Optical monitoring of object position and alignment with nanoscale precision is critical for ultra-precision measurement applications,such as micro/nano-fabrication,weak force sensing,and micro-scopic imaging.Traditio...Optical monitoring of object position and alignment with nanoscale precision is critical for ultra-precision measurement applications,such as micro/nano-fabrication,weak force sensing,and micro-scopic imaging.Traditional optical nanometry methods often rely on precision nanostructure fabrication,multi-beam interferometry,or complex post-processing algorithms,which can limit their practical use.In this study,we introduced a simplified and robust quantum measurement technique with an achievable resolution of 2.2 pm and an experimental demonstration of 1 nm resolution,distinguishing it from conventional interferometry,which depended on multiple reference beams.We designed a metasurface substrate with a mode-conversion function,in which an incident Gaussian beam is converted into higher-order transverse electromagnetic mode(TEM)modes.A theoretical analysis,including calculations of the Fisher information,demonstrated that the accuracy was maintained for nanoscale displacements.In conclusion,the study findings provide a new approach for precise alignment and metrology of nanofabrication and other advanced applications.展开更多
The optical manipulation of nanoparticles on superlubricity surfaces was investigated.The research revealed that,due to the near-zero static friction and extremely low dynamic friction at superlubricity interfaces,the...The optical manipulation of nanoparticles on superlubricity surfaces was investigated.The research revealed that,due to the near-zero static friction and extremely low dynamic friction at superlubricity interfaces,the maximum intensity for controlling the optical field can be less than 100 W/cm^(2).The controlled nanoparticle radius can be as small as 5 nm,which is more than one order of magnitude smaller than that of nanoparticles controlled through traditional optical manipulation.Manipulation can be achieved on sub-microsecond to microsecond timescales.Furthermore,the manipulation takes place on solid surfaces and in nonliquid environments,with minimal impact from Brownian motion.By appropriately increasing the dynamic friction,controlling the light intensity,or reducing the pressure,the effects of Brownian motion can be eliminated,allowing for the construction of microstructures with a size as small as 1/75 of the wavelength of light while controlling the light intensity,which is seven orders of magnitude smaller compared to manipulating nanoparticles on traditional surfaces.This enables the control of super-resolution optical microstructures.The optical super-resolution manipulation of nanoparticles on superlubricity surfaces has important applications in fields such as nanofabrication,photolithography,optical metasurfaces,and biochemical analysis.展开更多
Lithography is a Key enabling technique in modern micro/nano scale technology.Achieving the optimal trade-off between resolution,throughput,and cost remains a central focus in the ongoing development.However,current l...Lithography is a Key enabling technique in modern micro/nano scale technology.Achieving the optimal trade-off between resolution,throughput,and cost remains a central focus in the ongoing development.However,current lithographic techniques such as direct-write,projection,and extreme ultraviolet lithography achieve higher resolution at the expense of increased complexity in optical systems or the use of shorter-wavelength light sources,thus raising the overall cost of production.Here,we present a cost-effective and wafer-level perfect conformal contact lithography at the diffraction limit.By leveraging a transferable photoresist,the technique ensures optimal contact between the mask and photoresist with zero-gap,facilitating the transfer of patterns at the diffraction limit while maintaining high fidelity and uniformity across large wafers.This technique applies to a wide range of complex surfaces,including non-conductive glass surfaces,flexible substrates,and curved surfaces.The proposed technique expands the potential of contact photolithography for novel device architectures and practic al manufacturing processes.展开更多
Diffraction limited electron storage ring is considered a promising candidate for future light sources,whose main characteristics are higher brilliance,better transverse coherence and better stability.The challenge of...Diffraction limited electron storage ring is considered a promising candidate for future light sources,whose main characteristics are higher brilliance,better transverse coherence and better stability.The challenge of diffraction limited storage ring design is how to achieve the ultra low beam emittance with acceptable nonlinear performance.Effective linear and nonlinear parameter optimization methods based on Artificial Intelligence were developed for the storage ring physical design.As an example of application,partial physical design of HALS(Hefei Advanced Light Source),which is a diffraction limited VUV and soft X-ray light source,was introduced.Severe emittance growth due to the Intra Beam Scattering effect,which is the main obstacle to achieve ultra low emittance,was estimated quantitatively and possible cures were discussed.It is inspiring that better performance of diffraction limited storage ring can be achieved in principle with careful parameter optimization.展开更多
A 1178 J near diffraction limited 527 nm laser is realized in a complete closed-loop adaptive optics(AO)controlled off-axis multi-pass amplification laser system.Generated from a fiber laser and amplified by the pre-a...A 1178 J near diffraction limited 527 nm laser is realized in a complete closed-loop adaptive optics(AO)controlled off-axis multi-pass amplification laser system.Generated from a fiber laser and amplified by the pre-amplifier and the main amplifier,a 1053 nm laser beam with the energy of 1900 J is obtained and converted into a 527 nm laser beam by a KDP crystal with 62%conversion efficiency,1178 J and beam quality of 7.93 times the diffraction limit(DL).By using a complete closed-loop AO configuration,the static and dynamic wavefront distortions of the laser system are measured and compensated.After correction,the diameter of the circle enclosing 80%energy is improved remarkably from 7.93DL to 1.29DL.The focal spot is highly concentrated and the 1178 J,527 nm near diffraction limited laser is achieved.展开更多
In this paper, we extensively study the higher-order harmonic generation of the general limited diffraction m-th- order Bessel beam. The analysis is based on successive approximations of the Khokhlov-Zabolotskaya-Kuzn...In this paper, we extensively study the higher-order harmonic generation of the general limited diffraction m-th- order Bessel beam. The analysis is based on successive approximations of the Khokhlov-Zabolotskaya-Kuznetsov （KZK） equation. Asymptotic expansions are presented for higher-order harmonic Bessel beams in near and far fields. The validity of asymptotic approximation is also analyzed. The higher-order harmonic of the Bessel beam with the lowest zero-order is taken as a special example.展开更多
Objective To investigate a new class of solutions to the isotropic/homogeneous scalar wave equation, which termed limited diffraction beams and realize ultrasonic 3D imaging. Methods Limited diffraction beams were d...Objective To investigate a new class of solutions to the isotropic/homogeneous scalar wave equation, which termed limited diffraction beams and realize ultrasonic 3D imaging. Methods Limited diffraction beams were derived. We performed the study of 3D pulse echo imaging with limited diffraction array beam. To obtain high frame rate images, a single plane wave pulse (broadband) was transmitted with the arrays. Echoes received with the same arrays were processed with Fourier method to construct 3D images. Results Compared with traditional pulse echo imaging, this method has a larger depth of field, high frame rate, and high signal to noise ratio. Conclusion The new method has prospect of high frame rate 3D imaging. In addition, the imaging system based this method is easily implemented and has high quality image.展开更多
In the implementation of CARS nanoscopy, signal strength decreases with focal volume size decreasing. A crucial problem that remains to be solved is whether the reduced signal generated in the suppressed focal volume ...In the implementation of CARS nanoscopy, signal strength decreases with focal volume size decreasing. A crucial problem that remains to be solved is whether the reduced signal generated in the suppressed focal volume can be detected. Here reported is a theoretical analysis of detection limit （DL） to time-resolved CARS （T-CARS） nanoscopy based on our proposed additional probe-beam-induced phonon depletion （APIPD） method for the low concentration samples. In order to acquire a detailed shot-noise limited signal-to-noise （SNR） and the involved parameters to evaluate DL, the T-CARS process is described with full quantum theory to estimate the extreme power density levels of the pump and Stokes beams determined by saturation behavior of coherent phonons, which are both actually on the order of ~ 109 W/cm2. When the pump and Stokes intensities reach such values and the total intensity of the excitation beams arrives at a maximum tolerable by most biological samples in a certain suppressed focal volume （40-nm suppressed focal scale in APIPD method）, the DL correspondingly varies with exposure time, for example, DL values are 103 and 102 when exposure times are 20 ms and 200 ms respectively.展开更多
Supercritical lens(SCL)can break the diffraction limit in the far field and has been demonstrated for high-resolution scanning confocal imaging.Its capability in sharper focusing and needle-like long focal depth shoul...Supercritical lens(SCL)can break the diffraction limit in the far field and has been demonstrated for high-resolution scanning confocal imaging.Its capability in sharper focusing and needle-like long focal depth should allow high-resolution lithography at violet or ultraviolet(UV)wavelength,however,this has never been experimentally demonstrated.As a proof of concept,in this paper SCLs operating at 405 nm(h-line)wavelength with smaller full-width-at-half-maximum focal spot and longer depth of focus than conventional Fresnel zone lens while maintaining controlled side lobes are designed for direct laser writing(DLW)lithography.Aluminum nitride(AlN)with a high refractive index and low loss in UVvisible range is used to fabricate nanopillar-based metasurfaces structure for the metalens.Grating arrays with improved pitch resolution are fabricated using the SCLs with sub-diffraction-limit focusing capability.The AlN-based metasurface for SCLs at short wavelength for DLW could extend further to UV or deep UV lithography and might be of great interest to both the research and industry applications.展开更多
We report a comprehensive numerical study of super resolution (SR) structured illumination microscopy (SIM) utilizing the classic Heintzmann-Cremer SIM process and algorithm. In particular, we investigated the impact ...We report a comprehensive numerical study of super resolution (SR) structured illumination microscopy (SIM) utilizing the classic Heintzmann-Cremer SIM process and algorithm. In particular, we investigated the impact of the diffraction limit of the underlying imaging system on the optimal SIM grating frequency that can be used to obtain the highest SR enhancement with non-continuous spatial frequency support. Besides confirming the previous theoretical and experimental work that SR-SIM can achieve an enhancement close to 3 times the diffraction limit with grating pattern illuminations, we also observe and report a series of more subtle effects of SR-SIM with non-continuous spatial frequency support. Our simulations show that when the SIM grating frequency exceeds twice that of the diffraction limit, the higher SIM grating frequency can help achieve a higher SR enhancement for the underlying imaging systems whose diffraction limit is low, though this enhancement is obtained at the cost of losing resolution at some lower resolution targets. Our simulations also show that, for underlying imaging systems with high diffraction limits, however, SR-SIM grating frequencies above twice the diffraction limits tend to bring no significant extra enhancement. Furthermore, we observed that there exists a limit grating frequency above which the SR enhancement effect is lost, and the reconstructed images essentially have the same resolution as the one obtained directly from the underlying imaging system without using the SIM process.展开更多
Fluorescence microscopy has become an essential tool for biological research because it can be minimally invasive, acquire data rapidly, and target molecules of interest with specific labeling strategies. However, the...Fluorescence microscopy has become an essential tool for biological research because it can be minimally invasive, acquire data rapidly, and target molecules of interest with specific labeling strategies. However, the diffraction-limited spatial resolution, which is classically limited to about 200 nm in the lateral direction and about 500 nm in the axial direction, hampers its application to identify delicate details of subcellular structure. Extensive efforts have been made to break diffraction limit for obtaining high-resolution imaging of a biological specimen. Various methods capable of obtaining super-resolution images with a resolution of tens of nanometers are currently available. These super-resolution techniques can be generally divided into three primary classes： （1） patterned illumination- based super-resolution imaging, which employs spatially and temporally modulated illumination light to reconstruct sub-diffraction structures; （2） single-molecule localization-based super-resolution imaging, which localizes the profile center of each individual fluo- rophore at subdiffraction precision; （3） bleaching/blinking-based super-resolution imaging. These super-resolution techniques have been utilized in different biological fields and provide novel insights into several new aspects of life science. Given unique technical merits and commercial availability of super-resolution fluorescence microscope, increasing applications of this powerful technique in life science can be expected.展开更多
The imaging capability of conventional lenses is mainly limited by the diffraction of light,and the so-called superlens has been developed allowing the recovery of evanescent waves in the focal plane.However,the remar...The imaging capability of conventional lenses is mainly limited by the diffraction of light,and the so-called superlens has been developed allowing the recovery of evanescent waves in the focal plane.However,the remarkable focusing behavi-or of the superlens is greatly confined in the near-field regime due to the exponential decay of evanescent waves.To tackle this issue,we design a waveguide metasurface-based superlens with an extraordinary quasi-far-field focusing capability beyond the diffraction limit in the present work.Specifically,we analyze the underlying physical mechanism and provide experimental verification of the proposed superlens.The metasurface superlens is formed by an array of gradient nanoslits perforated in a gold slab,and supports transverse-electric(TE)waveguide modes under linearly polar-ized illumination along the long axis of the slits.Numerical results illustrate that exciting such TE waveguide modes can modulate not only optical phase but also evanescent waves.Consequently,some high-spatial-frequency waves can con-tribute to the focusing of the superlens,leading to the quasi-far-field super-resolution focusing of light.Under 405 nm illu-mination and oil immersion,the fabricated superlens shows a focus spot of 98 nm(i.e.λ/4.13)at a focal distance of 1.49μm(i.e.3.68λ)using an oil immersion objective,breaking the diffraction limit ofλ/2.38 in the quasi-far field regime.The developed metasurface optical superlens with such extraordinary capabilities promises exciting avenues to nanolitho-graphy and ultra-small optoelectronic devices.展开更多
Optical microscopy allows us to observe the biological structures and processes within living cells.However,the spatial resolution of the optical microscopy is limited to about half of the wavelength by the light di&#...Optical microscopy allows us to observe the biological structures and processes within living cells.However,the spatial resolution of the optical microscopy is limited to about half of the wavelength by the light di®raction.Structured illumination microscopy(SIM),a type of new emerging super-resolution microscopy,doubles the spatial resolution by illuminating the specimen with a patterned light,and the sample and light source requirements of SIM are not as strict as the other super-resolution microscopy.In addition,SIM is easier to combine with the other imaging techniques to improve their imaging resolution,leading to the developments of diverse types of SIM.SIM has great potential to meet the various requirements of living cells imaging.Here,we review the recent developments of SIM and its combination with other imaging techniques.展开更多
Fluorescence nanoscopy provides imaging techniques that overcome the diffraction-limited resolution barrier in light microscopy,thereby opening up a new area of research in biomedical imaging in fields such as neurosc...Fluorescence nanoscopy provides imaging techniques that overcome the diffraction-limited resolution barrier in light microscopy,thereby opening up a new area of research in biomedical imaging in fields such as neuroscience.Here,we review the foremost fluorescence nanoscopy techniques,including descriptions of their applications in elucidating protein architectures and mobility,the real-time determination of synaptic parameters involved in neural processes,three-dimensional imaging,and the tracking of nanoscale neural activity.We conclude by discussing the prospects of fluorescence nanoscopy,with a particular focus on its deployment in combination with related techniques(e.g.,machine learning)in neuroscience.展开更多
The plasmon waveguide based on double chain of gold cylinders is studied using the finite-difference time-domain method （FDTD）. The wavelength of the incident Gaussian beam ranges from 650 to 1200nm, and the corresp...The plasmon waveguide based on double chain of gold cylinders is studied using the finite-difference time-domain method （FDTD）. The wavelength of the incident Gaussian beam ranges from 650 to 1200nm, and the corresponding attenuation factors are calculated. We also present a Y-splitter with 90° splitting angle, each branch in the form of double chains. The transmission efficiencies for different wavelengths are evaluated.展开更多
The quest for high spatial resolution in molecular identification is critical across various domains,including physiology,pathology,and pharmaceutical research.Super-resolution microscopy has made strides by surpassin...The quest for high spatial resolution in molecular identification is critical across various domains,including physiology,pathology,and pharmaceutical research.Super-resolution microscopy has made strides by surpassing the Abbe diffraction limit,but it relies on sophisticated equipment and is limited by the sample size to handle.Expansion microscopy,an emerging technique,has broadened the scope of subdiffraction imaging.It chemically preserves tissues at a large scale and physically enlarges them 4−20 times linearly,enabling superresolution observation.This review begins by exploring the foundational concepts of tissue clearing and the latest methodologies in the field.It then delves into the core tenets of expansion microscopy,covering a range of protocols.The review spotlights advancements in enhancing resolution,improving labeling efficiency,and ensuring isotropic tissue expansion.Finally,the review offers insights into the prospective evolution of expansion microscopy.It emphasizes the potential role of machine learning in refining image quality and in the autonomous extraction of data,which could revolutionize the way we visualize and understand biological tissues.展开更多
Terahertz(THz)microscopy has attracted attention owing to distinctive characteristics of the THz frequency region,particularly non-ionizing photon energy,spectral fingerprint,and transparency to most nonpolar material...Terahertz(THz)microscopy has attracted attention owing to distinctive characteristics of the THz frequency region,particularly non-ionizing photon energy,spectral fingerprint,and transparency to most nonpolar materials.Nevertheless,the well-known Rayleigh diffraction limit imposed on THz waves commonly constrains the resultant imaging resolution to values beyond the millimeter scale,consequently limiting the applicability in numerous emerging applications for chemical sensing and complex media imaging.In this theoretical and numerical work,we address this challenge by introducing,to our knowledge,a new imaging approach based on acquiring high-spatial frequencies by adapting the Fourier synthetic aperture approach to the THz spectral range,thus surpassing the diffractionlimited resolution.Our methodology combines multi-angle THz pulsed illumination with time-resolved field measurements,as enabled by the state-of-the-art time-domain spectroscopy technique.We demonstrate the potential of the approach for hyperspectral THz imaging of semi-transparent samples and show that the technique can reconstruct spatial and temporal features of complex inhomogeneous samples with subwavelength resolution.展开更多
Optical neural networks(ONNs)offer a promising solution for high-performance,energy-efficient artificial intelligence hardware by leveraging the parallelism and speed of light.However,the large-scale implementation of...Optical neural networks(ONNs)offer a promising solution for high-performance,energy-efficient artificial intelligence hardware by leveraging the parallelism and speed of light.However,the large-scale implementation of ONNs remains challenging due to the bulky footprint and complex control of optical synapses.In this work,we propose and simulate a plasmonic polarized synaptic architecture that overcomes the diffraction limit and enables ultra-compact ONNs.By tuning the polarization state of incident light,the optical transmittance through each plasmonic unit can be dynamically adjusted to represent a synaptic weight.Our plasmonic structures,with features as small as 40 nm,operate well below this limit in the visible spectrum(400-750 nm).Compared with diffraction and interference-based circuit designs,our proposed method achieves a substantial reduction in synaptic density by factors of 150000-fold and 1500-fold,respectively.Furthermore,we successfully demonstrate a proof-of-concept plasmonic ONN applied to the Canadian Institute for Advanced Research—10 classes(CIFAR-10)dataset using a Visual Geometry Group network with 16 layers(VGG16)model.After training for 80 epochs,the network achieves an accuracy of 93%.The polarization-tunable plasmonics paves the way towards scalable ONNs for next-generation artificial intelligence(AI)accelerators and smart sensors.展开更多
1 Mechanism of s-SNOM The concept of utilizing a near-field technique to circumvent the diffraction limit dates back to the early 20th century,proposed by Edward Synge[1].After the first demonstration of this idea,in ...1 Mechanism of s-SNOM The concept of utilizing a near-field technique to circumvent the diffraction limit dates back to the early 20th century,proposed by Edward Synge[1].After the first demonstration of this idea,in 1972 in microwaves[2]and 1984 in visible light[3,4],various practices with similar near-field approaches emerged.Hillenbrand et al.[5]recently reviewed scattering-type scanning near-field optical microscopy(s-SNOM)as a specific type of near-field scanning technique.The detection limit of this near-field scanning technique is characterized by the sharpness of the metallic tip,rather than the wavelength of the electromagnetic wave.Thus,the potential to scan with a very broad frequency range while maintaining an extremely high spatial resolution(nominally 10-100 nm)makes this proposal extremely promising.By analyzing the local dielectric constantϵ(x)as a function of scanning frequency and controlling other environmental parameters,a wealth of physical information can be extracted.展开更多
Surface plasmonic polaritons(SPPs)break Abbe's diffraction limit in the near field and provide a promising solution for high-resolution nanolithography without reducing illuminating wavelength.However,the resoluti...Surface plasmonic polaritons(SPPs)break Abbe's diffraction limit in the near field and provide a promising solution for high-resolution nanolithography without reducing illuminating wavelength.However,the resolution of the normal plasmonic lithography method based on ultraviolet exposure of a photoresist heavily relies on the size of the elaborate nanostructures,which usually require precise nanofabrication.Meanwhile,a high-cost pulsed laser is required as the light source to further reduce the lithography linewidth.Here,we establish a highresolution and low-cost scanning probe nanolithography system based on the infrared surface plasmons.An easy-fabrication probe is designed by tailoring four concentric annular slits with a moderate width of 200 nm,which couples the incident radially polarized beam into SPPs,resulting in an ultra-strong spot at the tip apex.Such superfocusing mode is demonstrated to apply to the thermal field through the optical-thermal effect so as to cause the heat accumulation with a more restricted heating area,which is utilized for the thermal probe nanolithography.Experimental results indicate that the subwavelength feature with a linewidth down to 13 nm is realized using an inexpensive 1064 nm wavelength continuous-wave laser.Our scheme shows great potential in fabrication of planar optical elements with small size and high flexibility,and can also find extensive applications in areas such as single-molecule spectra,biological detection,and optical microscopy.展开更多
基金supported by the West Light Project,CAS(xbzg-zdsys-202206)the National Key Research and Development Program of China(2021YFA1401003)+1 种基金the National Natural Science Foundation of China(NSFC)(62222513,U24A6010,and U24A20317)the Sichuan Engineering Research Center of Digital Materials.
文摘Optical monitoring of object position and alignment with nanoscale precision is critical for ultra-precision measurement applications,such as micro/nano-fabrication,weak force sensing,and micro-scopic imaging.Traditional optical nanometry methods often rely on precision nanostructure fabrication,multi-beam interferometry,or complex post-processing algorithms,which can limit their practical use.In this study,we introduced a simplified and robust quantum measurement technique with an achievable resolution of 2.2 pm and an experimental demonstration of 1 nm resolution,distinguishing it from conventional interferometry,which depended on multiple reference beams.We designed a metasurface substrate with a mode-conversion function,in which an incident Gaussian beam is converted into higher-order transverse electromagnetic mode(TEM)modes.A theoretical analysis,including calculations of the Fisher information,demonstrated that the accuracy was maintained for nanoscale displacements.In conclusion,the study findings provide a new approach for precise alignment and metrology of nanofabrication and other advanced applications.
基金supported by the National Natural Science Foundation of China(NSFC)(Nos.62174040 and 12174423)the 13th Batch of Outstanding Young Scientific and Technological Talents Project in Guizhou Province(No.[2021]5618)+1 种基金the Science and Technology Projects of Guizhou Provincial(No.ZK[2024]501)the Scientific Research Fund of Guizhou Minzu University(No.GZMUZK[2023]CXTD07).
文摘The optical manipulation of nanoparticles on superlubricity surfaces was investigated.The research revealed that,due to the near-zero static friction and extremely low dynamic friction at superlubricity interfaces,the maximum intensity for controlling the optical field can be less than 100 W/cm^(2).The controlled nanoparticle radius can be as small as 5 nm,which is more than one order of magnitude smaller than that of nanoparticles controlled through traditional optical manipulation.Manipulation can be achieved on sub-microsecond to microsecond timescales.Furthermore,the manipulation takes place on solid surfaces and in nonliquid environments,with minimal impact from Brownian motion.By appropriately increasing the dynamic friction,controlling the light intensity,or reducing the pressure,the effects of Brownian motion can be eliminated,allowing for the construction of microstructures with a size as small as 1/75 of the wavelength of light while controlling the light intensity,which is seven orders of magnitude smaller compared to manipulating nanoparticles on traditional surfaces.This enables the control of super-resolution optical microstructures.The optical super-resolution manipulation of nanoparticles on superlubricity surfaces has important applications in fields such as nanofabrication,photolithography,optical metasurfaces,and biochemical analysis.
基金supported by the National Key Research and Development Program of China (2022YFB4602600)National Natural Science Foundation of China (Grant Nos. 52425508 & 52221001)the Hunan Provincial Natural Science Foundation of China (2025JJ60286)。
文摘Lithography is a Key enabling technique in modern micro/nano scale technology.Achieving the optimal trade-off between resolution,throughput,and cost remains a central focus in the ongoing development.However,current lithographic techniques such as direct-write,projection,and extreme ultraviolet lithography achieve higher resolution at the expense of increased complexity in optical systems or the use of shorter-wavelength light sources,thus raising the overall cost of production.Here,we present a cost-effective and wafer-level perfect conformal contact lithography at the diffraction limit.By leveraging a transferable photoresist,the technique ensures optimal contact between the mask and photoresist with zero-gap,facilitating the transfer of patterns at the diffraction limit while maintaining high fidelity and uniformity across large wafers.This technique applies to a wide range of complex surfaces,including non-conductive glass surfaces,flexible substrates,and curved surfaces.The proposed technique expands the potential of contact photolithography for novel device architectures and practic al manufacturing processes.
文摘Diffraction limited electron storage ring is considered a promising candidate for future light sources,whose main characteristics are higher brilliance,better transverse coherence and better stability.The challenge of diffraction limited storage ring design is how to achieve the ultra low beam emittance with acceptable nonlinear performance.Effective linear and nonlinear parameter optimization methods based on Artificial Intelligence were developed for the storage ring physical design.As an example of application,partial physical design of HALS(Hefei Advanced Light Source),which is a diffraction limited VUV and soft X-ray light source,was introduced.Severe emittance growth due to the Intra Beam Scattering effect,which is the main obstacle to achieve ultra low emittance,was estimated quantitatively and possible cures were discussed.It is inspiring that better performance of diffraction limited storage ring can be achieved in principle with careful parameter optimization.
基金the National Natural Science Foundation of China(Nos.61775199 and 61775112).
文摘A 1178 J near diffraction limited 527 nm laser is realized in a complete closed-loop adaptive optics(AO)controlled off-axis multi-pass amplification laser system.Generated from a fiber laser and amplified by the pre-amplifier and the main amplifier,a 1053 nm laser beam with the energy of 1900 J is obtained and converted into a 527 nm laser beam by a KDP crystal with 62%conversion efficiency,1178 J and beam quality of 7.93 times the diffraction limit(DL).By using a complete closed-loop AO configuration,the static and dynamic wavefront distortions of the laser system are measured and compensated.After correction,the diameter of the circle enclosing 80%energy is improved remarkably from 7.93DL to 1.29DL.The focal spot is highly concentrated and the 1178 J,527 nm near diffraction limited laser is achieved.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11074038 and 11374051)
文摘In this paper, we extensively study the higher-order harmonic generation of the general limited diffraction m-th- order Bessel beam. The analysis is based on successive approximations of the Khokhlov-Zabolotskaya-Kuznetsov （KZK） equation. Asymptotic expansions are presented for higher-order harmonic Bessel beams in near and far fields. The validity of asymptotic approximation is also analyzed. The higher-order harmonic of the Bessel beam with the lowest zero-order is taken as a special example.
文摘Objective To investigate a new class of solutions to the isotropic/homogeneous scalar wave equation, which termed limited diffraction beams and realize ultrasonic 3D imaging. Methods Limited diffraction beams were derived. We performed the study of 3D pulse echo imaging with limited diffraction array beam. To obtain high frame rate images, a single plane wave pulse (broadband) was transmitted with the arrays. Echoes received with the same arrays were processed with Fourier method to construct 3D images. Results Compared with traditional pulse echo imaging, this method has a larger depth of field, high frame rate, and high signal to noise ratio. Conclusion The new method has prospect of high frame rate 3D imaging. In addition, the imaging system based this method is easily implemented and has high quality image.
基金Project supported by the National Basic Research Program of China(Grant No.2012CB825802)the Major Scientific Instruments Equipment Development of China(Grant No.2012YQ15009203)+1 种基金the National Natural Science Foundation of China(Grant Nos.60878053 and 11004136)the State Key Laboratory of Precision Measurement Technology and Instruments,Tsinghua University,China(Grant No.DL12-01)
文摘In the implementation of CARS nanoscopy, signal strength decreases with focal volume size decreasing. A crucial problem that remains to be solved is whether the reduced signal generated in the suppressed focal volume can be detected. Here reported is a theoretical analysis of detection limit （DL） to time-resolved CARS （T-CARS） nanoscopy based on our proposed additional probe-beam-induced phonon depletion （APIPD） method for the low concentration samples. In order to acquire a detailed shot-noise limited signal-to-noise （SNR） and the involved parameters to evaluate DL, the T-CARS process is described with full quantum theory to estimate the extreme power density levels of the pump and Stokes beams determined by saturation behavior of coherent phonons, which are both actually on the order of ~ 109 W/cm2. When the pump and Stokes intensities reach such values and the total intensity of the excitation beams arrives at a maximum tolerable by most biological samples in a certain suppressed focal volume （40-nm suppressed focal scale in APIPD method）, the DL correspondingly varies with exposure time, for example, DL values are 103 and 102 when exposure times are 20 ms and 200 ms respectively.
基金financially supported by A*STAR under IRG program(Grant No.A2083c0058)and the MTC Programmatic(Grant No.M22L1b0110)Z Wang thanks the GAP Funding(I21D1AG010)+4 种基金the CAS Project for Young Scientists in Basic Research(Grant No.YSBR-049)the National Natural Science Foundation of China(Grant Nos.12134013 and 62322512)the National Key Research and Development Program of China(Grant No.2022YFB3607300)the CAS Pioneer Hundred Talents Program,and support from the University of Science and Technology of China’s Centre for MicroNanoscale Research and Fabrication.
文摘Supercritical lens(SCL)can break the diffraction limit in the far field and has been demonstrated for high-resolution scanning confocal imaging.Its capability in sharper focusing and needle-like long focal depth should allow high-resolution lithography at violet or ultraviolet(UV)wavelength,however,this has never been experimentally demonstrated.As a proof of concept,in this paper SCLs operating at 405 nm(h-line)wavelength with smaller full-width-at-half-maximum focal spot and longer depth of focus than conventional Fresnel zone lens while maintaining controlled side lobes are designed for direct laser writing(DLW)lithography.Aluminum nitride(AlN)with a high refractive index and low loss in UVvisible range is used to fabricate nanopillar-based metasurfaces structure for the metalens.Grating arrays with improved pitch resolution are fabricated using the SCLs with sub-diffraction-limit focusing capability.The AlN-based metasurface for SCLs at short wavelength for DLW could extend further to UV or deep UV lithography and might be of great interest to both the research and industry applications.
文摘We report a comprehensive numerical study of super resolution (SR) structured illumination microscopy (SIM) utilizing the classic Heintzmann-Cremer SIM process and algorithm. In particular, we investigated the impact of the diffraction limit of the underlying imaging system on the optimal SIM grating frequency that can be used to obtain the highest SR enhancement with non-continuous spatial frequency support. Besides confirming the previous theoretical and experimental work that SR-SIM can achieve an enhancement close to 3 times the diffraction limit with grating pattern illuminations, we also observe and report a series of more subtle effects of SR-SIM with non-continuous spatial frequency support. Our simulations show that when the SIM grating frequency exceeds twice that of the diffraction limit, the higher SIM grating frequency can help achieve a higher SR enhancement for the underlying imaging systems whose diffraction limit is low, though this enhancement is obtained at the cost of losing resolution at some lower resolution targets. Our simulations also show that, for underlying imaging systems with high diffraction limits, however, SR-SIM grating frequencies above twice the diffraction limits tend to bring no significant extra enhancement. Furthermore, we observed that there exists a limit grating frequency above which the SR enhancement effect is lost, and the reconstructed images essentially have the same resolution as the one obtained directly from the underlying imaging system without using the SIM process.
基金supported by the grants from the National Natural Science Foundation of China(Nos.11174089 and 61138003)the Instrument Developing Project of the Chinese Academy of Sciences(No.YZ201263)+2 种基金the Instrument Function Developing Project of the Chinese Academy of Sciences(No.yg2012032)the Key Project of Department of Education of Guangdong Province(No.cxzd1112)Guangzhou Municipal Science and Technology Program Project(No.2012J5100004)
文摘Fluorescence microscopy has become an essential tool for biological research because it can be minimally invasive, acquire data rapidly, and target molecules of interest with specific labeling strategies. However, the diffraction-limited spatial resolution, which is classically limited to about 200 nm in the lateral direction and about 500 nm in the axial direction, hampers its application to identify delicate details of subcellular structure. Extensive efforts have been made to break diffraction limit for obtaining high-resolution imaging of a biological specimen. Various methods capable of obtaining super-resolution images with a resolution of tens of nanometers are currently available. These super-resolution techniques can be generally divided into three primary classes： （1） patterned illumination- based super-resolution imaging, which employs spatially and temporally modulated illumination light to reconstruct sub-diffraction structures; （2） single-molecule localization-based super-resolution imaging, which localizes the profile center of each individual fluo- rophore at subdiffraction precision; （3） bleaching/blinking-based super-resolution imaging. These super-resolution techniques have been utilized in different biological fields and provide novel insights into several new aspects of life science. Given unique technical merits and commercial availability of super-resolution fluorescence microscope, increasing applications of this powerful technique in life science can be expected.
基金support by the National Natural Science Foundation of China(52075410,51975483,51622509)the Fundamental Research Funds for the Central Universities(31020190504001)+3 种基金the 111 Project(B13044),the Dean Fund(2019GDYJY05)the Collaborative Innov-ation Center Project of Shaanxi Provincial Department of Education(20JY031)the Natural Science Basic Research Plan in Shaanxi Province of China(2018JQ6012)the Hong Kong Polytechnic University through the“Life Science Research”project(1-ZVH9),and the City University of Hong Kong(9610456).
文摘The imaging capability of conventional lenses is mainly limited by the diffraction of light,and the so-called superlens has been developed allowing the recovery of evanescent waves in the focal plane.However,the remarkable focusing behavi-or of the superlens is greatly confined in the near-field regime due to the exponential decay of evanescent waves.To tackle this issue,we design a waveguide metasurface-based superlens with an extraordinary quasi-far-field focusing capability beyond the diffraction limit in the present work.Specifically,we analyze the underlying physical mechanism and provide experimental verification of the proposed superlens.The metasurface superlens is formed by an array of gradient nanoslits perforated in a gold slab,and supports transverse-electric(TE)waveguide modes under linearly polar-ized illumination along the long axis of the slits.Numerical results illustrate that exciting such TE waveguide modes can modulate not only optical phase but also evanescent waves.Consequently,some high-spatial-frequency waves can con-tribute to the focusing of the superlens,leading to the quasi-far-field super-resolution focusing of light.Under 405 nm illu-mination and oil immersion,the fabricated superlens shows a focus spot of 98 nm(i.e.λ/4.13)at a focal distance of 1.49μm(i.e.3.68λ)using an oil immersion objective,breaking the diffraction limit ofλ/2.38 in the quasi-far field regime.The developed metasurface optical superlens with such extraordinary capabilities promises exciting avenues to nanolitho-graphy and ultra-small optoelectronic devices.
基金This study was partly supported by the National Key Basic Research Program of China (973 Program)under Grant No.2015CB352006the National Natural Science Foundation of China under Grants Nos.61335011 and 61405035Program for Changjiang Scholars and Innovative Research Team in University under Grant No.IRT 15R10.
文摘Optical microscopy allows us to observe the biological structures and processes within living cells.However,the spatial resolution of the optical microscopy is limited to about half of the wavelength by the light di®raction.Structured illumination microscopy(SIM),a type of new emerging super-resolution microscopy,doubles the spatial resolution by illuminating the specimen with a patterned light,and the sample and light source requirements of SIM are not as strict as the other super-resolution microscopy.In addition,SIM is easier to combine with the other imaging techniques to improve their imaging resolution,leading to the developments of diverse types of SIM.SIM has great potential to meet the various requirements of living cells imaging.Here,we review the recent developments of SIM and its combination with other imaging techniques.
基金the Zhangjiang National Innovation Demonstration Zone(ZJ2019-ZD-005)the National Natural Science Foundation of China(11874267)supported by a fellowship of the China Postdoctoral Science Foundation(2020M671169)。
文摘Fluorescence nanoscopy provides imaging techniques that overcome the diffraction-limited resolution barrier in light microscopy,thereby opening up a new area of research in biomedical imaging in fields such as neuroscience.Here,we review the foremost fluorescence nanoscopy techniques,including descriptions of their applications in elucidating protein architectures and mobility,the real-time determination of synaptic parameters involved in neural processes,three-dimensional imaging,and the tracking of nanoscale neural activity.We conclude by discussing the prospects of fluorescence nanoscopy,with a particular focus on its deployment in combination with related techniques(e.g.,machine learning)in neuroscience.
基金Supported by the National Basic Research Programme of China under Grant No 2006CB921900, the National Natural Science Foundation of China under Grant No 10604052, the Programme for New Century Excellent Talents in University, the Knowledge Innovation Project of Chinese Academy of Sciences under Gait No KGCX2-YW-103, the Programme of the Education Department of Anhui Province under Grant No 2006kj074A, the China Postdoctoral Science Foundation of China under Grant No 20060400205, the K. C. Wong Education Foundation of Hong Kong.
文摘The plasmon waveguide based on double chain of gold cylinders is studied using the finite-difference time-domain method （FDTD）. The wavelength of the incident Gaussian beam ranges from 650 to 1200nm, and the corresponding attenuation factors are calculated. We also present a Y-splitter with 90° splitting angle, each branch in the form of double chains. The transmission efficiencies for different wavelengths are evaluated.
基金the financial support from the Fundamental Research Funds for the Central Universities(Grant Nos.14380532,2024300419)Natural science foundation of Jiangsu province(Grant Nos.BK20220780,BE2022818).
文摘The quest for high spatial resolution in molecular identification is critical across various domains,including physiology,pathology,and pharmaceutical research.Super-resolution microscopy has made strides by surpassing the Abbe diffraction limit,but it relies on sophisticated equipment and is limited by the sample size to handle.Expansion microscopy,an emerging technique,has broadened the scope of subdiffraction imaging.It chemically preserves tissues at a large scale and physically enlarges them 4−20 times linearly,enabling superresolution observation.This review begins by exploring the foundational concepts of tissue clearing and the latest methodologies in the field.It then delves into the core tenets of expansion microscopy,covering a range of protocols.The review spotlights advancements in enhancing resolution,improving labeling efficiency,and ensuring isotropic tissue expansion.Finally,the review offers insights into the prospective evolution of expansion microscopy.It emphasizes the potential role of machine learning in refining image quality and in the autonomous extraction of data,which could revolutionize the way we visualize and understand biological tissues.
基金Agence Nationale de la Recherche(ANR-22-CE42-0005-HYPSTER,ANR 22-PEEL-0003-Comptera)。
文摘Terahertz(THz)microscopy has attracted attention owing to distinctive characteristics of the THz frequency region,particularly non-ionizing photon energy,spectral fingerprint,and transparency to most nonpolar materials.Nevertheless,the well-known Rayleigh diffraction limit imposed on THz waves commonly constrains the resultant imaging resolution to values beyond the millimeter scale,consequently limiting the applicability in numerous emerging applications for chemical sensing and complex media imaging.In this theoretical and numerical work,we address this challenge by introducing,to our knowledge,a new imaging approach based on acquiring high-spatial frequencies by adapting the Fourier synthetic aperture approach to the THz spectral range,thus surpassing the diffractionlimited resolution.Our methodology combines multi-angle THz pulsed illumination with time-resolved field measurements,as enabled by the state-of-the-art time-domain spectroscopy technique.We demonstrate the potential of the approach for hyperspectral THz imaging of semi-transparent samples and show that the technique can reconstruct spatial and temporal features of complex inhomogeneous samples with subwavelength resolution.
基金supported in part by the National Natural Science Foundation of China(Grant Nos.62371095,62201096,62401276)by the Natural Science Research Start-up Foundation of Recruiting Talents of Nanjing University of Posts and Telecommunications(Grant No.NY223161)+4 种基金in part by the Jiangsu Provincial Key Research and Development Program(Grant No.BE2022126)the Key R&D Program of Sichuan Province(Grant No.2022ZHCG0041)the National Key Research and Development Program of China(Grant No.2022YFB3206100)the Natural Science Foundation of Sichuan Province(Grant No.2024NSFSC0509)the China Postdoctoral Science Foundation(Grant Nos.2024T170097,2024M760343).
文摘Optical neural networks(ONNs)offer a promising solution for high-performance,energy-efficient artificial intelligence hardware by leveraging the parallelism and speed of light.However,the large-scale implementation of ONNs remains challenging due to the bulky footprint and complex control of optical synapses.In this work,we propose and simulate a plasmonic polarized synaptic architecture that overcomes the diffraction limit and enables ultra-compact ONNs.By tuning the polarization state of incident light,the optical transmittance through each plasmonic unit can be dynamically adjusted to represent a synaptic weight.Our plasmonic structures,with features as small as 40 nm,operate well below this limit in the visible spectrum(400-750 nm).Compared with diffraction and interference-based circuit designs,our proposed method achieves a substantial reduction in synaptic density by factors of 150000-fold and 1500-fold,respectively.Furthermore,we successfully demonstrate a proof-of-concept plasmonic ONN applied to the Canadian Institute for Advanced Research—10 classes(CIFAR-10)dataset using a Visual Geometry Group network with 16 layers(VGG16)model.After training for 80 epochs,the network achieves an accuracy of 93%.The polarization-tunable plasmonics paves the way towards scalable ONNs for next-generation artificial intelligence(AI)accelerators and smart sensors.
文摘1 Mechanism of s-SNOM The concept of utilizing a near-field technique to circumvent the diffraction limit dates back to the early 20th century,proposed by Edward Synge[1].After the first demonstration of this idea,in 1972 in microwaves[2]and 1984 in visible light[3,4],various practices with similar near-field approaches emerged.Hillenbrand et al.[5]recently reviewed scattering-type scanning near-field optical microscopy(s-SNOM)as a specific type of near-field scanning technique.The detection limit of this near-field scanning technique is characterized by the sharpness of the metallic tip,rather than the wavelength of the electromagnetic wave.Thus,the potential to scan with a very broad frequency range while maintaining an extremely high spatial resolution(nominally 10-100 nm)makes this proposal extremely promising.By analyzing the local dielectric constantϵ(x)as a function of scanning frequency and controlling other environmental parameters,a wealth of physical information can be extracted.
基金National Key Research&Development Program of China(2023YFB3811400)Young Scientists Fund of National Natural Science Foundation of China(52303368)Financial Program of BJAST(25CE-YS-05,25CB011-03)。
文摘Surface plasmonic polaritons(SPPs)break Abbe's diffraction limit in the near field and provide a promising solution for high-resolution nanolithography without reducing illuminating wavelength.However,the resolution of the normal plasmonic lithography method based on ultraviolet exposure of a photoresist heavily relies on the size of the elaborate nanostructures,which usually require precise nanofabrication.Meanwhile,a high-cost pulsed laser is required as the light source to further reduce the lithography linewidth.Here,we establish a highresolution and low-cost scanning probe nanolithography system based on the infrared surface plasmons.An easy-fabrication probe is designed by tailoring four concentric annular slits with a moderate width of 200 nm,which couples the incident radially polarized beam into SPPs,resulting in an ultra-strong spot at the tip apex.Such superfocusing mode is demonstrated to apply to the thermal field through the optical-thermal effect so as to cause the heat accumulation with a more restricted heating area,which is utilized for the thermal probe nanolithography.Experimental results indicate that the subwavelength feature with a linewidth down to 13 nm is realized using an inexpensive 1064 nm wavelength continuous-wave laser.Our scheme shows great potential in fabrication of planar optical elements with small size and high flexibility,and can also find extensive applications in areas such as single-molecule spectra,biological detection,and optical microscopy.
