As a two-dimensional planar material with low depth profile,a metasurface can generate non-classical phase distributions for the transmitted and reflected electromagnetic waves at its interface.Thus,it offers more fle...As a two-dimensional planar material with low depth profile,a metasurface can generate non-classical phase distributions for the transmitted and reflected electromagnetic waves at its interface.Thus,it offers more flexibility to control the wave front.A traditional metasurface design process mainly adopts the forward prediction algorithm,such as Finite Difference Time Domain,combined with manual parameter optimization.However,such methods are time-consuming,and it is difficult to keep the practical meta-atom spectrum being consistent with the ideal one.In addition,since the periodic boundary condition is used in the meta-atom design process,while the aperiodic condition is used in the array simulation,the coupling between neighboring meta-atoms leads to inevitable inaccuracy.In this review,representative intelligent methods for metasurface design are introduced and discussed,including machine learning,physics-information neural network,and topology optimization method.We elaborate on the principle of each approach,analyze their advantages and limitations,and discuss their potential applications.We also summarize recent advances in enabled metasurfaces for quantum optics applications.In short,this paper highlights a promising direction for intelligent metasurface designs and applications for future quantum optics research and serves as an up-to-date reference for researchers in the metasurface and metamaterial fields.展开更多
Optical tweezers have proved to be a powerful tool with a wide range of applications.The gradient force plays a vital role in the stable optical trapping of nano-objects.The scalar method is convenient and effective f...Optical tweezers have proved to be a powerful tool with a wide range of applications.The gradient force plays a vital role in the stable optical trapping of nano-objects.The scalar method is convenient and effective for analyzing the gradient force in traditional optical trapping.However,when the third-order nonlinear effect of the nano-object is stimulated,the scalar method cannot adequately present the optical response of the metal nanoparticle to the external optical field.Here,we propose a theoretical model to interpret the nonlinear gradient force using the vector method.By combining the optical Kerr effect,the polarizability vector of the metallic nanoparticle is derived.A quantitative analysis is obtained for the gradient force as well as for the optical potential well.The vector method yields better agreement with reported experimental observations.We suggest that this method could lead to a deeper understanding of the physics relevant to nonlinear optical trapping and binding phenomena.展开更多
Ptychographic extreme ultraviolet(EUV)diffractive imaging has emerged as a promising candidate for the next generationmetrology solutions in the semiconductor industry,as it can image wafer samples in reflection geome...Ptychographic extreme ultraviolet(EUV)diffractive imaging has emerged as a promising candidate for the next generationmetrology solutions in the semiconductor industry,as it can image wafer samples in reflection geometry at the nanoscale.This technique has surged attention recently,owing to the significant progress in high-harmonic generation(HHG)EUV sources and advancements in both hardware and software for computation.In this study,a novel algorithm is introduced and tested,which enables wavelength-multiplexed reconstruction that enhances the measurement throughput and introduces data diversity,allowing the accurate characterisation of sample structures.To tackle the inherent instabilities of the HHG source,a modal approach was adopted,which represents the crossdensity function of the illumination by a series of mutually incoherent and independent spatial modes.The proposed algorithm was implemented on a mainstream machine learning platform,which leverages automatic differentiation to manage the drastic growth in model complexity and expedites the computation using GPU acceleration.By optimising over 2oo million parameters,we demonstrate the algorithm's capacity to accommodate experimental uncertainties and achieve a resolution approaching the diffraction limit in reflection geometry.The reconstruction of wafer samples with 20-nm high patterned gold structures on a silicon substrate highlights our ability to handle complex physical interrelations involving a multitude of parameters.These results establish ptychography as an efficient and accurate metrology tool.展开更多
Deformation behavior as well as microstructural evolutions of a rolled AZ31 magnesium alloy with and without pre-existing extension twins were studied using compression tests which performed along different orientatio...Deformation behavior as well as microstructural evolutions of a rolled AZ31 magnesium alloy with and without pre-existing extension twins were studied using compression tests which performed along different orientations at a temperature range of 25–350 ℃. The results implied that the initial texture not only influence the evolution of flow stress, but also change the size and fraction of recrystallized grains.In contrast to samples parallel to rolling and transverse directions, compression along normal direction resulted in a respectful softening at 150 ℃. The largest size and fraction of new grains at 250 ℃ were recorded after deformation along rolling direction, while the maximum flow softening was observed during deformation along normal direction. The anisotropy in microstructural evolutions was still retained at 350 ℃. Pre-existing twins could reduce the anisotropy of material in respect of flow stress as well as DRX progression, where TD sample showed the lowest DRX fraction at 250 ℃. Quaternion misorientation data obtained from EBSD analysis of pretwinned material implied that initial texture could not significantly influence final texture. A different misorientation distribution was realized after deformation of pretwinned material along ND and RD directions.展开更多
Amplitude, phase and polarization are essential parameters of an optical field. In the past decade, with the enhancement of techniques in manipulating phase and polarization states in complex optical fields, optical v...Amplitude, phase and polarization are essential parameters of an optical field. In the past decade, with the enhancement of techniques in manipulating phase and polarization states in complex optical fields, optical vortices and vector beams are investigated in a closely coupled fashion in terms of efficient beam generation and manipulation, stable transmission and novel detection aimed at various applications. In this special issue 6 invited papers demonstrate a number of typical topics in the field, with emphasis on the vectorial beam generation and optical communication systems utilising orbital angular momentum(OAM).展开更多
文摘As a two-dimensional planar material with low depth profile,a metasurface can generate non-classical phase distributions for the transmitted and reflected electromagnetic waves at its interface.Thus,it offers more flexibility to control the wave front.A traditional metasurface design process mainly adopts the forward prediction algorithm,such as Finite Difference Time Domain,combined with manual parameter optimization.However,such methods are time-consuming,and it is difficult to keep the practical meta-atom spectrum being consistent with the ideal one.In addition,since the periodic boundary condition is used in the meta-atom design process,while the aperiodic condition is used in the array simulation,the coupling between neighboring meta-atoms leads to inevitable inaccuracy.In this review,representative intelligent methods for metasurface design are introduced and discussed,including machine learning,physics-information neural network,and topology optimization method.We elaborate on the principle of each approach,analyze their advantages and limitations,and discuss their potential applications.We also summarize recent advances in enabled metasurfaces for quantum optics applications.In short,this paper highlights a promising direction for intelligent metasurface designs and applications for future quantum optics research and serves as an up-to-date reference for researchers in the metasurface and metamaterial fields.
基金supported by the Key Research Project of Zhejiang Lab(No.2022MG0AC05)the Guangdong Major Project of Basic and Applied Basic Research(No.2020B0301030009)+3 种基金the National Natural Science Foundation of China(Nos.61975128,61935013,and 62175157)the Shenzhen Science and Technology Program(Nos.JCYJ20210324120403011 and RCJC20210609103232046)the Natural Science Foundation of Guangdong Province(No.2019TQ05X750)the Shenzhen Peacock Plan(No.KQTD20170330110444030)。
文摘Optical tweezers have proved to be a powerful tool with a wide range of applications.The gradient force plays a vital role in the stable optical trapping of nano-objects.The scalar method is convenient and effective for analyzing the gradient force in traditional optical trapping.However,when the third-order nonlinear effect of the nano-object is stimulated,the scalar method cannot adequately present the optical response of the metal nanoparticle to the external optical field.Here,we propose a theoretical model to interpret the nonlinear gradient force using the vector method.By combining the optical Kerr effect,the polarizability vector of the metallic nanoparticle is derived.A quantitative analysis is obtained for the gradient force as well as for the optical potential well.The vector method yields better agreement with reported experimental observations.We suggest that this method could lead to a deeper understanding of the physics relevant to nonlinear optical trapping and binding phenomena.
基金the project Lensless Imaging of 3D Nanostructures with Soft X-Rays(LINX)with project number P16-08 of the Perspectief research programme financed by the Dutch Research Council(NWO).
文摘Ptychographic extreme ultraviolet(EUV)diffractive imaging has emerged as a promising candidate for the next generationmetrology solutions in the semiconductor industry,as it can image wafer samples in reflection geometry at the nanoscale.This technique has surged attention recently,owing to the significant progress in high-harmonic generation(HHG)EUV sources and advancements in both hardware and software for computation.In this study,a novel algorithm is introduced and tested,which enables wavelength-multiplexed reconstruction that enhances the measurement throughput and introduces data diversity,allowing the accurate characterisation of sample structures.To tackle the inherent instabilities of the HHG source,a modal approach was adopted,which represents the crossdensity function of the illumination by a series of mutually incoherent and independent spatial modes.The proposed algorithm was implemented on a mainstream machine learning platform,which leverages automatic differentiation to manage the drastic growth in model complexity and expedites the computation using GPU acceleration.By optimising over 2oo million parameters,we demonstrate the algorithm's capacity to accommodate experimental uncertainties and achieve a resolution approaching the diffraction limit in reflection geometry.The reconstruction of wafer samples with 20-nm high patterned gold structures on a silicon substrate highlights our ability to handle complex physical interrelations involving a multitude of parameters.These results establish ptychography as an efficient and accurate metrology tool.
基金supported in part by the National Science Center (Poland) under grant No. 2018/31/B/ST8/00942。
文摘Deformation behavior as well as microstructural evolutions of a rolled AZ31 magnesium alloy with and without pre-existing extension twins were studied using compression tests which performed along different orientations at a temperature range of 25–350 ℃. The results implied that the initial texture not only influence the evolution of flow stress, but also change the size and fraction of recrystallized grains.In contrast to samples parallel to rolling and transverse directions, compression along normal direction resulted in a respectful softening at 150 ℃. The largest size and fraction of new grains at 250 ℃ were recorded after deformation along rolling direction, while the maximum flow softening was observed during deformation along normal direction. The anisotropy in microstructural evolutions was still retained at 350 ℃. Pre-existing twins could reduce the anisotropy of material in respect of flow stress as well as DRX progression, where TD sample showed the lowest DRX fraction at 250 ℃. Quaternion misorientation data obtained from EBSD analysis of pretwinned material implied that initial texture could not significantly influence final texture. A different misorientation distribution was realized after deformation of pretwinned material along ND and RD directions.
文摘Amplitude, phase and polarization are essential parameters of an optical field. In the past decade, with the enhancement of techniques in manipulating phase and polarization states in complex optical fields, optical vortices and vector beams are investigated in a closely coupled fashion in terms of efficient beam generation and manipulation, stable transmission and novel detection aimed at various applications. In this special issue 6 invited papers demonstrate a number of typical topics in the field, with emphasis on the vectorial beam generation and optical communication systems utilising orbital angular momentum(OAM).
