Liquid crystal Pacharatnam-Berry phase optical elements(PBOEs)have found promising applications in augmented reality and virtual reality because of their slim formfactor,lightweight,and high optical efficiency.However...Liquid crystal Pacharatnam-Berry phase optical elements(PBOEs)have found promising applications in augmented reality and virtual reality because of their slim formfactor,lightweight,and high optical efficiency.However,chromatic aberration remains a serious longstanding problem for diffractive optics,hindering their broader adoption.To overcome the chromatic aberrations for red,green and blue(RGB)light sources,in this paper,we propose a counterintuitive multi-twist structure to achieve narrowband PBOEs without crosstalk,which plays a vital role to eliminate the chromatic aberration.The performance of our designed and fabricated narrowband Pacharatnam-Berry lenses(PBLs)aligns well with our simulation results.Furthermore,in a feasibility demonstration experiment using a laser projector,our proposed PBL system indeed exhibits a diminished chromatic aberration as compared to a broadband PBL.Additionally,polarization raytracing is implemented to demonstrate the versatility of the multi-twist structure for designing any RGB wavelengths with high contrast ratios.This analysis explores the feasibility of using RGB laser lines and quantum dot light-emitting diodes.Overall,our approach enables high optical efficiency,low fabrication complexity,and high degree of design freedom to accommodate any liquid crystal material and RGB light sources,holding immense potential for widespread applications of achromatic PBOEs.展开更多
Imaging polarimetry is one of the most widely used analytical technologies for object detection and analysis.To date,most metasurface-based polarimetry techniques are severely limited by narrow operating bandwidths an...Imaging polarimetry is one of the most widely used analytical technologies for object detection and analysis.To date,most metasurface-based polarimetry techniques are severely limited by narrow operating bandwidths and inevitable crosstalk,leading to detrimental effects on imaging quality and measurement accuracy.Here,we propose a crosstalkfree broadband achromatic full Stokes imaging polarimeter consisting of polarization-sensitive dielectric metalenses,implemented by the principle of polarization-dependent phase optimization.Compared with the single-polarization optimization method,the average crosstalk has been reduced over three times under incident light with arbitrary polarization ranging from 9μm to 12μm,which guarantees the measurement of the polarization state more precisely.The experimental results indicate that the designed polarization-sensitive metalenses can effectively eliminate the chromatic aberration with polarization selectivity and negligible crosstalk.The measured average relative errors are 7.08%,8.62%,7.15%,and 7.59%at 9.3,9.6,10.3,and 10.6μm,respectively.Simultaneously,the broadband full polarization imaging capability of the device is also verified.This work is expected to have potential applications in wavefront detection,remote sensing,light-field imaging,and so forth.展开更多
Camouflage is one of the most widespread and powerful strategies that animals use to make detection/recognition more difficult. Many orb-web spiders of the genus Cyclosa add prey remains, plant debris, moults, and/or ...Camouflage is one of the most widespread and powerful strategies that animals use to make detection/recognition more difficult. Many orb-web spiders of the genus Cyclosa add prey remains, plant debris, moults, and/or eggsacs to their webs called web decorations. Web decorations resembling spider body colour pattern have been considered to camouflage the spider from predators. While this camouflage is obvious from a human＇s perspective, it has rarely been investigated from a predator＇s perspective. In this study, we tested the visibility of web decorations by calculating chromatic and achromatic contrasts of detritus and eggsae decorations built by Cyclosa octotubereulata, against four different backgrounds viewed by both bird （e.g., blue tits） and hymenopteran （e.g. wasps） predators. We showed that both juvenile and adult spiders on webs with detritus or egg-sac deco- rations were undetectable by both hymenopteran and bird predators over short and long distances. Our results thus suggest that decorating webs with detritus or eggsacs by C octotuberculata may camouflage the spiders from both hymenopteran and bird predators in their common habitats [Current Zoology 56 （3）： 379-387, 2010].展开更多
Based on the phase-change material Ge_(2)Sb_(2)Te_(5)(GST),achromatic metasurface optical device in the longer-infrared wavelength is designed.With the combination of the linear phase gradient GST nanopillar and the a...Based on the phase-change material Ge_(2)Sb_(2)Te_(5)(GST),achromatic metasurface optical device in the longer-infrared wavelength is designed.With the combination of the linear phase gradient GST nanopillar and the adjustment of the crystalline fraction m value of GST,the polarization insensitive achromic metalenses and beam deflector metasurface within the longer-infrared wavelength 9.5μm to 13μm are realized.The design results show that the achromatic metalenses can be focused on the same focal plane within the working waveband.The simulation calculation results show that the fullwidth at half-maximum(FWHM)of the focusing spot reaches the diffraction limit at each wavelength.In addition,the same method is also used to design a broadband achromatic beam deflector metasurface with the same deflection angle of 19°.The method proposed in this article not only provides new ideas for the design of achromatic metasurfaces,but also provides new possibilities for the integration of optical imaging,optical coding and other related optical systems.展开更多
Metasurfaces are densely arrayed two⁃dimensional(2D)artificial planar metamaterials,which can manipulate the polarization,distribution,and amplitude of light by accurately controlling the phase of the scattering light...Metasurfaces are densely arrayed two⁃dimensional(2D)artificial planar metamaterials,which can manipulate the polarization,distribution,and amplitude of light by accurately controlling the phase of the scattering light.The flat metasurface has the potential to substantially reduce the thickness and complexity of the structures and allows ease of fabrication and integration into devices.However,the inherent chromatic aberration of the metasurface originating from the resonant dispersion of the antennas and the intrinsic chromatic dispersion limit their quality.How to effectively suppress or manipulate the chromatic aberration of metalenses has attracted worldwide attention in the last few years,leading to a variety of excellent achievements.Furthermore,utilizing the chromatic dispersion of metasurface to realize special functionalities is also of significant importance.In this review,the most promising recent examples of chromatic dispersion manipulation based on optical metasurface materials are highlighted and put into perspective.展开更多
In recent years,a new generation of storage ring-based light sources,known as diffraction-limited storage rings(DLSRs),whose emittance approaches the diffraction limit for the range of X-ray wavelengths of interest to...In recent years,a new generation of storage ring-based light sources,known as diffraction-limited storage rings(DLSRs),whose emittance approaches the diffraction limit for the range of X-ray wavelengths of interest to the scientific community,has garnered significant attention worldwide.Researchers have begun to design and build DLSRs.Among various DLSR proposals,the hybrid multibend achromat(H-MBA)lattice enables sextupole strengths to be maintained at a reasonable level when minimizing the emittance;hence,it has been adopted in many DLSR designs.Based on the H-7BA lattice,the design of the Advanced Photon Source Upgrade Project(APS-U)can effectively reduce emittance by replacing six quadrupoles with anti-bends.Herein,we discuss the feasibility of designing an APS-U-type H-MBA lattice for the Southern Advanced Photon Source,a mid-energy DLSR light source with ultralow emittance that has been proposed to be built adjacent to the China Spallation Neutron Source.Both linear and nonlinear dynamics are optimized to obtain a detailed design of this type of lattice.The emittance is minimized,while a sufficiently large dynamic aperture(DA)and momentum acceptance(MA)are maintained.A design comprising 36 APS-U type H-7BAs,with an energy of 3 GeV and a circumference of 972 m,is achieved.The horizontal natural emittance is 20 pm·rad,with a horizontal DA of 5.8 mm,a vertical DA of 4.5 mm,and an MA of 4%,as well as a long longitudinal damping time of 120 ms.Subsequently,a few modifications are performed based on the APS-U-type lattice to reduce the maximum value of damping time from 120 to 44 ms while maintaining other performance parameters at the same level.展开更多
Metalenses are two-dimensional planar metamaterial lenses, which have the advantages of high efficiency and easy integration. However, most metalenses cannot modulate the light intensity, which limits their applicatio...Metalenses are two-dimensional planar metamaterial lenses, which have the advantages of high efficiency and easy integration. However, most metalenses cannot modulate the light intensity, which limits their applications. To deal with it, taking advantage of flexible regulation of the beam amplitude and phase by the metalens, the geometric phase method is selected to design the dual-function metalens. It can effectively eliminate chromatic aberration in a visible light band from 535 nm to 600 nm and achieve amplitude modulation. After transmitting the metalens, the amplitudes of the beam respectively turn into 0.2 and 0.9. In this way, the amount of transmission of metalens in the preset band can be quantitatively controlled. According to the distribution characteristics of light diffraction intensity, the metalens designed can play a dual modulation role of achromatism and interference double-beam equilibrium in the paper, to meet the needs of miniaturization and integration of the optical system. The achromatic and amplitude-modulated metalens will have great application potential in optical holographic imaging and super-resolution focusing.展开更多
On-chip focusing of plasmons in graded-index lenses is important for imaging,lithography,signal processing,and optical interconnects at the deep subwavelength nanoscale.However,owing to the inherent strong wavelength ...On-chip focusing of plasmons in graded-index lenses is important for imaging,lithography,signal processing,and optical interconnects at the deep subwavelength nanoscale.However,owing to the inherent strong wavelength dispersion of plasmonic materials,the on-chip focusing of plasmons suffers from severe chromatic aberrations.With the well-established planar dielectric grating,a graded-index waveguide array lens(GIWAL)is proposed to support the excitation and propagation of acoustic graphene plasmon polaritons(AGPPs)and to achieve the achromatic on-chip focusing of the AGPPs with a focus as small as about 2%of the operating wavelength in the frequency band from 10 to 20 THz,benefiting from the wavelength-independent index profile of the GIWAL.An analytical theory is provided to understand the on-chip focusing of the AGPPs and other beam evolution behaviors,such as self-focusing,self-collimation,and pendulum effects of Gaussian beams as well as spatial inversions of digital optical signals.Furthermore,the possibility of the GIWAL to invert spatially broadband digital optical signals is demonstrated,indicating the potential value of the GIWAL in broadband digital communication and signal processing.展开更多
Achromatic patches are a common element of plumage patterns in many bird species and there is growing body of evidence that in many avian taxa they can play a signaling role in mate choice.Although the blue tit Cyanis...Achromatic patches are a common element of plumage patterns in many bird species and there is growing body of evidence that in many avian taxa they can play a signaling role in mate choice.Although the blue tit Cyanistes caeruleus is a well-established model species in the studies on coloration,its white wing patch has never been examined in the context of sex-specific trait expression.In this exploratory study,we examined sexual size dimorphism and dichromatism of greater covert’s dots creating white wing patch and analyzed its correlations with current body condition and crown coloration—a trait with established role in sexual selection.Further,we qualitatively analyzed microstructural barb morphology underlying covert’s coloration.We found significant sexual dimorphism in the dot size independent of covert size and sexual dichromatism in both white dot and blue outer covert’s vane spectral characteristics.Internal structure of covert barbs within the white dot was similar to the one found in barbs from the blue part that is,with a medullary area consisting of dead keratinocytes containing channel-typeß-keratin spongy nanostructure and centrally located air cavities.However,it lacked melanosomes which was the main observed difference.Importantly,UV chroma of covert’s blue vane was positively correlated with crown UV chroma and current condition(the latter only in males),which should be a premise for further research on the signal function of the wing stripe.展开更多
Metalenses with achromatic performance offer a new opportunity for high-quality imaging with an ultracompact configuration;however,they suffer from complex fabrication processes and low focusing efficiency.In this stu...Metalenses with achromatic performance offer a new opportunity for high-quality imaging with an ultracompact configuration;however,they suffer from complex fabrication processes and low focusing efficiency.In this study,we propose an efficient design method for achromatic microlenses on a wavelength scale using materials with low dispersion,an adequately designed convex surface,and a thickness profile distribution.By taking into account the absolute chromatic aberration,relative focal length shift(FLS),and numerical aperture(NA),microlens with a certain focal length can be realized through our realized map of geometric features.Accordingly,the designed achromatic microlenses with low-dispersion fused silica were fabricated using a focused ion beam,and precise surface profiles were obtained.The fabricated microlenses exhibited a high average focusing efficiency of 65%at visible wavelengths of 410-680 nm and excellent achromatic capability via white light imaging.Moreover,the design exhibited the advantages of being polarization-insensitive and near-diffraction-limited.These results demonstrate the effectiveness of our proposed achromatic microlens design approach,which expands the prospects of miniaturized optics such as virtual and augmented reality,ultracompact microscopes,and biological endoscopy.展开更多
Diffractive lenses(DLs)can realize high-resolution imaging with light weight and compact size.Conventional DLs suffer large chromatic and off-axis aberrations,which significantly limits their practical applications.Al...Diffractive lenses(DLs)can realize high-resolution imaging with light weight and compact size.Conventional DLs suffer large chromatic and off-axis aberrations,which significantly limits their practical applications.Although many achromatic methods have been proposed,most of them are used for designing small aperture DLs,which have low diffraction efficiencies.In the designing of diffractive achromatic lenses,increasing the aperture and improving the diffraction efficiency have become two of the most important design issues.Here,a novel phase-coded diffractive lens(PCDL)for achromatic imaging with a large aperture and high efficiency is proposed and demonstrated experimentally,and it also possesses wide field-of-view(FOV)imaging at the same time.The phase distribution of the conventional phase-type diffractive lens(DL)is coded with a cubic function to expand both the working bandwidth and the FOV of conventional DL.The proposed phase-type DL is fabricated by using the laser direct writing of grey-scale patterns for a PCDL of a diameter of 10 mm,a focal length of 100 mm,and a cubic phase coding parameter of 30π.Experimental results show that the working bandwidth and the FOV of the PCDL respectively reach 50 nm and 16°with over 8%focusing efficiency,which are in significant contrast to the counterparts of conventional DL and in good agreement with the theoretical predictions.This work provides a novel way for implementing the achromatic,wide FOV,and high-efficiency imaging with large aperture DL.展开更多
Adaptive mate choice has been accepted as the leading theory to explain the colorful plumage of birds.This theory hypothesizes that conspicuous colors act as signals to advertise the qualities of the owners.However,a ...Adaptive mate choice has been accepted as the leading theory to explain the colorful plumage of birds.This theory hypothesizes that conspicuous colors act as signals to advertise the qualities of the owners.However,a dilemma arises in that conspicuous colors may not only attract mates,but also alert predators.The"private channels of communication"hypothesis proposes that some intraspecific signals may not be visible to heterospecific animals because of different visual systems.To better understand the evolution of plumage colors and sexual selection in birds,here we studied the chromatic difference and achromatic differences of melanin-and carotenoid-based plumage coloration in five minivet species(Pericrocotus spp.)under conspecific and predator visual systems.We found that either the chromatic or achromatic difference among male or female minivets’plumage was consistently higher under conspecific vision than under predator vision for all five studied species of minivets.This result indicated that individual differences in plumage colors of minivets were visible to the conspecific receivers and hidden from potential predators as a result of evolution under predation risk and conspecific communication.However,males were under a higher risk of predation because they were more conspicuous than females to the vision of a nocturnal predator.展开更多
Metasurfaces have emerged as a flexible platform for shaping the electromagnetic field via the tailoring phase,amplitude,and polarization at will.However,the chromatic aberration inherited from building blocks’diffra...Metasurfaces have emerged as a flexible platform for shaping the electromagnetic field via the tailoring phase,amplitude,and polarization at will.However,the chromatic aberration inherited from building blocks’diffractive nature plagues them when used in many practical applications.Current solutions for eliminating chromatic aberration usually rely on searching through many meta-atoms to seek designs that satisfy both phase and phase dispersion preconditions,inevitably leading to intensive design efforts.Moreover,most schemes are commonly valid for incidence with a specific spin state.Here,inspired by the Rayleigh criterion for spot resolution,we present a design principle for broadband achromatic and polarization-insensitive metalenses using two sets of anisotropic nanofins based on phase change material Ge2Sb2Se4Te1.By limiting the rotation angles of all nanofins to either 0 deg or 90 deg,the metalens with a suitable numerical aperture constructed by this fashion allows for achromatic and polarization-insensitive performance across the wavelength range of 4–5μm,while maintaining high focusing efficiency and diffraction-limited performance.We also demonstrate the versatility of our approach by successfully implementing the generation of broadband achromatic and polarization-insensitive focusing optical vortex.This work represents a major advance in achromatic metalenses and may find more applications in compact and chip-scale devices.展开更多
A new achromatic phase retarder based on a metal-multilayer dielectric grating structure is designed using the rigorous coupled wave analysis method and the genetic algorithm.The optimized phase retarder can maintain ...A new achromatic phase retarder based on a metal-multilayer dielectric grating structure is designed using the rigorous coupled wave analysis method and the genetic algorithm.The optimized phase retarder can maintain phase retardation around 90°from 900 nm to 1200 nm,and the maximum deviation is less than 4.5%while the diffraction efficiencies of TE and TM waves are both higher than 95%.Numerical analysis shows the designed phase retarder has a high fabrication tolerance of groove depth,duty cycle and incident angle.This achromatic phase retarder is simple in design and stable in performance,and can be widely used in optical systems.展开更多
A new doubly achromatic two-magnet beam bending system is described.Itconsists of two nonuniform dipoles separated by a small drift space.Some doublyachromatic relations are derived.The system showed excellent achroma...A new doubly achromatic two-magnet beam bending system is described.Itconsists of two nonuniform dipoles separated by a small drift space.Some doublyachromatic relations are derived.The system showed excellent achromatic and focusingproperties and good quality of electron beam with small diameter.Very small diver-gence and axial symmetry were produced at the output of the system.The system isspecially suitable for low energy electron linac beam with large energy spread.展开更多
A new strategy has been presented to overcome the long-term dilemma of simultaneously achieving high numerical aperture,large aperture size,and broadband achromatism of flat lenses.A stepwise phase dispersion compensa...A new strategy has been presented to overcome the long-term dilemma of simultaneously achieving high numerical aperture,large aperture size,and broadband achromatism of flat lenses.A stepwise phase dispersion compensation(SPDC)layer is introduced as a substrate on which the meta-atoms are positioned.展开更多
Augmented reality(AR)displays are emerging as the next generation of interactive platform,providing deeper humandigital interactions and immersive experiences beyond traditional flat-panel displays.Diffractive wavegui...Augmented reality(AR)displays are emerging as the next generation of interactive platform,providing deeper humandigital interactions and immersive experiences beyond traditional flat-panel displays.Diffractive waveguide is a promising optical combiner technology for AR owing to its potential for the slimmest geometry and lightest weight.However,severe chromatic aberration of diffractive coupler has constrained widespread adoption of diffractive waveguide.Wavelength-dependent light deflection,caused by dispersion in both in-coupling and out-coupling processes,results in limited full-color field of view(FOV)and nonuniform optical responses in color and angular domains.Here we introduce an innovative full-color AR system that overcomes this long-standing challenge of chromatic aberration using a combination of inverse-designed metasurface couplers and a high refractive index waveguide.The optimized metasurface couplers demonstrate true achromatic behavior across the maximum FOV supported by the waveguide(exceeding 45°).Our AR prototype based on the designed metasurface waveguide,exhibits superior color accuracy and uniformity.This unique achromatic metasurface waveguide technology is expected to advance the development of visually compelling experience in compact AR display systems.展开更多
Traditionally,magic cube configurations,which have been employed to mechanically execute diverse and unconventional structural transformations,are capable of significantly boosting versatile electromagnetic responses ...Traditionally,magic cube configurations,which have been employed to mechanically execute diverse and unconventional structural transformations,are capable of significantly boosting versatile electromagnetic responses of reconfigurable metamaterials.However,this idea is still in the initial exploration stage and faces many constraints.Here,we propose magic cube metamaterials with features of high transparency,multi-gradient phase distribution,full polarization,and high information,which manifest 47.58% optical transmittance,a 6-order phase distribution,a 77% fractional operating bandwidth,and 65.23 times information entropy of their planar counterparts.The reflection phase corresponding to coplanar lattice of the metamaterials can be dynamically and omni-directionally controlled via altering their spatial distributions through individually addressing each rotatable meta-particle while maintaining the polarization states.The optically transparent design allows for real-time visual interaction and sequence mapping of the reconfigurable metamaterials.As two proof-of-concept meta-devices,an achromatic metalens with an unchanged focal length and a switchable multi-functional beam generator is demonstrated by simulations and experiments in an ultra-wide band(8.0-18.0 GHz).This work provides an effective alternative for designing reconfigurable metamaterials with high information-entropy properties,paving a new route toward advanced equipment such as active signal processors and information encryption/decryption systems.展开更多
Since flat optics has the feature to implement a compact system,they are widely used in various applications to replace bulky refractive optics.However,they suffer from chromatic aberrations due to dispersion,limiting...Since flat optics has the feature to implement a compact system,they are widely used in various applications to replace bulky refractive optics.However,they suffer from chromatic aberrations due to dispersion,limiting their effectiveness to a narrow wavelength range.Consequently,diffractive optics has been applied for dynamic beam steering within a specific wavelength region or for static steering across multiple wavelengths.This limitation has made it challenging to implement dynamic beam steering in full-color display applications.To address this issue,we developed a multi-wavelength-based optical architecture that mitigates chromatic aberrations.This system incorporates color-selective retarders,half-wave plates,polarization plates,and beam deflectors.We experimentally demonstrated an achromatic beam deflector using a dynamic phase array in transmission mode,achieving continuous tunable beam steering over multiple wavelengths at 460,520,and 638 nm.展开更多
Introduction of the stepwise phase dispersion compensation layer allowed broadband achromatic metalens to have a high numerical aperture,which enabled high-resolution metalens imaging.
基金supports from the National Key Research and Development Program of China(2023YFB2806803)the National Natural Science Foundation of China(62075127).
文摘Liquid crystal Pacharatnam-Berry phase optical elements(PBOEs)have found promising applications in augmented reality and virtual reality because of their slim formfactor,lightweight,and high optical efficiency.However,chromatic aberration remains a serious longstanding problem for diffractive optics,hindering their broader adoption.To overcome the chromatic aberrations for red,green and blue(RGB)light sources,in this paper,we propose a counterintuitive multi-twist structure to achieve narrowband PBOEs without crosstalk,which plays a vital role to eliminate the chromatic aberration.The performance of our designed and fabricated narrowband Pacharatnam-Berry lenses(PBLs)aligns well with our simulation results.Furthermore,in a feasibility demonstration experiment using a laser projector,our proposed PBL system indeed exhibits a diminished chromatic aberration as compared to a broadband PBL.Additionally,polarization raytracing is implemented to demonstrate the versatility of the multi-twist structure for designing any RGB wavelengths with high contrast ratios.This analysis explores the feasibility of using RGB laser lines and quantum dot light-emitting diodes.Overall,our approach enables high optical efficiency,low fabrication complexity,and high degree of design freedom to accommodate any liquid crystal material and RGB light sources,holding immense potential for widespread applications of achromatic PBOEs.
基金Sichuan Science and Technology Program(2020YFJ0001)the National Natural Science Foundation of China(61975210,62222513)+1 种基金National Key Research and Development Program(SQ2021YFA1400121)China Postdoctoral Science Foundation(2021T140670)
文摘Imaging polarimetry is one of the most widely used analytical technologies for object detection and analysis.To date,most metasurface-based polarimetry techniques are severely limited by narrow operating bandwidths and inevitable crosstalk,leading to detrimental effects on imaging quality and measurement accuracy.Here,we propose a crosstalkfree broadband achromatic full Stokes imaging polarimeter consisting of polarization-sensitive dielectric metalenses,implemented by the principle of polarization-dependent phase optimization.Compared with the single-polarization optimization method,the average crosstalk has been reduced over three times under incident light with arbitrary polarization ranging from 9μm to 12μm,which guarantees the measurement of the polarization state more precisely.The experimental results indicate that the designed polarization-sensitive metalenses can effectively eliminate the chromatic aberration with polarization selectivity and negligible crosstalk.The measured average relative errors are 7.08%,8.62%,7.15%,and 7.59%at 9.3,9.6,10.3,and 10.6μm,respectively.Simultaneously,the broadband full polarization imaging capability of the device is also verified.This work is expected to have potential applications in wavefront detection,remote sensing,light-field imaging,and so forth.
基金supported by a grant from NSFC (30770332)The Ministry of Education (MOE) Academic Research Fund (AcRF)(R-154-000-335-112)
文摘Camouflage is one of the most widespread and powerful strategies that animals use to make detection/recognition more difficult. Many orb-web spiders of the genus Cyclosa add prey remains, plant debris, moults, and/or eggsacs to their webs called web decorations. Web decorations resembling spider body colour pattern have been considered to camouflage the spider from predators. While this camouflage is obvious from a human＇s perspective, it has rarely been investigated from a predator＇s perspective. In this study, we tested the visibility of web decorations by calculating chromatic and achromatic contrasts of detritus and eggsae decorations built by Cyclosa octotubereulata, against four different backgrounds viewed by both bird （e.g., blue tits） and hymenopteran （e.g. wasps） predators. We showed that both juvenile and adult spiders on webs with detritus or egg-sac deco- rations were undetectable by both hymenopteran and bird predators over short and long distances. Our results thus suggest that decorating webs with detritus or eggsacs by C octotuberculata may camouflage the spiders from both hymenopteran and bird predators in their common habitats [Current Zoology 56 （3）： 379-387, 2010].
基金Project supported by the Natural Science Foundation of Shaanxi Province,China(Grant No.2021JM466)
文摘Based on the phase-change material Ge_(2)Sb_(2)Te_(5)(GST),achromatic metasurface optical device in the longer-infrared wavelength is designed.With the combination of the linear phase gradient GST nanopillar and the adjustment of the crystalline fraction m value of GST,the polarization insensitive achromic metalenses and beam deflector metasurface within the longer-infrared wavelength 9.5μm to 13μm are realized.The design results show that the achromatic metalenses can be focused on the same focal plane within the working waveband.The simulation calculation results show that the fullwidth at half-maximum(FWHM)of the focusing spot reaches the diffraction limit at each wavelength.In addition,the same method is also used to design a broadband achromatic beam deflector metasurface with the same deflection angle of 19°.The method proposed in this article not only provides new ideas for the design of achromatic metasurfaces,but also provides new possibilities for the integration of optical imaging,optical coding and other related optical systems.
基金National Program on Key Basic Research Project of China(Grant No.2017YFA0303700)the National Natural Science Foundation of China(Grant Nos.11621091,11822406,11774164,11834007 and 11774162)。
文摘Metasurfaces are densely arrayed two⁃dimensional(2D)artificial planar metamaterials,which can manipulate the polarization,distribution,and amplitude of light by accurately controlling the phase of the scattering light.The flat metasurface has the potential to substantially reduce the thickness and complexity of the structures and allows ease of fabrication and integration into devices.However,the inherent chromatic aberration of the metasurface originating from the resonant dispersion of the antennas and the intrinsic chromatic dispersion limit their quality.How to effectively suppress or manipulate the chromatic aberration of metalenses has attracted worldwide attention in the last few years,leading to a variety of excellent achievements.Furthermore,utilizing the chromatic dispersion of metasurface to realize special functionalities is also of significant importance.In this review,the most promising recent examples of chromatic dispersion manipulation based on optical metasurface materials are highlighted and put into perspective.
基金This work was supported by the National Natural Science Foundation of China(No.11922512)the Youth Innovation Promotion Association of Chinese Academy of Sciences(No.Y201904)the Guangdong Basic and Applied Basic Research Foundation—Guangdong Dongguan Joint Foundation(No.2019B1515120069).
文摘In recent years,a new generation of storage ring-based light sources,known as diffraction-limited storage rings(DLSRs),whose emittance approaches the diffraction limit for the range of X-ray wavelengths of interest to the scientific community,has garnered significant attention worldwide.Researchers have begun to design and build DLSRs.Among various DLSR proposals,the hybrid multibend achromat(H-MBA)lattice enables sextupole strengths to be maintained at a reasonable level when minimizing the emittance;hence,it has been adopted in many DLSR designs.Based on the H-7BA lattice,the design of the Advanced Photon Source Upgrade Project(APS-U)can effectively reduce emittance by replacing six quadrupoles with anti-bends.Herein,we discuss the feasibility of designing an APS-U-type H-MBA lattice for the Southern Advanced Photon Source,a mid-energy DLSR light source with ultralow emittance that has been proposed to be built adjacent to the China Spallation Neutron Source.Both linear and nonlinear dynamics are optimized to obtain a detailed design of this type of lattice.The emittance is minimized,while a sufficiently large dynamic aperture(DA)and momentum acceptance(MA)are maintained.A design comprising 36 APS-U type H-7BAs,with an energy of 3 GeV and a circumference of 972 m,is achieved.The horizontal natural emittance is 20 pm·rad,with a horizontal DA of 5.8 mm,a vertical DA of 4.5 mm,and an MA of 4%,as well as a long longitudinal damping time of 120 ms.Subsequently,a few modifications are performed based on the APS-U-type lattice to reduce the maximum value of damping time from 120 to 44 ms while maintaining other performance parameters at the same level.
基金supported by the National Natural Science Foundation of China (No.11874184)。
文摘Metalenses are two-dimensional planar metamaterial lenses, which have the advantages of high efficiency and easy integration. However, most metalenses cannot modulate the light intensity, which limits their applications. To deal with it, taking advantage of flexible regulation of the beam amplitude and phase by the metalens, the geometric phase method is selected to design the dual-function metalens. It can effectively eliminate chromatic aberration in a visible light band from 535 nm to 600 nm and achieve amplitude modulation. After transmitting the metalens, the amplitudes of the beam respectively turn into 0.2 and 0.9. In this way, the amount of transmission of metalens in the preset band can be quantitatively controlled. According to the distribution characteristics of light diffraction intensity, the metalens designed can play a dual modulation role of achromatism and interference double-beam equilibrium in the paper, to meet the needs of miniaturization and integration of the optical system. The achromatic and amplitude-modulated metalens will have great application potential in optical holographic imaging and super-resolution focusing.
基金supported in part by the National Natural Science Foundation of China(Grant No.62105376)the Guangdong Zhujiang Project(Grant Nos.2021ZT09X070 and 2021QN02X488).The authors declare no competing financial interests。
文摘On-chip focusing of plasmons in graded-index lenses is important for imaging,lithography,signal processing,and optical interconnects at the deep subwavelength nanoscale.However,owing to the inherent strong wavelength dispersion of plasmonic materials,the on-chip focusing of plasmons suffers from severe chromatic aberrations.With the well-established planar dielectric grating,a graded-index waveguide array lens(GIWAL)is proposed to support the excitation and propagation of acoustic graphene plasmon polaritons(AGPPs)and to achieve the achromatic on-chip focusing of the AGPPs with a focus as small as about 2%of the operating wavelength in the frequency band from 10 to 20 THz,benefiting from the wavelength-independent index profile of the GIWAL.An analytical theory is provided to understand the on-chip focusing of the AGPPs and other beam evolution behaviors,such as self-focusing,self-collimation,and pendulum effects of Gaussian beams as well as spatial inversions of digital optical signals.Furthermore,the possibility of the GIWAL to invert spatially broadband digital optical signals is demonstrated,indicating the potential value of the GIWAL in broadband digital communication and signal processing.
基金supported by“the National Science Centre”to K.J.grant no.UMO-2015/19/N/NZ8/00404to S.M.D grant no.UMO-2015/18/E/NZ8/00505.Long-term study of blue tits on Gotl+1 种基金was also supported by‘the Ministry of Science and Higher Education’(NN304061140)‘the National Science Centre’(UMO-2012/07/D/NZ8/01317).
文摘Achromatic patches are a common element of plumage patterns in many bird species and there is growing body of evidence that in many avian taxa they can play a signaling role in mate choice.Although the blue tit Cyanistes caeruleus is a well-established model species in the studies on coloration,its white wing patch has never been examined in the context of sex-specific trait expression.In this exploratory study,we examined sexual size dimorphism and dichromatism of greater covert’s dots creating white wing patch and analyzed its correlations with current body condition and crown coloration—a trait with established role in sexual selection.Further,we qualitatively analyzed microstructural barb morphology underlying covert’s coloration.We found significant sexual dimorphism in the dot size independent of covert size and sexual dichromatism in both white dot and blue outer covert’s vane spectral characteristics.Internal structure of covert barbs within the white dot was similar to the one found in barbs from the blue part that is,with a medullary area consisting of dead keratinocytes containing channel-typeß-keratin spongy nanostructure and centrally located air cavities.However,it lacked melanosomes which was the main observed difference.Importantly,UV chroma of covert’s blue vane was positively correlated with crown UV chroma and current condition(the latter only in males),which should be a premise for further research on the signal function of the wing stripe.
基金supported by grants from the National Key Research and Development Program of China(2022YFB3806000)the National Natural Science Foundation of China(52325208 and 11974203)the Beijing Municipal Science and Technology Project(Z191100004819002).
文摘Metalenses with achromatic performance offer a new opportunity for high-quality imaging with an ultracompact configuration;however,they suffer from complex fabrication processes and low focusing efficiency.In this study,we propose an efficient design method for achromatic microlenses on a wavelength scale using materials with low dispersion,an adequately designed convex surface,and a thickness profile distribution.By taking into account the absolute chromatic aberration,relative focal length shift(FLS),and numerical aperture(NA),microlens with a certain focal length can be realized through our realized map of geometric features.Accordingly,the designed achromatic microlenses with low-dispersion fused silica were fabricated using a focused ion beam,and precise surface profiles were obtained.The fabricated microlenses exhibited a high average focusing efficiency of 65%at visible wavelengths of 410-680 nm and excellent achromatic capability via white light imaging.Moreover,the design exhibited the advantages of being polarization-insensitive and near-diffraction-limited.These results demonstrate the effectiveness of our proposed achromatic microlens design approach,which expands the prospects of miniaturized optics such as virtual and augmented reality,ultracompact microscopes,and biological endoscopy.
基金the National Natural Science Foundation of China(Grant No.61775154)the Natural Science Foundation of the Jiangsu Higher Education Institutions,China(Grant No.18KJB140015)+1 种基金the Priority Academic Program Development of Jiangsu Higher Education Institutions,Chinathe Open Research Fund of CAS Key Laboratory of Space Precision Measurement Technology,China(Grant No.SPMT2021001)。
文摘Diffractive lenses(DLs)can realize high-resolution imaging with light weight and compact size.Conventional DLs suffer large chromatic and off-axis aberrations,which significantly limits their practical applications.Although many achromatic methods have been proposed,most of them are used for designing small aperture DLs,which have low diffraction efficiencies.In the designing of diffractive achromatic lenses,increasing the aperture and improving the diffraction efficiency have become two of the most important design issues.Here,a novel phase-coded diffractive lens(PCDL)for achromatic imaging with a large aperture and high efficiency is proposed and demonstrated experimentally,and it also possesses wide field-of-view(FOV)imaging at the same time.The phase distribution of the conventional phase-type diffractive lens(DL)is coded with a cubic function to expand both the working bandwidth and the FOV of conventional DL.The proposed phase-type DL is fabricated by using the laser direct writing of grey-scale patterns for a PCDL of a diameter of 10 mm,a focal length of 100 mm,and a cubic phase coding parameter of 30π.Experimental results show that the working bandwidth and the FOV of the PCDL respectively reach 50 nm and 16°with over 8%focusing efficiency,which are in significant contrast to the counterparts of conventional DL and in good agreement with the theoretical predictions.This work provides a novel way for implementing the achromatic,wide FOV,and high-efficiency imaging with large aperture DL.
基金supported by the National Natural Science Foundation of China(32260127)the Education Department of Hainan Province(HnjgY2022-12)+1 种基金the Hainan Provincial Natural Science Foundation of China(320CXTD437)the Hainan Provincial Innovative Research Program for Graduates(Qhys2022-241)。
文摘Adaptive mate choice has been accepted as the leading theory to explain the colorful plumage of birds.This theory hypothesizes that conspicuous colors act as signals to advertise the qualities of the owners.However,a dilemma arises in that conspicuous colors may not only attract mates,but also alert predators.The"private channels of communication"hypothesis proposes that some intraspecific signals may not be visible to heterospecific animals because of different visual systems.To better understand the evolution of plumage colors and sexual selection in birds,here we studied the chromatic difference and achromatic differences of melanin-and carotenoid-based plumage coloration in five minivet species(Pericrocotus spp.)under conspecific and predator visual systems.We found that either the chromatic or achromatic difference among male or female minivets’plumage was consistently higher under conspecific vision than under predator vision for all five studied species of minivets.This result indicated that individual differences in plumage colors of minivets were visible to the conspecific receivers and hidden from potential predators as a result of evolution under predation risk and conspecific communication.However,males were under a higher risk of predation because they were more conspicuous than females to the vision of a nocturnal predator.
基金supported by the National Natural Science Foundation of China(Grant No.12004347)the Scientific and Technological Project in Henan Province(Grant Nos.222102210063 and 232102320057)+2 种基金the Aeronautical Science Foundation of China(Grant Nos.2020Z073055002 and 2019ZF055002)the Innovation and Entrepreneurship Training Program for College Students(Grant Nos.202210485007 and 202210485044)the Graduate Education Innovation Program Foundation(Grant No.2022CX53).
文摘Metasurfaces have emerged as a flexible platform for shaping the electromagnetic field via the tailoring phase,amplitude,and polarization at will.However,the chromatic aberration inherited from building blocks’diffractive nature plagues them when used in many practical applications.Current solutions for eliminating chromatic aberration usually rely on searching through many meta-atoms to seek designs that satisfy both phase and phase dispersion preconditions,inevitably leading to intensive design efforts.Moreover,most schemes are commonly valid for incidence with a specific spin state.Here,inspired by the Rayleigh criterion for spot resolution,we present a design principle for broadband achromatic and polarization-insensitive metalenses using two sets of anisotropic nanofins based on phase change material Ge2Sb2Se4Te1.By limiting the rotation angles of all nanofins to either 0 deg or 90 deg,the metalens with a suitable numerical aperture constructed by this fashion allows for achromatic and polarization-insensitive performance across the wavelength range of 4–5μm,while maintaining high focusing efficiency and diffraction-limited performance.We also demonstrate the versatility of our approach by successfully implementing the generation of broadband achromatic and polarization-insensitive focusing optical vortex.This work represents a major advance in achromatic metalenses and may find more applications in compact and chip-scale devices.
基金the National Natural Science Foundation of China(Grant No.11274188)
文摘A new achromatic phase retarder based on a metal-multilayer dielectric grating structure is designed using the rigorous coupled wave analysis method and the genetic algorithm.The optimized phase retarder can maintain phase retardation around 90°from 900 nm to 1200 nm,and the maximum deviation is less than 4.5%while the diffraction efficiencies of TE and TM waves are both higher than 95%.Numerical analysis shows the designed phase retarder has a high fabrication tolerance of groove depth,duty cycle and incident angle.This achromatic phase retarder is simple in design and stable in performance,and can be widely used in optical systems.
文摘A new doubly achromatic two-magnet beam bending system is described.Itconsists of two nonuniform dipoles separated by a small drift space.Some doublyachromatic relations are derived.The system showed excellent achromatic and focusingproperties and good quality of electron beam with small diameter.Very small diver-gence and axial symmetry were produced at the output of the system.The system isspecially suitable for low energy electron linac beam with large energy spread.
文摘A new strategy has been presented to overcome the long-term dilemma of simultaneously achieving high numerical aperture,large aperture size,and broadband achromatism of flat lenses.A stepwise phase dispersion compensation(SPDC)layer is introduced as a substrate on which the meta-atoms are positioned.
基金supported by the National Key Research and Development Program of China(No.2022YFB3602903)Guangdong University Key Laboratory for Advanced Quantum Dot Displays and Lighting(No.2017KSYS007)+2 种基金Shenzhen Key Laboratory for Advanced Quantum Dot Displays and Lighting(No.ZDSYS201707281632549)Shenzhen Science and Technology Program(No.JCYJ20220818100411025)Shenzhen Development and Reform Commission Project(Grant No.XMHT20220114005).
文摘Augmented reality(AR)displays are emerging as the next generation of interactive platform,providing deeper humandigital interactions and immersive experiences beyond traditional flat-panel displays.Diffractive waveguide is a promising optical combiner technology for AR owing to its potential for the slimmest geometry and lightest weight.However,severe chromatic aberration of diffractive coupler has constrained widespread adoption of diffractive waveguide.Wavelength-dependent light deflection,caused by dispersion in both in-coupling and out-coupling processes,results in limited full-color field of view(FOV)and nonuniform optical responses in color and angular domains.Here we introduce an innovative full-color AR system that overcomes this long-standing challenge of chromatic aberration using a combination of inverse-designed metasurface couplers and a high refractive index waveguide.The optimized metasurface couplers demonstrate true achromatic behavior across the maximum FOV supported by the waveguide(exceeding 45°).Our AR prototype based on the designed metasurface waveguide,exhibits superior color accuracy and uniformity.This unique achromatic metasurface waveguide technology is expected to advance the development of visually compelling experience in compact AR display systems.
基金supported by the National Key Research and Development Program of China(SQ2022YFB3806200)the Shaanxi Province Innovation Capability Promotion Plan(2023-CX-TD-48)+2 种基金the National Natural Science Foundation of China(62401614,62401617)the China Postdoctoral Science Foundation(2023M734275)the Postdoctoral Fellowship Program of China Postdoctoral Science Foundation(GZC20233576)。
文摘Traditionally,magic cube configurations,which have been employed to mechanically execute diverse and unconventional structural transformations,are capable of significantly boosting versatile electromagnetic responses of reconfigurable metamaterials.However,this idea is still in the initial exploration stage and faces many constraints.Here,we propose magic cube metamaterials with features of high transparency,multi-gradient phase distribution,full polarization,and high information,which manifest 47.58% optical transmittance,a 6-order phase distribution,a 77% fractional operating bandwidth,and 65.23 times information entropy of their planar counterparts.The reflection phase corresponding to coplanar lattice of the metamaterials can be dynamically and omni-directionally controlled via altering their spatial distributions through individually addressing each rotatable meta-particle while maintaining the polarization states.The optically transparent design allows for real-time visual interaction and sequence mapping of the reconfigurable metamaterials.As two proof-of-concept meta-devices,an achromatic metalens with an unchanged focal length and a switchable multi-functional beam generator is demonstrated by simulations and experiments in an ultra-wide band(8.0-18.0 GHz).This work provides an effective alternative for designing reconfigurable metamaterials with high information-entropy properties,paving a new route toward advanced equipment such as active signal processors and information encryption/decryption systems.
基金National Research Foundation(NRF)grants(RS-2024-00356928,RS-2024-00462912,RS-2024-00416272,RS-2024-00337012,RS-2024-00408286)funded by the Ministry of Science and ICT(MSIT)of the Korean government.K.W.acknowledges the NRF grant(RS-2023-00280938)funded by the MSIT of the Korean government.
文摘Since flat optics has the feature to implement a compact system,they are widely used in various applications to replace bulky refractive optics.However,they suffer from chromatic aberrations due to dispersion,limiting their effectiveness to a narrow wavelength range.Consequently,diffractive optics has been applied for dynamic beam steering within a specific wavelength region or for static steering across multiple wavelengths.This limitation has made it challenging to implement dynamic beam steering in full-color display applications.To address this issue,we developed a multi-wavelength-based optical architecture that mitigates chromatic aberrations.This system incorporates color-selective retarders,half-wave plates,polarization plates,and beam deflectors.We experimentally demonstrated an achromatic beam deflector using a dynamic phase array in transmission mode,achieving continuous tunable beam steering over multiple wavelengths at 460,520,and 638 nm.
文摘Introduction of the stepwise phase dispersion compensation layer allowed broadband achromatic metalens to have a high numerical aperture,which enabled high-resolution metalens imaging.
