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
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
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
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
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
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
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
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
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
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
Flat optics have attracted interest for decades due to their flexibility in manipulating optical wave properties,which allows the miniaturization of bulky optical assemblies into integrated planar components.Recent ad...Flat optics have attracted interest for decades due to their flexibility in manipulating optical wave properties,which allows the miniaturization of bulky optical assemblies into integrated planar components.Recent advances in achromatic flat lenses have shown promising applications in various fields.However,it is a significant challenge for achromatic flat lenses with a high numerical aperture to simultaneously achieve broad bandwidth and expand the aperture sizes.Here,we present the zone division multiplex of the meta-atoms on a stepwise phase dispersion compensation(SPDC)layer to address the above challenge.In principle,the aperture size can be freely enlarged by increasing the optical thickness difference between the central and marginal zones of the SPDC layer,without the limit of the achromatic bandwidth.The SPDC layer also serves as the substrate,making the device thinner.Two achromatic flat lenses of 500 nm thickness with a bandwidth of 650–1000 nm are experimentally achieved:one with a numerical aperture of 0.9 and a radius of 20.1µm,and another with a numerical aperture of 0.7 and a radius of 30.0µm.To the best of our knowledge,they are the broadband achromatic flat lenses with highest numerical apertures,the largest aperture sizes and thinnest thickness reported so far.Microscopic imaging with a 1.10µm resolution has also been demonstrated by white light illumination,surpassing any previously reported resolution attained by achromatic metalenses and multi-level diffractive lenses.These unprecedented performances mark a substantial step toward practical applications of flat lenses.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.
In the field of long-wave infrared(LWIR) thermal imaging, vital for applications such as military surveillance and medical diagnostics, metalenses show immense potential for compact, lightweight, and low-power optical...In the field of long-wave infrared(LWIR) thermal imaging, vital for applications such as military surveillance and medical diagnostics, metalenses show immense potential for compact, lightweight, and low-power optical systems. However, to date, the development of LWIR broadband achromatic metalenses with dynamic tunable focus, which are suitable for both coaxial and off-axis applications, remains a large unexplored area. Herein, we have developed an extensive database of broadband achromatic all-As2Se3microstructure units for the LWIR range. Utilizing this database with the particle swarm optimization (PSO) algorithm, we have designed and demonstrated LWIR broadband achromatic metalenses capable of coaxial and off-axis focusing with three dynamic tunable states. This research may have potential applications for the design of compact, high-performance optical devices, including those with extreme depth-of-field and wide-angle imaging capabilities.展开更多
Achromatic focusing is essential for broadband operation, which has recently been realised from visible to infrared wavelengths using a metasurface. Similarly, multi-terahertz functional devices can be encoded in a de...Achromatic focusing is essential for broadband operation, which has recently been realised from visible to infrared wavelengths using a metasurface. Similarly, multi-terahertz functional devices can be encoded in a desired metasurface phase profile. However, metalenses suffer from larger chromatic aberrations because of the intrinsic dispersion of each unit element. Here, we propose an achromatic metalens with C-shaped unit elements working from 0.3 to 0.8 THz with a bandwidth of approximately 91% over the centre frequency. The designed metalens possesses a high working efficiency of more than 68% at the peak and a relatively high numerical aperture of 0.385. We further demonstrate the robustness of our Cshaped metalens, considering lateral shape deformations and deviations in the etching depth. Our metalens design opens an avenue for future applications of terahertz meta-devices in spectroscopy, time-offlight tomography and hyperspectral imaging systems.展开更多
Lenses are crucial to light-enabled technologies.Conventional lenses have been perfected to achieve near-diffraction-limited resolution and minimal chromatic aberrations.However,such lenses are bulky and cannot focus ...Lenses are crucial to light-enabled technologies.Conventional lenses have been perfected to achieve near-diffraction-limited resolution and minimal chromatic aberrations.However,such lenses are bulky and cannot focus light into a hotspot smaller than a half-wavelength of light.Pupil filters,initially suggested by Toraldo di Francia,can overcome the resolution constraints of conventional lenses but are not intrinsically chromatically corrected.Here we report single-element planar lenses that not only deliver sub-wavelength focusing,thus beating the diffraction limit of conventional refractive lenses,but also focus light of different colors into the same hotspot.Using the principle of super-oscillations,we designed and fabricated a range of binary dielectric and metallic lenses for visible and infrared parts of the spectrum that are manufactured on silicon wafers,silica substrates and optical fiber tips.Such low-cost,compact lenses could be useful in mobile devices,data storage,surveillance,robotics,space applications,imaging,manufacturing with light and spatially resolved nonlinear microscopies.展开更多
Metalenses are expected to play an increasingly important role in miniaturized and integrated optical imaging components/systems.However,devising broadband achromatic metalenses with high focusing efficiencies is stil...Metalenses are expected to play an increasingly important role in miniaturized and integrated optical imaging components/systems.However,devising broadband achromatic metalenses with high focusing efficiencies is still quite challenging.In this work,we proposed an aperture-shared partition phase cooperative manipulation approach for designing a highefficiency broadband achromatic metalens composed of two concentric sub-metalenses.As a proof-of-concept,an achromatic polarization-independent metalens is successfully designed for the visible and near-infrared range from450 nm to 1400 nm with the focusing efficiency over 70% for the wavelength range of 600 nm to 1400 nm.The approach reported here provides a possibility for designing a high-performance metalens,which has great potential applications in integrated optics.展开更多
Metalens are planar lenses composed of the subwavelengthh arrays,which have unconventional and versatile functionalities to manipulate the light fields compared with the traditional lens.It is noted that the most meta...Metalens are planar lenses composed of the subwavelengthh arrays,which have unconventional and versatile functionalities to manipulate the light fields compared with the traditional lens.It is noted that the most metalens are designed in a monochromatic mode in the visible or mid-infrared range(mid-IR),however,the broadband range is needed in many practical applications,such as spectroscopy,sensing,and imaging.Here,we design and demonstrate a broadband achromatic dielectric metalens in the mid-IR range of 4μm-5μm for near diffraction-limited(1.0a)focusing.The broadband achromatic propagation and focusing of the metalens are designed and simulated by constructing and optimizing the phase profile.The Pancharatnam-Berry(P-B)phases of all the elements contribute to the main phase increment of the whole phase profile of the metalens.The additional phase is constructed and optimized by using the random search algorithm to obtain the optimized size of all the elements.The focusing efficiency of the achromatic metalens is also optimized and averaged as the result of phase optimization within a wide band for the building elements,while it is lowered comparing with the regular metalens without broadband achromatic designing.Using this combined designing approach,various flat achromatic devices with the broadband metalens can find a new way for full-color detection and imaging.展开更多
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 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.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.
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.
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 R&D Program of China(No.2021YFA1400800)National Natural Science Foundation of China(Nos.12374363,12074444,and 11704421)+2 种基金Guangdong Basic and Applied Basic Research Foundation(No.2020B0301030009)Guangdong Provincial Natural Science Fund Projects(2024B1515040013)Guangdong Provincial Quantum Science Strategic Initiative(GDZX2306002,GDZX2206001)。
文摘Flat optics have attracted interest for decades due to their flexibility in manipulating optical wave properties,which allows the miniaturization of bulky optical assemblies into integrated planar components.Recent advances in achromatic flat lenses have shown promising applications in various fields.However,it is a significant challenge for achromatic flat lenses with a high numerical aperture to simultaneously achieve broad bandwidth and expand the aperture sizes.Here,we present the zone division multiplex of the meta-atoms on a stepwise phase dispersion compensation(SPDC)layer to address the above challenge.In principle,the aperture size can be freely enlarged by increasing the optical thickness difference between the central and marginal zones of the SPDC layer,without the limit of the achromatic bandwidth.The SPDC layer also serves as the substrate,making the device thinner.Two achromatic flat lenses of 500 nm thickness with a bandwidth of 650–1000 nm are experimentally achieved:one with a numerical aperture of 0.9 and a radius of 20.1µm,and another with a numerical aperture of 0.7 and a radius of 30.0µm.To the best of our knowledge,they are the broadband achromatic flat lenses with highest numerical apertures,the largest aperture sizes and thinnest thickness reported so far.Microscopic imaging with a 1.10µm resolution has also been demonstrated by white light illumination,surpassing any previously reported resolution attained by achromatic metalenses and multi-level diffractive lenses.These unprecedented performances mark a substantial step toward practical applications of flat lenses.
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.
基金supported by the National Natural Science Foundation of China (No.62105171)Zhejiang Provincial Natural Science Foundation (No.LY24F050001)+2 种基金Joint Funds of the National Natural Science Foundation of China (No.U21A2056)Key Research and Development Program of Zhejiang Province (No.2021C01025)K.C.Wong Magna Fund in Ningbo University。
文摘In the field of long-wave infrared(LWIR) thermal imaging, vital for applications such as military surveillance and medical diagnostics, metalenses show immense potential for compact, lightweight, and low-power optical systems. However, to date, the development of LWIR broadband achromatic metalenses with dynamic tunable focus, which are suitable for both coaxial and off-axis applications, remains a large unexplored area. Herein, we have developed an extensive database of broadband achromatic all-As2Se3microstructure units for the LWIR range. Utilizing this database with the particle swarm optimization (PSO) algorithm, we have designed and demonstrated LWIR broadband achromatic metalenses capable of coaxial and off-axis focusing with three dynamic tunable states. This research may have potential applications for the design of compact, high-performance optical devices, including those with extreme depth-of-field and wide-angle imaging capabilities.
基金supported in part by the National Natural Science Foundation of China(11874266,11604208,61705131,and 81701745)Shanghai Science and Technology Committee of China(16ZR1445600 and 16ZR1445500)+2 种基金Chen Guang Program of China(17CG49)S.W.and T.L.thank the support from National Key R&D Program of China(2017YFA0303700,2016YFA0202103)the National Natural Science Foundation of China(11822406,11834007,11674167,11621091,11774164,and 91850204)
文摘Achromatic focusing is essential for broadband operation, which has recently been realised from visible to infrared wavelengths using a metasurface. Similarly, multi-terahertz functional devices can be encoded in a desired metasurface phase profile. However, metalenses suffer from larger chromatic aberrations because of the intrinsic dispersion of each unit element. Here, we propose an achromatic metalens with C-shaped unit elements working from 0.3 to 0.8 THz with a bandwidth of approximately 91% over the centre frequency. The designed metalens possesses a high working efficiency of more than 68% at the peak and a relatively high numerical aperture of 0.385. We further demonstrate the robustness of our Cshaped metalens, considering lateral shape deformations and deviations in the etching depth. Our metalens design opens an avenue for future applications of terahertz meta-devices in spectroscopy, time-offlight tomography and hyperspectral imaging systems.
基金supported by the Agency for Science,Technology and Research(A*STAR)of Singapore(Grants 122-360-0009)the Singapore Ministry of Education(Grant MOE2011-T3-1-005)+1 种基金the Engineering and Physical Sciences Research Council UK(Grants EP/F040644/1 and EP/M009122/1)the University of Southampton Enterprise Fund.
文摘Lenses are crucial to light-enabled technologies.Conventional lenses have been perfected to achieve near-diffraction-limited resolution and minimal chromatic aberrations.However,such lenses are bulky and cannot focus light into a hotspot smaller than a half-wavelength of light.Pupil filters,initially suggested by Toraldo di Francia,can overcome the resolution constraints of conventional lenses but are not intrinsically chromatically corrected.Here we report single-element planar lenses that not only deliver sub-wavelength focusing,thus beating the diffraction limit of conventional refractive lenses,but also focus light of different colors into the same hotspot.Using the principle of super-oscillations,we designed and fabricated a range of binary dielectric and metallic lenses for visible and infrared parts of the spectrum that are manufactured on silicon wafers,silica substrates and optical fiber tips.Such low-cost,compact lenses could be useful in mobile devices,data storage,surveillance,robotics,space applications,imaging,manufacturing with light and spatially resolved nonlinear microscopies.
基金supported by the National Natural Science Foundation of China (Nos. 61875042, 11627803, DMR-61804010, and 11204209)Youth Innovation Promotion Association CAS (No. Y201911)+1 种基金Scientific Instrument Developing Project CAS (No. Y8512911)Natural Science Foundation of Tianjin (No. 17JCYBJC16200)
文摘Metalenses are expected to play an increasingly important role in miniaturized and integrated optical imaging components/systems.However,devising broadband achromatic metalenses with high focusing efficiencies is still quite challenging.In this work,we proposed an aperture-shared partition phase cooperative manipulation approach for designing a highefficiency broadband achromatic metalens composed of two concentric sub-metalenses.As a proof-of-concept,an achromatic polarization-independent metalens is successfully designed for the visible and near-infrared range from450 nm to 1400 nm with the focusing efficiency over 70% for the wavelength range of 600 nm to 1400 nm.The approach reported here provides a possibility for designing a high-performance metalens,which has great potential applications in integrated optics.
基金supported by the Key Research&Development Project of Sichuan Provincial Department of Science and Technology(Grant No.2021YFG0369)State Grid Science and Technology Project(Grant No.55700-202127198A-0-0-00).
文摘Metalens are planar lenses composed of the subwavelengthh arrays,which have unconventional and versatile functionalities to manipulate the light fields compared with the traditional lens.It is noted that the most metalens are designed in a monochromatic mode in the visible or mid-infrared range(mid-IR),however,the broadband range is needed in many practical applications,such as spectroscopy,sensing,and imaging.Here,we design and demonstrate a broadband achromatic dielectric metalens in the mid-IR range of 4μm-5μm for near diffraction-limited(1.0a)focusing.The broadband achromatic propagation and focusing of the metalens are designed and simulated by constructing and optimizing the phase profile.The Pancharatnam-Berry(P-B)phases of all the elements contribute to the main phase increment of the whole phase profile of the metalens.The additional phase is constructed and optimized by using the random search algorithm to obtain the optimized size of all the elements.The focusing efficiency of the achromatic metalens is also optimized and averaged as the result of phase optimization within a wide band for the building elements,while it is lowered comparing with the regular metalens without broadband achromatic designing.Using this combined designing approach,various flat achromatic devices with the broadband metalens can find a new way for full-color detection and imaging.
