The relentless pursuit of miniaturized,multifunctional photonic devices has elevated flat optics to a central position in contemporary photonics.A range of emerging trends is attracting significant research attention,...The relentless pursuit of miniaturized,multifunctional photonic devices has elevated flat optics to a central position in contemporary photonics.A range of emerging trends is attracting significant research attention,including the progression of metasurface architectures from single-layer to multilayer configurations[1-3],the broadening of functionalities from achiral to chiral responses[4,5],and the shift from linear to nonlinear operation[6,7].Particularly noteworthy is the expansion of metasurface design from local to nonlocal regimes,which plays a crucial role in shaping light with exceptional flexibility.This advancement has spurred numerous notable developments in critical application domains such as free-space compression,narrowband filtering and high-quality(high-Q)wavefront control,among others.展开更多
In this Letter, a test method based on oblique incidence is practically implemented in the interferometric measurement process. Three sets of wavefront data are achieved through cavity interference measurement with a ...In this Letter, a test method based on oblique incidence is practically implemented in the interferometric measurement process. Three sets of wavefront data are achieved through cavity interference measurement with a Fizeau interferometer and one oblique incidence measurement. An iterative algorithm is applied to retrieve the absolute surface shape of the test flat. By adding two sets of measurements, the absolute surface error of the interferometer＇s reference flat can be obtained. The new method can not only calibrate the reference flat error of interferometer, but also provide the absolute measurement method for high precision optical components applied in high power laser systems.展开更多
The physical datum method that uses the laser beam as the physical datum is proposed.A high accuracy of the straight movement on the line above 0.01 μm/100 mm is achieved through applying the method of the closed lo...The physical datum method that uses the laser beam as the physical datum is proposed.A high accuracy of the straight movement on the line above 0.01 μm/100 mm is achieved through applying the method of the closed loop feedback control that uses the laser beam as the datum.The measuring accuracy above 0.05 μm is obtained by applying the self making electric eddy displacement sensor to detect the geometric accuracy of the optical flat.It proves that the laser beam datum method can achieve the high accurcy of the straight movement and has the huge advantage.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
Planar and ultrathin liquid crystal(LC)polarization optical elements have found promising applications in augmented reality(AR),virtual reality(VR),and photonic devices.In this paper,we give a comprehensive review on ...Planar and ultrathin liquid crystal(LC)polarization optical elements have found promising applications in augmented reality(AR),virtual reality(VR),and photonic devices.In this paper,we give a comprehensive review on the operation principles,device fabrication,and performance of these optical elements.Optical simulations methods for optimizing the device performance are discussed in detail.Finally,some potential applications of these devices in AR and VR systems are illustrated and analyzed.展开更多
Two parallel optical surfaces often exhibit colorful fringes along the lines of equal thickness because of the interference of light.This simple phenomenon allows one to observe subwavelength corrugations on a reflect...Two parallel optical surfaces often exhibit colorful fringes along the lines of equal thickness because of the interference of light.This simple phenomenon allows one to observe subwavelength corrugations on a reflective surface by simply placing on it a flat reference dielectric surface,a so-called optical flat,and inspecting the resultant interference pattern.In this work,we extend this principle from dielectric surfaces to two-dimensional plasmonic nanostructures.Optical couplings between an Au nanodisk array and an Au thin film were measured quantitatively using two different techniques,namely,the classical Newton’s rings method and a closed-loop nano-positioning system.Extremely high spectral sensitivity to the inter-surface distance was observed in the near-field coupling regime,where a 1-nm change in distance could alter the resonance wavelength by almost 10 nm,440 times greater than the variation in the case without near-field coupling.With the help of a numerical fitting technique,the resonance wavelength could be determined with a precision of 0.03 nm,corresponding to a distance precision as high as 0.003 nm.Utilizing this effect,we demonstrated that a plasmonic nanodisk array can be utilized as a plasmonic optical flat,with which nanometer-deep grooves can be directly visualized using a low-cost microscope.展开更多
In this paper, a scheme for generating sinc-shaped optical Nyquist pulses based on external modulation is proposed. First, five flat optical frequency comb(OFC) lines are generated by a dual-parallel Mach–Zehnder mod...In this paper, a scheme for generating sinc-shaped optical Nyquist pulses based on external modulation is proposed. First, five flat optical frequency comb(OFC) lines are generated by a dual-parallel Mach–Zehnder modulator(DP-MZM) for optical carrier phase cancellation interference. Then, the phase-locked OFC is split into two paths, one of which is transmitted to a single-drive Mach–Zehnder modulator(SD-MZM) for the modulation of the even-order side-band suppression, and the other is used to remodulate the signal in order to obtain equally spaced comb lines. Eventually, equal frequency spaced phase-locked 15-line OFCs are generated and extremely narrow over-zero width Nyquist pulses are realized at 2.5 GHz, 5 GHz, 10 GHz and 20 GHz. The root-mean-square error(RMSE) is calculated for the generated Nyquist pulses which enables the verification of the signal quality.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
Circular polarizers based on the metasurface suffer from a trade-off between the structural complexity and thepolarization extinction ratio (ER). Herein, we present a single-layer chiral metasurface with strong circul...Circular polarizers based on the metasurface suffer from a trade-off between the structural complexity and thepolarization extinction ratio (ER). Herein, we present a single-layer chiral metasurface with strong circular dichroism. Thestructure turns a circularly polarized incident beam into a linearly polarized beam, achieving a high circular polarization ER. Theoperating wavelength of the proposed metasurface is tunable by changing the geometric parameters. The metasurface's localizedsurface plasmon resonances between structures ensure strong chiral optical effects. We further experimentally demonstrate thecircular dichroism of the fabricated metasurface.展开更多
Metasurfaces offer unprecedented flexibility in the design and control of light propagation,replacing bulk optical components and exhibiting exotic optical effects.One of the basic properties of the metasurfaces,which...Metasurfaces offer unprecedented flexibility in the design and control of light propagation,replacing bulk optical components and exhibiting exotic optical effects.One of the basic properties of the metasurfaces,which renders them as frequency selective surfaces,is the ability to transmit or reflect radiation within a narrow frequency band that can be engineered on demand.Here we introduce and demonstrate experimentally in the THz domain the concept of wavevector selective surfaces–metasurfaces transparent only within a narrow range of light propagation directions operating effectively as tunnel vision filters.Practical implementations of the new concept include applications in wavefront manipulation,observational instruments,vision and free-space communication in light-scattering environments.展开更多
Metasurfaces,also known as 2D artificial metamaterials,are attracting great attention due to their unprecedented performances and functionalities that are hard to achieve by conventional diffractive or refractive elem...Metasurfaces,also known as 2D artificial metamaterials,are attracting great attention due to their unprecedented performances and functionalities that are hard to achieve by conventional diffractive or refractive elements.With their sub-wavelength optical scatterers,metasurfaces have been utilized to freely modify different characteristics of incident light such as amplitude,polarization,phase,and frequency.Compared to traditional bulky lenses,metasurface lenses possess the advantages of flatness,light weight,and compatibility with semiconductor manufacture technology.They have been widely applied to a range of scenarios including imaging,solar energy harvesting,optoelectronic detection,etc.In this review,we will first introduce the fundamental design principles for metalens,and then report recent theoretical and experimental progress with emphasis on methods to correct chromatic and monochromatic aberrations.Finally,typical applications of metalenses and corresponding design rules will be presented,followed by a brief outlook on the prospects and challenges of this field.展开更多
Liquid crystal lenses can be achieved with either geometric phase or gradient refractive index.Which solution will ultimately prevail is open to debate.This article aims to provide a theoretical background,review the ...Liquid crystal lenses can be achieved with either geometric phase or gradient refractive index.Which solution will ultimately prevail is open to debate.This article aims to provide a theoretical background,review the latest seminal research findings,and shed light on their pros and cons from multiple perspectives.展开更多
基金supported by the STI 2030-Major Projects(2021ZD0200401)the National Natural Science Foundation of China(62222511)+1 种基金the Natural Science Foundation of Zhejiang Province(LR22F050006)the National Key Research and Development Program of China(2023YFF0613000)。
文摘The relentless pursuit of miniaturized,multifunctional photonic devices has elevated flat optics to a central position in contemporary photonics.A range of emerging trends is attracting significant research attention,including the progression of metasurface architectures from single-layer to multilayer configurations[1-3],the broadening of functionalities from achiral to chiral responses[4,5],and the shift from linear to nonlinear operation[6,7].Particularly noteworthy is the expansion of metasurface design from local to nonlocal regimes,which plays a crucial role in shaping light with exceptional flexibility.This advancement has spurred numerous notable developments in critical application domains such as free-space compression,narrowband filtering and high-quality(high-Q)wavefront control,among others.
基金supported by the National Natural Science Foundation of China(Nos.11602280 and 61705246)
文摘In this Letter, a test method based on oblique incidence is practically implemented in the interferometric measurement process. Three sets of wavefront data are achieved through cavity interference measurement with a Fizeau interferometer and one oblique incidence measurement. An iterative algorithm is applied to retrieve the absolute surface shape of the test flat. By adding two sets of measurements, the absolute surface error of the interferometer＇s reference flat can be obtained. The new method can not only calibrate the reference flat error of interferometer, but also provide the absolute measurement method for high precision optical components applied in high power laser systems.
文摘The physical datum method that uses the laser beam as the physical datum is proposed.A high accuracy of the straight movement on the line above 0.01 μm/100 mm is achieved through applying the method of the closed loop feedback control that uses the laser beam as the datum.The measuring accuracy above 0.05 μm is obtained by applying the self making electric eddy displacement sensor to detect the geometric accuracy of the optical flat.It proves that the laser beam datum method can achieve the high accurcy of the straight movement and has the huge advantage.
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Planar and ultrathin liquid crystal(LC)polarization optical elements have found promising applications in augmented reality(AR),virtual reality(VR),and photonic devices.In this paper,we give a comprehensive review on the operation principles,device fabrication,and performance of these optical elements.Optical simulations methods for optimizing the device performance are discussed in detail.Finally,some potential applications of these devices in AR and VR systems are illustrated and analyzed.
基金funding from the National Natural Science Foundation of China(Nos.11374152,11574142 and 11321063)the National Key Technologies R&D Program of China(No.2016YFA0201104)+1 种基金the National Basic Research Program of China(No.2015CB659400)the Priority Academic Program Development(PAPD)of Jiangsu Higher Education Institutions.
文摘Two parallel optical surfaces often exhibit colorful fringes along the lines of equal thickness because of the interference of light.This simple phenomenon allows one to observe subwavelength corrugations on a reflective surface by simply placing on it a flat reference dielectric surface,a so-called optical flat,and inspecting the resultant interference pattern.In this work,we extend this principle from dielectric surfaces to two-dimensional plasmonic nanostructures.Optical couplings between an Au nanodisk array and an Au thin film were measured quantitatively using two different techniques,namely,the classical Newton’s rings method and a closed-loop nano-positioning system.Extremely high spectral sensitivity to the inter-surface distance was observed in the near-field coupling regime,where a 1-nm change in distance could alter the resonance wavelength by almost 10 nm,440 times greater than the variation in the case without near-field coupling.With the help of a numerical fitting technique,the resonance wavelength could be determined with a precision of 0.03 nm,corresponding to a distance precision as high as 0.003 nm.Utilizing this effect,we demonstrated that a plasmonic nanodisk array can be utilized as a plasmonic optical flat,with which nanometer-deep grooves can be directly visualized using a low-cost microscope.
基金supported by the National Natural Science Foundation of China(No.U2241229)the Fundamental Research Funds for the Central Universities(No.CUC25QT15)。
文摘In this paper, a scheme for generating sinc-shaped optical Nyquist pulses based on external modulation is proposed. First, five flat optical frequency comb(OFC) lines are generated by a dual-parallel Mach–Zehnder modulator(DP-MZM) for optical carrier phase cancellation interference. Then, the phase-locked OFC is split into two paths, one of which is transmitted to a single-drive Mach–Zehnder modulator(SD-MZM) for the modulation of the even-order side-band suppression, and the other is used to remodulate the signal in order to obtain equally spaced comb lines. Eventually, equal frequency spaced phase-locked 15-line OFCs are generated and extremely narrow over-zero width Nyquist pulses are realized at 2.5 GHz, 5 GHz, 10 GHz and 20 GHz. The root-mean-square error(RMSE) is calculated for the generated Nyquist pulses which enables the verification of the signal quality.
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.
基金Project supported by the National Key Research and Development Program of China(No.2022YFB3206000)the Fundamental Research Funds for the Central Universities(No.2022QZJH29)+1 种基金the National Natural Science Foundation of China(Nos.92050115 and 42201336)the Zhejiang Provincial Natural Science Foundation of China(No.LZ21F050003)。
文摘Circular polarizers based on the metasurface suffer from a trade-off between the structural complexity and thepolarization extinction ratio (ER). Herein, we present a single-layer chiral metasurface with strong circular dichroism. Thestructure turns a circularly polarized incident beam into a linearly polarized beam, achieving a high circular polarization ER. Theoperating wavelength of the proposed metasurface is tunable by changing the geometric parameters. The metasurface's localizedsurface plasmon resonances between structures ensure strong chiral optical effects. We further experimentally demonstrate thecircular dichroism of the fabricated metasurface.
基金This work is supported by the UK’s Engineering and Physical Sciences Research Council through Career Acceleration Fellowship EP/G00515X/1(V.A.F.)Programme grant EP/G060363/1,by the Royal Society,and by the MOE Singapore grant MOE2011-T3-1-005
文摘Metasurfaces offer unprecedented flexibility in the design and control of light propagation,replacing bulk optical components and exhibiting exotic optical effects.One of the basic properties of the metasurfaces,which renders them as frequency selective surfaces,is the ability to transmit or reflect radiation within a narrow frequency band that can be engineered on demand.Here we introduce and demonstrate experimentally in the THz domain the concept of wavevector selective surfaces–metasurfaces transparent only within a narrow range of light propagation directions operating effectively as tunnel vision filters.Practical implementations of the new concept include applications in wavefront manipulation,observational instruments,vision and free-space communication in light-scattering environments.
基金We thank Prof.Wei Wu,Prof.Jianguo Guan,Dr.Hao Yang,and Dr.Yunxiang Wang for helpful discussions.Boxiang Song would like to acknowledge support from the National Natural Science Foundation of China(Grant No.6210031401).
文摘Metasurfaces,also known as 2D artificial metamaterials,are attracting great attention due to their unprecedented performances and functionalities that are hard to achieve by conventional diffractive or refractive elements.With their sub-wavelength optical scatterers,metasurfaces have been utilized to freely modify different characteristics of incident light such as amplitude,polarization,phase,and frequency.Compared to traditional bulky lenses,metasurface lenses possess the advantages of flatness,light weight,and compatibility with semiconductor manufacture technology.They have been widely applied to a range of scenarios including imaging,solar energy harvesting,optoelectronic detection,etc.In this review,we will first introduce the fundamental design principles for metalens,and then report recent theoretical and experimental progress with emphasis on methods to correct chromatic and monochromatic aberrations.Finally,typical applications of metalenses and corresponding design rules will be presented,followed by a brief outlook on the prospects and challenges of this field.
基金Ministry of Industry and Information Technology of China(GO0300164/001)Natural Science Foundation of Chongqing Municipality(cstb2023nscq-msx0465)+1 种基金Natural Science Foundation of Anhui Province(JZ2024AKZR0539)Guangzhou Lujia Innovation Technology(25H010102931).
文摘Liquid crystal lenses can be achieved with either geometric phase or gradient refractive index.Which solution will ultimately prevail is open to debate.This article aims to provide a theoretical background,review the latest seminal research findings,and shed light on their pros and cons from multiple perspectives.
