling shows up under this condition.The channeling proves to be an effective method to optimize the stability and repeatability of laser focused Cr atomic deposition.展开更多
An approach for studying the influence of nano-particles on the structural properties of deposited thin films is proposed. It is based on the molecular dynamic modeling of the deposition process in the presence of con...An approach for studying the influence of nano-particles on the structural properties of deposited thin films is proposed. It is based on the molecular dynamic modeling of the deposition process in the presence of contaminating nano-particles. The nano-particle is assumed to be immobile and its interaction with film atoms is described by a spherically symmetric potential. The approach is applied to the investigation of properties of silicon dioxide films. Visualization tools are used to investigate the porosity associated with nano-particles. The structure of the film near the nano-particle is studied using the radial distribution function. It is found that fluctuations of film density near the nano-particles are essentially different in the cases of low-energy and high-energy deposition processes.展开更多
Optical sorting combines optical tweezers with diverse techniques,including optical spectrum,artificial intelligence(AI)and immunoassay,to endow unprecedented capabilities in particle sorting.In comparison to other me...Optical sorting combines optical tweezers with diverse techniques,including optical spectrum,artificial intelligence(AI)and immunoassay,to endow unprecedented capabilities in particle sorting.In comparison to other methods such as microfluidics,acoustics and electrophoresis,optical sorting offers appreciable advantages in nanoscale precision,high resolution,non-invasiveness,and is becoming increasingly indispensable in fields of biophysics,chemistry,and materials science.This review aims to offer a comprehensive overview of the history,development,and perspectives of various optical sorting techniques,categorised as passive and active sorting methods.To begin,we elucidate the fundamental physics and attributes of both conventional and exotic optical forces.We then explore sorting capabilities of active optical sorting,which fuses optical tweezers with a diversity of techniques,including Raman spectroscopy and machine learning.Afterwards,we reveal the essential roles played by deterministic light fields,configured with lens systems or metasurfaces,in the passive sorting of particles based on their varying sizes and shapes,sorting resolutions and speeds.We conclude with our vision of the most promising and futuristic directions,including AI-facilitated ultrafast and bio-morphology-selective sorting.It can be envisioned that optical sorting will inevitably become a revolutionary tool in scientific research and practical biomedical applications.展开更多
Accurately and swiftly characterizing the state of polarization(SoP)of complex structured light is crucial in the realms of classical and quantum optics.Conventional strategies for detecting SoP,which typically involv...Accurately and swiftly characterizing the state of polarization(SoP)of complex structured light is crucial in the realms of classical and quantum optics.Conventional strategies for detecting SoP,which typically involves a sequence of cascaded optical elements,are bulky,complex,and run counter to miniaturization and integration.While metasurfaceenabled polarimetry has emerged to overcome these limitations,its functionality predominantly remains confined to identifying SoP within the standard Poincare sphere framework.The comprehensive detection of SoP on the higherorder Poincare sphere(HOPS),however,continues to be a huge challenge.Here,we propose a general polarization metrology method capable of fully detecting SoP on any HOPS through a single measurement.The underlying mechanism relies on transforming the optical singularities and Stokes parameters into visualized intensity patterns,facilitating the extraction of all parameters that fully determine a SoP.We actualize this concept through a novel metadevice known as the metasurface photonics polarization clock,which offers an intuitive display of SoP using four distinct pointers.As a proof of concept,we theoretically and experimentally demonstrate fully resolving SoPs on the Oth,1st,and 2nd HOPSs.Our implementation opens up a new pathway towards real-time polarimetry of arbitrary beams featuring miniaturized size,a simple detection process,and a direct readout mechanism,promising significant advancements in fields reliant on polarization.展开更多
Circular dichroism(CD)spectroscopy,widely used for chiral sensing,has been limited by the detection sensitivity.Enhancing optical chirality in the light fields interacting with chiral molecules is crucial for achievin...Circular dichroism(CD)spectroscopy,widely used for chiral sensing,has been limited by the detection sensitivity.Enhancing optical chirality in the light fields interacting with chiral molecules is crucial for achieving ultrasensitive chiral detection.Here,we present a new paradigm for ultrasensitive chiral detection by creating accessible chiral hotspots using a toroidal dipole Fabry–Perot bound state in the continuum(TD FP-BIC)metasurface.BIC resonance is achieved by controlling the coupling between the TD resonance and its multilayer reflector-induced perfect mirror image.This method enables unprecedented local maximum and average optical chirality enhancements of up to 6×10^(4)-fold and 2×10^(3)-fold,respectively,within non-structured regions,resulting in an 866-fold increase in CD signals compared to chiral molecules alone without nanostructures.Our results pave the way for enhanced light–matter interactions and ultrasensitive enantiomeric operation.展开更多
Replacing electrons with photons is a compelling route toward high-speed,massively parallel,and low-power artificial intelligence computing.Recently,diffractive networks composed of phase surfaces were trained to perf...Replacing electrons with photons is a compelling route toward high-speed,massively parallel,and low-power artificial intelligence computing.Recently,diffractive networks composed of phase surfaces were trained to perform machine learning tasks through linear optical transformations.However,the existing architectures often comprise bulky components and,most critically,they cannot mimic the human brain for multitasking.Here,we demonstrate a multi-skilled diffractive neural network based on a metasurface device,which can perform on-chip multi-channel sensing and multitasking in the visible.The polarization multiplexing scheme of the subwavelength nanostructures is applied to construct a multi-channel classifier framework for simultaneous recognition of digital and fashionable items.The areal density of the artificial neurons can reach up to 6.25×10^(6)mm^(-2) multiplied by the number of channels.The metasurface is integrated with the mature complementary metal-oxide semiconductor imaging sensor,providing a chip-scale architecture to process information directly at physical layers for energy-efficient and ultra-fast image processing in machine vision,autonomous driving,and precision medicine.展开更多
Thermomechanical damage of nodules in dielectric multilayer coatings that are irradiated by nanosecond laser pulses has been interpreted with respect to mechanical properties and electric-field enhancement.However,the...Thermomechanical damage of nodules in dielectric multilayer coatings that are irradiated by nanosecond laser pulses has been interpreted with respect to mechanical properties and electric-field enhancement.However,the effect of electric-field enhancement in nodular damage,especially the influence of electric-field distributions,has never been directly demonstrated through experimental results,which prevents the achievement of a clear understanding of the damage process of nodular defects.Here,a systematic and comparative study was designed to reveal how electric-field distributions affect the damage behavior of nodules.To obtain reliable results,two series of artificial nodules with different geometries and film absorption characteristics were prepared from monodisperse silica microspheres.After establishing simplified geometrical models of the nodules,the electric-field enhancement was simulated using a three-dimensional finite-difference time-domain code.Then,the damage morphologies of the artificial nodules were directly compared with the simulated electric-field intensity profiles.For both series of nodules,the damage morphologies reproduced our simulated electric-field intensity distributions very well.These results indicated that the electric-field distribution was actually a bridge that connected the nodular mechanical properties to the final thermomechanical damage.Understanding of the damage mechanism of nodules was deepened by obtaining data on the influence of electric-field distributions on the damage behavior of nodules.展开更多
Exceptional point (EP) is a special degeneracy of non-Hermitian systems. One-dimensional transmission systems operating at EPs are widely studied and applied to chiral conversion and sensing. Lately, two-dimensional s...Exceptional point (EP) is a special degeneracy of non-Hermitian systems. One-dimensional transmission systems operating at EPs are widely studied and applied to chiral conversion and sensing. Lately, two-dimensional systems at EPs have been exploited for their exotic scattering features, yet so far been limited to only the non-visible waveband. Here, we report a universal paradigm for achieving a high-efficiency EP in the visible by leveraging interlayer loss to accurately control the interplay between the lossy structure and scattering lightwaves. A bilayer framework is demonstrated to reflect back the incident light from the left side ( | r_(−1) | >0.999) and absorb the incident light from the right side ( | r_(+1) | < 10^(–4)). As a proof of concept, a bilayer metasurface is demonstrated to reflect and absorb the incident light with experimental efficiencies of 88% and 85%, respectively, at 532 nm. Our results open the way for a new class of nanoscale devices and power up new opportunities for EP physics.展开更多
Double-layer high-contrast subwavelength gratings that are separated by a dielectric space layer are investigated to achieve ultra-broadband reflection.The reflection phase of subwavelength gratings and the propagatio...Double-layer high-contrast subwavelength gratings that are separated by a dielectric space layer are investigated to achieve ultra-broadband reflection.The reflection phase of subwavelength gratings and the propagation phase shift between two gratings are manipulated to expand reflection bandwidth by properly stacking two reflective gratings.A reflector exhibiting a 99%reflectance bandwidth of^1080 nm in the near-infrared is designed.Then this reflector is prepared using laser interference lithography and ion beam planarization,and an ultra-broadband reflection is achieved with reflectance exceeding 97%over a wavelength range of 955 nm in the near-infrared region.展开更多
Atom lithography is a unique method to fabricate self-traceable pitch standards and angle standards,but extending its structure area to millimeter-level for application is challenging.In this paper,on the one hand,we ...Atom lithography is a unique method to fabricate self-traceable pitch standards and angle standards,but extending its structure area to millimeter-level for application is challenging.In this paper,on the one hand,we put forward a new approach to fabricate a full-covered self-traceable Cr nanograting by inserting and scanning a Dove prism in the Gaussian beam direction of atom lithography.On the other hand,we extend the structure area along the standing-wave direction by splicing two-step atom deposition.Both nanostructures manufactured via scanning atom lithography and splicing atom lithography demonstrate good pitch accuracy,parallelism,continuity,and homogeneity,which opens a new way to fabricate centimeter-level full-covered self-traceable nanograting and lays the basis for the application of square ruler and optical encoders at the nanoscale.展开更多
The influence of nodule defects on the characteristics of femtosecond laser-induced damage has not been fully investigated.In this study,two types of 800 nm/1064 nm dual-band HfO_(2)=Si O_(2) high-reflection films wit...The influence of nodule defects on the characteristics of femtosecond laser-induced damage has not been fully investigated.In this study,two types of 800 nm/1064 nm dual-band HfO_(2)=Si O_(2) high-reflection films with different configurations were analyzed.Combined with finite-difference time-domain electric field simulation and focused ion beam analysis,the initial state and growth process of femtosecond laser damage of nodules were explored.In particular,the sequence of blister damage determined by the film design and the inner damage caused by nodules were clarified.The rule of the laser-induced damage threshold of different size nodules was obtained.The difference in the damage behavior of nodules in the two types of films was elucidated.展开更多
Inferring the properties of a scattering objective by analyzing the optical far-field responses within the framework of inverse problems is of great practical significance.However,it still faces major challenges when ...Inferring the properties of a scattering objective by analyzing the optical far-field responses within the framework of inverse problems is of great practical significance.However,it still faces major challenges when the parameter range is growing and involves inevitable experimental noises.Here,we propose a solving strategy containing robust neuralnetworks-based algorithms and informative photonic dispersions to overcome such challenges for a sort of inverse scattering problem—reconstructing grating profiles.Using two typical neural networks,forward-mapping type and inverse-mapping type,we reconstruct grating profiles whose geometric features span hundreds of nanometers with nanometric sensitivity and several seconds of time consumption.A forward-mapping neural network with a parameters-to-point architecture especially stands out in generating analytical photonic dispersions accurately,featured by sharp Fano-shaped spectra.Meanwhile,to implement the strategy experimentally,a Fourier-optics-based angle-resolved imaging spectroscopy with an all-fixed light path is developed to measure the dispersions by a single shot,acquiring adequate information.Our forward-mapping algorithm can enable real-time comparisons between robust predictions and experimental data with actual noises,showing an excellent linear correlation(R2>0.982)with the measurements of atomic force microscopy.Our work provides a new strategy for reconstructing grating profiles in inverse scattering problems.展开更多
With the ever-increasing laser power and repetition rate,thermal control of laser media is becoming increasingly important.Except for widely used air cooling or a bonded heat sink,water cooling of a laser medium is mo...With the ever-increasing laser power and repetition rate,thermal control of laser media is becoming increasingly important.Except for widely used air cooling or a bonded heat sink,water cooling of a laser medium is more effective in removing waste heat.However,how to protect deliquescent laser media from water erosion is a challenging issue.Here,novel waterproof coatings were proposed to shield Nd:Glass from water erosion.After clarifying the dependence of the waterproof property of single layers on their microstructures and pore characteristics,nanocomposites that dope SiO_(2) in HfO_(2) were synthesized using an ion-assisted co-evaporation process to solve the issue of a lack of a highindex material that simultaneously has a dense amorphous microstructure and wide bandgap.Hf_(0.7)Si_(0.3)O_(2)/SiO_(2) multifunctional coatings were finally shown to possess an excellent waterproof property,high laser-induced damage threshold(LIDT)and good spectral performance,which can be used as the enabling components for thermal control in high-power laser cavities.展开更多
Exciton physics in atomically thin transition-metal dichalcogenides(TMDCs)holds paramount importance for fundamental physics research and prospective applications.However,the experimental exploration of exciton physic...Exciton physics in atomically thin transition-metal dichalcogenides(TMDCs)holds paramount importance for fundamental physics research and prospective applications.However,the experimental exploration of exciton physics,including excitonic coherence dynamics,exciton many-body interactions,and their optical properties,faces challenges stemming from factors such as spatial heterogeneity and intricate many-body effects.In this perspective,we elaborate upon how optical two-dimensional coherent spectroscopy(2DCS)emerges as an effective tool to tackle the challenges,and outline potential directions for gaining deeper insights into exciton physics in forthcoming experiments with the advancements in 2DCS techniques and new materials.展开更多
Thin-film beam combining technology is an effective approach to improve output power while maintaining beam quality However,the lack of comprehensive research into the key factors affecting the beam quality in systems...Thin-film beam combining technology is an effective approach to improve output power while maintaining beam quality However,the lack of comprehensive research into the key factors affecting the beam quality in systems makes it challenging to achieve a practical combined beam source with high brightness.This paper clearly established that the temperature rise of dichroic mirrors (DMs) and sub-beam overlapping precision are the main factors affecting the beam quality of the system,with quantified effects.Based on this understanding,a combined light source of four channels of3 kW fiber lasers was achieved,and an output power of 11.4 kW with a beam quality of M_(x)^(2)=1.601 and M_(y)^(2)=1.558using three high-steepness low-absorption DMs and the active control technique.To the best of our knowledge,this is the best beam quality for a 10 kW light source.This study offers a solution for practical high-power laser sources in the tens of kilowatts range.展开更多
基金supported by the National Natural Science Foundation of China(Grant Nos.62192774,62105243,61925504,6201101335,62020106009,62192770,62192772,62105244,62305250,and 62322217)the Science and Technology Commission of Shanghai Municipality(Grant Nos.17JC1400800,20JC1414600,and 21JC1406100)+1 种基金the Shanghai Municipal Science and Technology Major Project(Grant No.2021SHZDZX0100)the Fundamental Research Funds for the Central Universities.
文摘Manufacturing-robust imaging systems leveraging computational optics hold immense potential for easing manufacturing constraints and enabling the development of cost-effective,high-quality imaging solutions.However,conventional approaches,which typically rely on data-driven neural networks to correct optical aberrations caused by manufacturing errors,are constrained by the lack of effective tolerance analysis methods for quantitatively evaluating manufacturing error boundaries.This limitation is crucial for further relaxing manufacturing constraints and providing practical guidance for fabrication.We propose a physics-informed design paradigm for manufacturing-robust imaging systems with computational optics,integrating a physics-informed tolerance analysis methodology for evaluating manufacturing error boundaries and a physics-informed neural network for image reconstruction.With this approach,we achieve a manufacturing-robust imaging system based on an off-axis three-mirror freeform all-aluminum design,delivering a modulation transfer function exceeding 0.34 at the Nyquist frequency(72 lp/mm)in simulation.Notably,this system requires a manufacturing precision of only 0.5λin root mean square(RMS),representing a remarkable 25-fold relaxation compared with the conventional requirement of 0.02λin RMS.Experimental validation further confirmed that the manufacturing-robust imaging system maintains excellent performance in diverse indoor and outdoor environments.Our proposed method paves the way for achieving high-quality imaging without the necessity of high manufacturing precision,enabling practical solutions that are more cost-effective and time-efficient.
基金Project supported by the National Natural Science Foundation of China (Grant Nos. 61925504 and 52475563)the National Key Research and Development Program of China (Grant Nos. 2022YFF0607600 and 2022YFF0605502)+1 种基金Key Laboratory of Metrology and Calibration Technology Fund Project (Grant No. JLKG2023001B001)Aeronautical Science Foundation Project (Grant No. 20230056038001)。
文摘Traceability is the fundamental premise of all metrological activities. The establishment of a traceability chain characterized by a shortened structure, while simultaneously enabling on-site traceability, represents a key trend in the advancement of metrology. This study explores the periodic accuracy and overall uniformity of self-traceable gratings, employing multilayer film gratings with a nominal period of 25.00 nm as the medium. We present a comparative analysis of measurement capabilities in a self-traceable grating calibration system characterized by a ‘top-down’ calibration approach and a Si lattice constant calibration system characterized by a ‘bottom-up’ calibration approach. The results indicate that the values obtained for the multilayer film grating periods, calibrated using the self-traceable grating system, are 24.40 nm with a standard deviation of 0.11 nm. By comparing with the values derived from the Si lattice constant, which yield 24.34 nm with a standard deviation of 0.14 nm, the validity and feasibility of the self-traceable calibration system are confirmed. This system extends and complements existing metrological frameworks, offering a precise pathway for traceability in precision engineering and nanotechnology research.
基金supported by the National Key Scientific Instrument and Equipment Development Projects of China(Grant No.2014YQ090709)the National Key Research and Development Program of China(Grant No.2016YFA0200902)Major Projects of Science and Technology Commission of Shanghai,China(Grant No.17JC1400800)
文摘Developing highly accurate critical dimension standards is a significant task for nanoscale metrology. In this paper, we put forward an alternative approach to fabricate amorphous Si critical dimension structures with direct Si lattice calibration in the same frame scanning transmission electron microscopy image. Based on the traceable measurement analysis, the optimized method can provide the same calibration accuracy and increase the fabrication throughput and lower the cost simultaneously, which benefits the application needs in atomic force microscopy(AFM) tip geometry characterization,benchmarking measurement tools, and conducting comparison measurements between different approaches.
基金supported by the National Key Research and Development Program of China(Grant No.2020YFF0218403)the Basic Scientific Research Operating Fund of NIM(Grant No.AKYZD2007-1)。
文摘The line width(often synonymously used for critical dimension,CD)is a crucial parameter in integrated circuits.To accurately control CD values in manufacturing,a reasonable CD reference material is required to calibrate the corresponding instruments.We develop a new reference material with nominal CDs of 160 nm,80 nm,and 40 nm.The line features are investigated based on the metrological scanning electron microscope which is developed by the National Institute of Metrology(NIM)in China.Also,we propose a new characterization method for the precise measurement of CD values.After filtering and leveling the intensity profiles,the line features are characterized by the combination model of the Gaussian and Lorentz functions.The left and right edges of CD are automatically extracted with the profile decomposition and k-means algorithm.Then the width of the two edges at the half intensity position is regarded as the standard CD value.Finally,the measurement results are evaluated in terms of the sample,instrument,algorithm,and repeatability.The experiments indicate efficiency of the proposed method which can be easily applied in practice to accurately characterize CDs.
基金supported by the National Natural Science Foundation of China(61975026,62375232,6237523262205246 and 61875030)Creative Research Groups of the National Natural Science Foundation of Sichuan Province(2023NSFSC1973)+1 种基金the Shanghai Pilot Program for Basic Research,the National Key Research and Development Program of China(No.2023YFF0613600)Science and Technology Commission of Shanghai Municipality(No.22ZR1432400).
文摘Design of multiple-feed lens antennas requires multivariate and multi-objective optimization processes,which can be accelerated by PSO algorithms.However,the PSO algorithm often fails to achieve optimal results with limited computation resources since spaces of candidate solutions are quite large for lens antenna designs.This paper presents a design paradigm for multiple-feed lens antennas based on a physics-assisted particle swarm optimization(PA-PSO)algorithm,which guides the swarm of particles based on laws of physics.As a proof of concept,a design of compact metalens antenna is proposed,which measures unprecedented performances,such as a field of view at±55°,a 21.7 dBi gain with a flatness within 4 dB,a 3-dB bandwidth>12°,and a compact design with a f-number of 0.2.The proposed PA-PSO algorithm reaches the optimal results 6 times faster than the ordinary PSO algorithm,which endows promising applications in the multivariate and multi-objective optimization processes,including but not limited to metalens antenna designs.
基金Project supported by the National Key Research and Development Program of China(Grant No.2016YFA0200902)Science and Technology Commission of Shanghai Municipality,China(Grant No.17JC1400801)Young Scientists Fund of the National Natural Science Foundation of China(Grant No.51705369).
文摘Laser focused atomic deposition is a unique and effective way to fabricate highly accurate pitch standards in nanometrology.However,the stability and repeatability of the atom lithography fabrication process remains a challenging problem for massive production.Based on the atom-light interaction theory,channeling is utilized to improve the stability and repeatability.From the comparison of three kinds of atom-light interaction models,the optimal parameters for channeling are obtained based on simulation.According to the experimental observations,the peak to valley height of Cr nano-gratings keeps stable when the cutting proportion changes from 15%to 50%,which means that the channeling shows up under this condition.The channeling proves to be an effective method to optimize the stability and repeatability of laser focused Cr atomic deposition.
基金Supported by the RFBR under Grant No 17-57-53091the National Natural Science Foundation of China under Grant No11611530687
文摘An approach for studying the influence of nano-particles on the structural properties of deposited thin films is proposed. It is based on the molecular dynamic modeling of the deposition process in the presence of contaminating nano-particles. The nano-particle is assumed to be immobile and its interaction with film atoms is described by a spherically symmetric potential. The approach is applied to the investigation of properties of silicon dioxide films. Visualization tools are used to investigate the porosity associated with nano-particles. The structure of the film near the nano-particle is studied using the radial distribution function. It is found that fluctuations of film density near the nano-particles are essentially different in the cases of low-energy and high-energy deposition processes.
基金supported by National Key Research and Development Program of China(2023YFF0613600)National Natural Science Foundation of China(61925504,62205246,61621001,62192770,62192772,12274296,62020106009 and 62111530053)+4 种基金Shanghai Pujiang Program(23PJ1413700)Shanghai Pilot Program for Basic Research,Science and Technology Commission of Shanghai Municipality(17JC1400800,20JC1414600,21JC1406100 and 22ZR1432400)the“Shu Guang”project supported by Shanghai Municipal Education Commission and Shanghai Education(17SG22)Fundamental Research Funds for the Central Universities.Q.S.acknowledges the funding support from the National Natural Science Foundation of China(No.12204264)the Shenzhen Stability Support Program(No.WDZC20220810152404001).
文摘Optical sorting combines optical tweezers with diverse techniques,including optical spectrum,artificial intelligence(AI)and immunoassay,to endow unprecedented capabilities in particle sorting.In comparison to other methods such as microfluidics,acoustics and electrophoresis,optical sorting offers appreciable advantages in nanoscale precision,high resolution,non-invasiveness,and is becoming increasingly indispensable in fields of biophysics,chemistry,and materials science.This review aims to offer a comprehensive overview of the history,development,and perspectives of various optical sorting techniques,categorised as passive and active sorting methods.To begin,we elucidate the fundamental physics and attributes of both conventional and exotic optical forces.We then explore sorting capabilities of active optical sorting,which fuses optical tweezers with a diversity of techniques,including Raman spectroscopy and machine learning.Afterwards,we reveal the essential roles played by deterministic light fields,configured with lens systems or metasurfaces,in the passive sorting of particles based on their varying sizes and shapes,sorting resolutions and speeds.We conclude with our vision of the most promising and futuristic directions,including AI-facilitated ultrafast and bio-morphology-selective sorting.It can be envisioned that optical sorting will inevitably become a revolutionary tool in scientific research and practical biomedical applications.
基金support from the National Natural Science Foundation of China(Grant No.62275078,12204165,52221001,62205250,12421005,62475069)Natural Science Foundation of Hunan Province(Grant No.2022JJ20020,2023JJ40112)+2 种基金the Science and Technology Innovation Program of Hunan Province(Grant No.2023RC3101)the Hunan Major Sci-Tech Program(Grant No.2023ZJ1010)Shenzhen Science and Technology Program(GrantNo.JCYJ20220530160405013).
文摘Accurately and swiftly characterizing the state of polarization(SoP)of complex structured light is crucial in the realms of classical and quantum optics.Conventional strategies for detecting SoP,which typically involves a sequence of cascaded optical elements,are bulky,complex,and run counter to miniaturization and integration.While metasurfaceenabled polarimetry has emerged to overcome these limitations,its functionality predominantly remains confined to identifying SoP within the standard Poincare sphere framework.The comprehensive detection of SoP on the higherorder Poincare sphere(HOPS),however,continues to be a huge challenge.Here,we propose a general polarization metrology method capable of fully detecting SoP on any HOPS through a single measurement.The underlying mechanism relies on transforming the optical singularities and Stokes parameters into visualized intensity patterns,facilitating the extraction of all parameters that fully determine a SoP.We actualize this concept through a novel metadevice known as the metasurface photonics polarization clock,which offers an intuitive display of SoP using four distinct pointers.As a proof of concept,we theoretically and experimentally demonstrate fully resolving SoPs on the Oth,1st,and 2nd HOPSs.Our implementation opens up a new pathway towards real-time polarimetry of arbitrary beams featuring miniaturized size,a simple detection process,and a direct readout mechanism,promising significant advancements in fields reliant on polarization.
基金National Key Research and Development Program of China(2023YFF0615604)National Natural Science Foundation of China(62192770,62305252,62205246,62475192,61925504,62020106009,62192771)+3 种基金Science and Technology Commission of Shanghai Municipality(21JC1406100,22ZR1432400)Shanghai Municipal Science and Technology Major Project(2021SHZDZX0100)Shanghai Pilot Program for Basic ResearchFundamental Research Funds for the Central Universities。
文摘Circular dichroism(CD)spectroscopy,widely used for chiral sensing,has been limited by the detection sensitivity.Enhancing optical chirality in the light fields interacting with chiral molecules is crucial for achieving ultrasensitive chiral detection.Here,we present a new paradigm for ultrasensitive chiral detection by creating accessible chiral hotspots using a toroidal dipole Fabry–Perot bound state in the continuum(TD FP-BIC)metasurface.BIC resonance is achieved by controlling the coupling between the TD resonance and its multilayer reflector-induced perfect mirror image.This method enables unprecedented local maximum and average optical chirality enhancements of up to 6×10^(4)-fold and 2×10^(3)-fold,respectively,within non-structured regions,resulting in an 866-fold increase in CD signals compared to chiral molecules alone without nanostructures.Our results pave the way for enhanced light–matter interactions and ultrasensitive enantiomeric operation.
基金support by the National Natural Science Foundarion of China(Grant No.52005175,5211101255)Natural gcience Foundation of Hunan Province of China(Grant No.2020J15059)+1 种基金Shenzhen Science and Technology Program(Grant No.RCBS20200714114855118)the Tribology Science Fund of State Key Laboratory of Tribology(SKILTKF20B04)。
文摘Replacing electrons with photons is a compelling route toward high-speed,massively parallel,and low-power artificial intelligence computing.Recently,diffractive networks composed of phase surfaces were trained to perform machine learning tasks through linear optical transformations.However,the existing architectures often comprise bulky components and,most critically,they cannot mimic the human brain for multitasking.Here,we demonstrate a multi-skilled diffractive neural network based on a metasurface device,which can perform on-chip multi-channel sensing and multitasking in the visible.The polarization multiplexing scheme of the subwavelength nanostructures is applied to construct a multi-channel classifier framework for simultaneous recognition of digital and fashionable items.The areal density of the artificial neurons can reach up to 6.25×10^(6)mm^(-2) multiplied by the number of channels.The metasurface is integrated with the mature complementary metal-oxide semiconductor imaging sensor,providing a chip-scale architecture to process information directly at physical layers for energy-efficient and ultra-fast image processing in machine vision,autonomous driving,and precision medicine.
基金This work was partly supported by the National Natural Science Foundation of China(Grant Nos.61235011,61008030,61108014,61205124)the ChenGuang Project of Shanghai Municipal Education Commission(Grant No.10CG19)+1 种基金the Specialized Research Fund for the Doctoral Program of High Education(Grant No.20100072120037)the National 863 Program.
文摘Thermomechanical damage of nodules in dielectric multilayer coatings that are irradiated by nanosecond laser pulses has been interpreted with respect to mechanical properties and electric-field enhancement.However,the effect of electric-field enhancement in nodular damage,especially the influence of electric-field distributions,has never been directly demonstrated through experimental results,which prevents the achievement of a clear understanding of the damage process of nodular defects.Here,a systematic and comparative study was designed to reveal how electric-field distributions affect the damage behavior of nodules.To obtain reliable results,two series of artificial nodules with different geometries and film absorption characteristics were prepared from monodisperse silica microspheres.After establishing simplified geometrical models of the nodules,the electric-field enhancement was simulated using a three-dimensional finite-difference time-domain code.Then,the damage morphologies of the artificial nodules were directly compared with the simulated electric-field intensity profiles.For both series of nodules,the damage morphologies reproduced our simulated electric-field intensity distributions very well.These results indicated that the electric-field distribution was actually a bridge that connected the nodular mechanical properties to the final thermomechanical damage.Understanding of the damage mechanism of nodules was deepened by obtaining data on the influence of electric-field distributions on the damage behavior of nodules.
基金supported by the National Natural Science Foundation of China (61925504, 62192770, 62305252, 61621001, 62205246, 62020106009, 6201101335, 62205249, 62192772, 62192771)Shanghai Pilot Program for Basic Research, Science and Technology Commission of Shanghai Municipality (17JC1400800, 20JC1414600, 21JC1406100)+3 种基金the “Shu Guang” project supported by Shanghai Municipal Education Commission and Shanghai Education (17SG22)Shanghai Municipal Science and Technology Major Project (2021SHZDZX0100)Special Development Funds for Major Projects of Shanghai Zhangjiang National Independent Innovation Demonstration Zone (Grant No. ZJ2021-ZD-008)The Fundamental Research Funds for the Central Universities, Project funded by China Postdoctoral Science Foundation (2022M712401).
文摘Exceptional point (EP) is a special degeneracy of non-Hermitian systems. One-dimensional transmission systems operating at EPs are widely studied and applied to chiral conversion and sensing. Lately, two-dimensional systems at EPs have been exploited for their exotic scattering features, yet so far been limited to only the non-visible waveband. Here, we report a universal paradigm for achieving a high-efficiency EP in the visible by leveraging interlayer loss to accurately control the interplay between the lossy structure and scattering lightwaves. A bilayer framework is demonstrated to reflect back the incident light from the left side ( | r_(−1) | >0.999) and absorb the incident light from the right side ( | r_(+1) | < 10^(–4)). As a proof of concept, a bilayer metasurface is demonstrated to reflect and absorb the incident light with experimental efficiencies of 88% and 85%, respectively, at 532 nm. Our results open the way for a new class of nanoscale devices and power up new opportunities for EP physics.
基金National Natural Science Foundation of China(61522506,61621001,U1630124,U1630123)National Program on Key Research Project(2016YFA0200900)Innovation Program of Shanghai Municipal Education Commission。
文摘Double-layer high-contrast subwavelength gratings that are separated by a dielectric space layer are investigated to achieve ultra-broadband reflection.The reflection phase of subwavelength gratings and the propagation phase shift between two gratings are manipulated to expand reflection bandwidth by properly stacking two reflective gratings.A reflector exhibiting a 99%reflectance bandwidth of^1080 nm in the near-infrared is designed.Then this reflector is prepared using laser interference lithography and ion beam planarization,and an ultra-broadband reflection is achieved with reflectance exceeding 97%over a wavelength range of 955 nm in the near-infrared region.
基金supported by Significant Development Project of Shanghai Zhangjiang National Innovation Benchmarking Zone(Grant No.ZJ2021-ZD-008)National Natural Science Foundation of China(Grant No.62075165)+3 种基金Science and Technology Commission of Shanghai(Grant No.208014043)Shanghai Municipal Science and Technology Major Project(2021SHZDZX0100)the Fundamental Research Funds for the Central UniversitiesOpening Fund from Shanghai Key Laboratory of Online Detection and Control Technology of SIMT.
文摘Atom lithography is a unique method to fabricate self-traceable pitch standards and angle standards,but extending its structure area to millimeter-level for application is challenging.In this paper,on the one hand,we put forward a new approach to fabricate a full-covered self-traceable Cr nanograting by inserting and scanning a Dove prism in the Gaussian beam direction of atom lithography.On the other hand,we extend the structure area along the standing-wave direction by splicing two-step atom deposition.Both nanostructures manufactured via scanning atom lithography and splicing atom lithography demonstrate good pitch accuracy,parallelism,continuity,and homogeneity,which opens a new way to fabricate centimeter-level full-covered self-traceable nanograting and lays the basis for the application of square ruler and optical encoders at the nanoscale.
基金supported by the National Natural Science Foundation of China(Nos.61675156 and 61975153)。
文摘The influence of nodule defects on the characteristics of femtosecond laser-induced damage has not been fully investigated.In this study,two types of 800 nm/1064 nm dual-band HfO_(2)=Si O_(2) high-reflection films with different configurations were analyzed.Combined with finite-difference time-domain electric field simulation and focused ion beam analysis,the initial state and growth process of femtosecond laser damage of nodules were explored.In particular,the sequence of blister damage determined by the film design and the inner damage caused by nodules were clarified.The rule of the laser-induced damage threshold of different size nodules was obtained.The difference in the damage behavior of nodules in the two types of films was elucidated.
基金The work was supported by the China National Key Basic Research Program(2016YFA0301103,2016YFA0302000 and 2018YFA0306201)the National Science Foundation of China(11774063,11727811,91750102 and 91963212)+1 种基金A.C.was supported by Shanghai Rising-Star Program(20QB1402200)L.S.was further supported by the Science and Technology Commission of Shanghai Municipality(19XD1434600,2019SHZDZX01,and 19DZ2253000).
文摘Inferring the properties of a scattering objective by analyzing the optical far-field responses within the framework of inverse problems is of great practical significance.However,it still faces major challenges when the parameter range is growing and involves inevitable experimental noises.Here,we propose a solving strategy containing robust neuralnetworks-based algorithms and informative photonic dispersions to overcome such challenges for a sort of inverse scattering problem—reconstructing grating profiles.Using two typical neural networks,forward-mapping type and inverse-mapping type,we reconstruct grating profiles whose geometric features span hundreds of nanometers with nanometric sensitivity and several seconds of time consumption.A forward-mapping neural network with a parameters-to-point architecture especially stands out in generating analytical photonic dispersions accurately,featured by sharp Fano-shaped spectra.Meanwhile,to implement the strategy experimentally,a Fourier-optics-based angle-resolved imaging spectroscopy with an all-fixed light path is developed to measure the dispersions by a single shot,acquiring adequate information.Our forward-mapping algorithm can enable real-time comparisons between robust predictions and experimental data with actual noises,showing an excellent linear correlation(R2>0.982)with the measurements of atomic force microscopy.Our work provides a new strategy for reconstructing grating profiles in inverse scattering problems.
基金supported by the National Natural Science Foundation of China(Nos.61522506,51475335,61621001 and 91536111)Joint Sino-German Research Project(No.GZ1275)+3 种基金National Program on Key Research Project(No.2016YFA0200900)Major projects of Science and Technology Commission of Shanghai(No.17JC1400800)“Shu Guang”project supported by Shanghai Municipal Education Commission and Shanghai Education(No.17SG22)Development Foundation National Key Scientific Instrument and Equipment Development Project(No.2014YQ090709).
文摘With the ever-increasing laser power and repetition rate,thermal control of laser media is becoming increasingly important.Except for widely used air cooling or a bonded heat sink,water cooling of a laser medium is more effective in removing waste heat.However,how to protect deliquescent laser media from water erosion is a challenging issue.Here,novel waterproof coatings were proposed to shield Nd:Glass from water erosion.After clarifying the dependence of the waterproof property of single layers on their microstructures and pore characteristics,nanocomposites that dope SiO_(2) in HfO_(2) were synthesized using an ion-assisted co-evaporation process to solve the issue of a lack of a highindex material that simultaneously has a dense amorphous microstructure and wide bandgap.Hf_(0.7)Si_(0.3)O_(2)/SiO_(2) multifunctional coatings were finally shown to possess an excellent waterproof property,high laser-induced damage threshold(LIDT)and good spectral performance,which can be used as the enabling components for thermal control in high-power laser cavities.
基金S.Y.and X.L.acknowledge the support from the National Natural Science Foundation of China(Grant Nos.12121004 and 12004391)the China Postdoctoral Science Foundation(Grants Nos.2020T130682 and 2019M662752)+6 种基金the Science and Technology Department of Hubei Province(Grant No.2020CFA029)the Knowledge Innovation Program of Wuhan-Shuguang Project.T.J.acknowledges the support from the National Natural Science Foundation of China(Grant Nos.62175188 and 62005198)the Shanghai Science and Technology Innovation Action Plan Project(Grant No.23ZR1465800)X.C.acknowledges support from the National Natural Science Foundation of China(Grant Nos.61925504,62020106009,and 6201101335)Science and Technology Commission of Shanghai Municipality(Grant Nos.17JC1400800,20JC1414600,and 21JC1406100)the Special Development Funds for Major Projects of Shanghai Zhangjiang National Independent Innovation Demonstration Zone(Grant No.ZJ2021-ZD-008)D.H.acknowledges the support from the Fundamental Research Funds for the Central Universities.
文摘Exciton physics in atomically thin transition-metal dichalcogenides(TMDCs)holds paramount importance for fundamental physics research and prospective applications.However,the experimental exploration of exciton physics,including excitonic coherence dynamics,exciton many-body interactions,and their optical properties,faces challenges stemming from factors such as spatial heterogeneity and intricate many-body effects.In this perspective,we elaborate upon how optical two-dimensional coherent spectroscopy(2DCS)emerges as an effective tool to tackle the challenges,and outline potential directions for gaining deeper insights into exciton physics in forthcoming experiments with the advancements in 2DCS techniques and new materials.
基金supported by the National Natural Science Foundation of China (Nos. 62061136008, 62275196, 62192772, 62305251, 61925504, 61975153, 6201101335, 62020106009, 62192770 and 61621001)Science and Technology Commission of Shanghai Municipality (Nos. 17JC1400800, 20JC1414600 and 21JC1406100)+3 种基金Special Development Funds for Major Projects of Shanghai Zhangjiang National Independent Innovation Demonstration Zone (No. ZJ2021-ZD-008)Shanghai Municipal Science and Technology Major Project (No. 2021SHZDZX0100)Fundamental Research Funds for the Central UniversitiesNational Key R&D Program of China (No. 2022YFA1603403)。
文摘Thin-film beam combining technology is an effective approach to improve output power while maintaining beam quality However,the lack of comprehensive research into the key factors affecting the beam quality in systems makes it challenging to achieve a practical combined beam source with high brightness.This paper clearly established that the temperature rise of dichroic mirrors (DMs) and sub-beam overlapping precision are the main factors affecting the beam quality of the system,with quantified effects.Based on this understanding,a combined light source of four channels of3 kW fiber lasers was achieved,and an output power of 11.4 kW with a beam quality of M_(x)^(2)=1.601 and M_(y)^(2)=1.558using three high-steepness low-absorption DMs and the active control technique.To the best of our knowledge,this is the best beam quality for a 10 kW light source.This study offers a solution for practical high-power laser sources in the tens of kilowatts range.
