We developed an imaging technique combining two-photon computed super-resolution microscopy and suction-based stabilization to achieve the resolution of the single-cell level and organelles in vivo.To accomplish this,...We developed an imaging technique combining two-photon computed super-resolution microscopy and suction-based stabilization to achieve the resolution of the single-cell level and organelles in vivo.To accomplish this,a conventional two-photon microscope was equipped with a 3D-printed holders,which stabilize the tissue surface within the focal plane of immersion objectives.Further computational image stabilization and noise reduction were applied,followed by superresolution radial fluctuations(SRRF)analysis,doubling image resolution,and enhancing signal-to-noise ratios for in vivo subcellular process investigation.Stabilization of<1μm was obtained by suction,and<25 nm were achieved by subsequent algorithmic image stabilization.A Mito-Dendra2 mouse model,expressing green fluorescent protein(GFP)in mitochondria,demonstrated the potential of long-term intravital subcellular imaging.In vivo mitochondrial fission and fusion,mitochondrial status migration,and the effects of alcohol consumption(modeled as an alcoholic liver disease)and berberine treatment on hepatocyte mitochondrial dynamics are directly observed intravitally.Suction-based stabilization in two-photon intravital imaging,coupled with computational super-resolution holds promise for advancing in vivo subcellular imaging studies.展开更多
Ti33O55 films are deposited with the help of an electron beam evaporator for their applications in metasurfaces. The film of subwavelength （632nm） thickness is deposited on a silicon substrate and annealed at 400℃....Ti33O55 films are deposited with the help of an electron beam evaporator for their applications in metasurfaces. The film of subwavelength （632nm） thickness is deposited on a silicon substrate and annealed at 400℃. The ellipsometry result shows a high refractive index above 2.5 with the minimum absorption coefficient in the visible region, which is necessary for high efficiency of transparent metasurfaces. Atomic force microscopy analysis is employed to measure the roughness of the as-deposited films. It is seen from micrographs that the deposited films are very smooth with the minimum roughness to prevent scattering and absorption losses for metasurface devices. The absence of grains and cracks can be seen by scanning electron microscope analysis, which is favorable for electron beam lithography. Fourier transform infrared spectroscopy reveals the transmission and reflection obtained from the film deposited on glass substrates. The as-deposited film shows high transmission above 60%, which is in good agreement with metasurfaces.展开更多
Waveguide-integrated mid-infrared(MIR)photodetectors are pivotal components for the development of molecular spectroscopy applications,leveraging mature photonic integrated circuit(PIC)technologies.Despite various str...Waveguide-integrated mid-infrared(MIR)photodetectors are pivotal components for the development of molecular spectroscopy applications,leveraging mature photonic integrated circuit(PIC)technologies.Despite various strategies,critical challenges still remain in achieving broadband photoresponse,cooling-free operation,and large-scale complementary-metal-oxide-semiconductor(CMOS)-compatible manufacturability.To leap beyond these limitations,the bolometric effect–a thermal detection mechanism–is introduced into the waveguide platform.More importantly,we pursue a free-carrier absorption(FCA)process in germanium(Ge)to create an efficient light-absorbing medium,providing a pragmatic solution for full coverage of the MIR spectrum without incorporating exotic materials into CMOS.Here,we present an uncooled waveguide-integrated photodetector based on a Ge-on-insulator(Ge-OI)PIC architecture,which exploits the bolometric effect combined with FCA.Notably,our device exhibits a broadband responsivity of 28.35%/mW across 4030–4360 nm(and potentially beyond),challenging the state of the art,while achieving a noise-equivalent power of 4.03×10^(−7) W/Hz^(0.5) at 4180 nm.We further demonstrate label-free sensing of gaseous carbon dioxide(CO_(2))using our integrated photodetector and sensing waveguide on a single chip.This approach to room-temperature waveguide-integrated MIR photodetection,harnessing bolometry with FCA in Ge,not only facilitates the realization of fully integrated lab-on-a-chip systems with wavelength flexibility but also provides a blueprint for MIR PICs with CMOS-foundry-compatibility.展开更多
Dramatic fluorescence enhancement in two-dimensional(2D)van der Waals materials(vdWMs)coupled to plasmonic nanostructures has the potential to enable ultrathin,flexible,and high-brightness illumination devices.However...Dramatic fluorescence enhancement in two-dimensional(2D)van der Waals materials(vdWMs)coupled to plasmonic nanostructures has the potential to enable ultrathin,flexible,and high-brightness illumination devices.However,addressing the limitation of locally scattered small plasmon-enhanced areas remains challenging.Here,we present a 2D plasmonic enhancement of photoluminescence(PL)spanning nearly 800μm^(2),enabled by surface lattice resonance(SLR)in a 2D vdWM-Au slot lattice hybrid.The Au slot lattice is designed and fabricated using Babinet’s principle and Rayleigh’s anomaly to maximize radiative decay rate and induce non-local photo-excitation in a MoSe_(2)monolayer.For emitted PL coupled with SLR,enhanced by up to 32-fold,we investigate its in-plane directivity and long-range propagation using angle-and space-resolved spectroscopic PL measurements.Our experiment reveals that a nearly 800μm^(2)2D luminescent sheet can be achieved regardless of the size of the MoSe_(2)crystal,even with a sub-μm^(2)flake.This work provides a new type of ultrabright,large-area 2D luminescent material,suitable for a range of optical illumination,communication,and sensing devices.展开更多
Extending the depth of field(DOF)is essential for large-volume imaging in biological research,particularly in thick tissue environments.Bessel beams and their variants are widely used due to their simplicity and have ...Extending the depth of field(DOF)is essential for large-volume imaging in biological research,particularly in thick tissue environments.Bessel beams and their variants are widely used due to their simplicity and have been successfully applied to in vivo imaging.A recent advancement demonstrated the application of droplet Bessel beams(DBBs)for multi-photon microscopy,enabling functional imaging in live mouse brains.However,DBB generation inevitably requires active phase switching devices such as spatial light modulators,which reduce imaging speed and increase system complexity.This study introduces a droplet Bessel beam metalens(DBBM)that passively generates DBBs without phase switching by employing rectangular meta-atoms for orthogonal polarization modulation and X-shaped meta-atoms for amplitude control.Optical simulations identify optimal DBBM parameters that maximize the point spread function(PSF)aspect ratio while minimizing energy leakage into side lobes.Furthermore,the fabricated DBBM produces PSFs consistent with simulations.Imaging simulations based on three-dimensional confocal images of expansion microscopy-treated organoids demonstrated that the DBBM maintains superior performance even in the presence of aberrations.These findings establish the DBBM as a compact and passive solution for extended DOF imaging without the need for beam-shaping devices.Metalens technology is anticipated to have broad applications in real-time volumetric bioimaging and enable simplified optical system designs.展开更多
Image scanning microscopy(ISM)is a promising imaging technique that offers sub-diffraction-limited resolution and optical sectioning.Theoretically,ISM can improve the optical resolution by a factor of two through pixe...Image scanning microscopy(ISM)is a promising imaging technique that offers sub-diffraction-limited resolution and optical sectioning.Theoretically,ISM can improve the optical resolution by a factor of two through pixel reassignment and deconvolution.Multifocal array illumination and scanning have been widely adopted to implement ISM because of their simplicity.Conventionally,digital micromirror devices(DMDs)1 and microlens arrays(MLAs)2,3 have been used to generate dense and uniform multifocal arrays for ISM,which are critical for achieving fast imaging and high-quality ISM reconstruction.However,these approaches have limitations in terms of cost,numerical aperture(NA),pitch,and uniformity,making it challenging to create dense and high-quality multifocal arrays at high NA.To overcome these limitations,we introduced a novel multifocal metalens design strategy called the hybrid multiplexing method,which combines two conventional multiplexing approaches:phase addition and random multiplexing.Through numerical simulations,we demonstrate that the proposed method generates more uniform and denser multifocal arrays than conventional methods,even at small pitches.As a proof of concept,we fabricated a multifocal metalens generating 40×40 array of foci with a 3μm pitch and NA of 0.7 operating at a wavelength of 488 nm and then constructed the multifocal metalens-based ISM(MMISM).We demonstrated that MMISM successfully resolved sub-diffraction-limited features in imaging of microbead samples and forebrain organoid sections.The results showed that MMISM imaging achieved twice the diffraction-limited resolution and revealed clearer structural features of neurons compared to wide-field images.We anticipate that our novel design strategy can be widely applied to produce multifunctional optical elements and replace conventional optical elements in specialized applications.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.
Taking inspiration from beautiful colors in nature,structural colors produced from nanostructured metasurfaces have shown great promise as a platform for bright,highly saturated,and high-resolution colors.Both plasmon...Taking inspiration from beautiful colors in nature,structural colors produced from nanostructured metasurfaces have shown great promise as a platform for bright,highly saturated,and high-resolution colors.Both plasmonic and dielectric materials have been employed to produce static colors that fulfil the required criteria for high-performance color printing,however,for practical applications in dynamic situations,a form of tunability is desirable.Combinations of the additive color palette of red,green,and blue enable the expression of further colors beyond the three primary colors,while the simultaneous intensity modulation allows access to the full color gamut.Here,we demonstrate an electrically tunable metasurface that can represent saturated red,green,and blue pixels that can be dynamically and continuously controlled between on and off states using liquid crystals.We use this to experimentally realize ultrahigh-resolution color printing,active multicolor cryptographic applications,and tunable pixels toward high-performance full-color reflective displays.展开更多
Metasurfaces consisting of subwavelength structures,so-called meta-atoms,have steadily attracted considerable attention for advanced holography due to their advantages in terms of high-resolution holographic images,la...Metasurfaces consisting of subwavelength structures,so-called meta-atoms,have steadily attracted considerable attention for advanced holography due to their advantages in terms of high-resolution holographic images,large field of view,and compact device volume.In contrast to conventional holographic displays using bulky conventional diffractive optical elements,metasurface holography enables arbitrary complex wavefront shaping with a much smaller footprint.In this review,we classify metasurface holography according to the meta-atom design methodologies,which can further expand hologram functionalities.We describe light-matter interactions,particularly in metasurface systems,using the relevant the Jones matrix to rigorously explain modulations of the amplitude,phase,and polarization of light.Six different types of metaatoms are presented,and the corresponding achievable wavefronts that form the holographic images in the far-field are also provided.Such a simple classification will give a straightforward approach to design and further realize advanced metasurface holographic devices.展开更多
With the rapid progress in computer science,including artificial intelligence,big data and cloud computing,full-space spot generation can be pivotal to many practical applications,such as facial recognition,motion det...With the rapid progress in computer science,including artificial intelligence,big data and cloud computing,full-space spot generation can be pivotal to many practical applications,such as facial recognition,motion detection,augmented reality,etc.These opportunities may be achieved by using diffractive optical elements(DOEs)or light detection and ranging(LIDAR).However,DOEs suffer from intrinsic limitations,such as demanding depth-controlled fabrication techniques,large thicknesses(more than the wavelength),Lambertian operation only in half space,etc.LIDAR nevertheless relies on complex and bulky scanning systems,which hinders the miniaturization of the spot generator.Here,inspired by a Lambertian scatterer,we report a Hermitian-conjugate metasurface scrambling the incident light to a cloud of random points in full space with compressed information density,functioning in both transmission and reflection spaces.Over 4044 random spots are experimentally observed in the entire space,covering angles at nearly 90°.Our scrambling metasurface is made of amorphous silicon with a uniform subwavelength height,a nearly continuous phase coverage,a lightweight,flexible design,and low-heat dissipation.Thus,it may be mass produced by and integrated into existing semiconductor foundry designs.Our work opens important directions for emerging 3D recognition sensors,such as motion sensing,facial recognition,and other applications.展开更多
Helicity-multiplexed metasurfaces based on symmetric spin–orbit interactions (SOIs) have practical limits because they cannot provide central-symmetric holographic imaging. Asymmetric SOIs can effectively address suc...Helicity-multiplexed metasurfaces based on symmetric spin–orbit interactions (SOIs) have practical limits because they cannot provide central-symmetric holographic imaging. Asymmetric SOIs can effectively address such limitations, with several exciting applications in various fields ranging from asymmetric data inscription in communications to dual side displays in smart mobile devices. Low-loss dielectric materials provide an excellent platform for realizing such exotic phenomena efficiently. In this paper, we demonstrate an asymmetric SOI-dependent transmission-type metasurface in the visible domain using hydrogenated amorphous silicon (a-Si:H) nanoresonators. The proposed design approach is equipped with an additional degree of freedom in designing bi-directional helicity-multiplexed metasurfaces by breaking the conventional limit imposed by the symmetric SOI in half employment of metasurfaces for one circular handedness. Two on-axis, distinct wavefronts are produced with high transmission efficiencies, demonstrating the concept of asymmetric wavefront generation in two antiparallel directions. Additionally, the CMOS compatibility of a-Si:H makes it a cost-effective alternative to gallium nitride (GaN) and titanium dioxide (TiO2) for visible light. The cost-effective fabrication and simplicity of the proposed design technique provide an excellent candidate for high-efficiency, multifunctional, and chip-integrated demonstration of various phenomena.展开更多
Structural coloration techniques have improved display science due to their high durability in terms of resistance to bleaching and abrasion,and low energy consumption.Here,we propose and demonstrate an all-solid-stat...Structural coloration techniques have improved display science due to their high durability in terms of resistance to bleaching and abrasion,and low energy consumption.Here,we propose and demonstrate an all-solid-state,large-area,lithography-free color filter that can switch structural color based on a doped semiconductor.Particularly,an indium-gallium-zinc-oxide(IGZO)thin film is used as a passive index-changing layer.The refractive index of the IGZO layer is tuned by controlling the charge carrier concentration;a hydrogen plasma treatment is used to control the conductivity of the IGZO layer.In this paper,we verify the color modulation using finite difference time domain simulations and experiments.The IGZO-based color filter technology proposed in this study will pave the way for charge-controlled tunable color filters displaying a wide gamut of colors on demand.展开更多
Chiro-optical effects offer a wide range of potential applications in nanophotonics,such as advanced imaging and molecular sensing and separation.Flat single-layer metasurfaces composed of subwavelength meta-atoms hav...Chiro-optical effects offer a wide range of potential applications in nanophotonics,such as advanced imaging and molecular sensing and separation.Flat single-layer metasurfaces composed of subwavelength meta-atoms have gained significant attention due to their exceptional characteristics in light–matter interactions.Although metasurface-based devices have manipulated electromagnetic waves,the compact on-chip realization of giant chiro-optical effects remains a challenge at optical frequencies.In this work,we experimentally and numerically demonstrate an all-dielectric metasurface to realize large chiro-optical effects in the visible regime.Notably,the proposed strategy of utilizing achiral nanofins instead of conventional chiral structures provides an extra degree of design freedom.The mutual coupling between carefully engineered nanofins produces constructive and destructive interference,leading to the asymmetric transmission of 70%and average circular dichroism exceeding 60%.We investigate the underlying mechanism behind the chiro-optical effects using the theory of multipolar decomposition.The proposed design mechanism maximizes the chiro-optical response through a single-layer metasurface with potential applications in high-efficiency integrated ultrathin polarization rotators and shapers,chiral polarizers for optical displays,chiral beam splitters,and chiral sensors.展开更多
The capillary force effect is one of the most important fabrication parameters that must be considered at the micro/nanoscale because it is strong enough to deform micro/nanostructures.However,the deformation of micro...The capillary force effect is one of the most important fabrication parameters that must be considered at the micro/nanoscale because it is strong enough to deform micro/nanostructures.However,the deformation of micro/nanostructures due to such capillary forces(e.g.,stiction and collapse)has been regarded as an undesirable and uncontrollable obstacle to be avoided during fabrication.Here,we present a capillary-force-induced collapse lithography(CCL)technique,which exploits the capillary force to precisely control the collapse of micro/nanostructures.CCL uses electron-beam lithography,so nanopillars with various shapes can be fabricated by precisely controlling the capillary-force-dominant cohesion process and the nanopillar-geometry-dominant collapse process by adjusting the fabrication parameters such as the development time,electron dose,and shape of the nanopillars.CCL aims to achieve sub-10-nm plasmonic nanogap structures that promote extremely strong focusing of light.CCL is a simple and straightforward method to realize such nanogap structures that are needed for further research such as on plasmonic nanosensors.展开更多
We experimentally demonstrate an all-pass microring resonator (MRR) based on a Y_(2)O_(3)BOX germanium-oninsulator (GeOI) platform operating in the mid-IR region.The ring resonator was numerically designed to have a h...We experimentally demonstrate an all-pass microring resonator (MRR) based on a Y_(2)O_(3)BOX germanium-oninsulator (GeOI) platform operating in the mid-IR region.The ring resonator was numerically designed to have a high quality (Q) factor in the 4.18μm to 4.22μm wavelength range in the fundamental TE mode.According to our design,the GeOI ring resonator was fabricated by the direct wafer-bonding technology with an yttria(Y_(2)O_(3)) buried oxide layer,which is transparent at the mid-IR region,for the bonding interface and the electron beam lithography.The experimental resonant characteristic was obtained using our fiber-based mid-IR measurement setup.The GeOI single MRR exhibited an extinction ratio (ER) of 15.28 dB and an insertion loss (IL)of 1.204 dB,and the racetrack showed an ER of 22.77 dB and an IL of 0.627 dB.Furthermore,the free spectral range of the device was 5.29 nm,and the loaded Q factor of 94,528 (176,158 of intrinsic Q factor) was extracted by the nonlinear least squares method.We believe this demonstration of our GeOI MRR offers a valuable opportunity to implement multipurpose devices such as optical sensors,switches,and filters in the mid-IR range.展开更多
Advanced imaging techniques have been widely used in various biological studies.Currently,numerous imaging modalities are utilized in biological applications,including medical imaging,diagnosis,biometrics,and fundamen...Advanced imaging techniques have been widely used in various biological studies.Currently,numerous imaging modalities are utilized in biological applications,including medical imaging,diagnosis,biometrics,and fundamental biological research.Consequently,the demand for faster,clearer,and more accurate imaging techniques to support sophisticated biological studies has increased.However,there is a limitation in enhancing performance of imaging devices owing to the system complexity associated with bulky conventional optical elements.To address this issue,metasurfaces,which are flat and compact optical elements,have been considered potential candidates for biological imaging.Here,we comprehensively discuss the metasurface empowered various imaging applications in biology,including their working principles and design strategies.Furthermore,we compared conventional imaging modalities with the metasurface-based imaging system.Finally,we discuss the current challenges and offer future perspectives on metasurfaces.展开更多
Infrared chiral plasmonic metamaterials based on perpendicularly positioned nanorods enable surface-enhanced vibrational circular dichroism for more selective and sensitive identification of protein fingerprints and e...Infrared chiral plasmonic metamaterials based on perpendicularly positioned nanorods enable surface-enhanced vibrational circular dichroism for more selective and sensitive identification of protein fingerprints and enantioselective sensing,which creates a new pathway for chemical or biomedical applications.展开更多
基金supported by the Ministry of Science,ICT and Future Planning(MSIP)through the National Research Foundation of Korea(NRF)(RS-2024-00450201)supported by a grant from the Korea Health Technology R&D Project through the Korea Health Industry Development Institute(KHIDI),funded by the Ministry of Health and Welfare,Republic of Korea(HI22C1374).
文摘We developed an imaging technique combining two-photon computed super-resolution microscopy and suction-based stabilization to achieve the resolution of the single-cell level and organelles in vivo.To accomplish this,a conventional two-photon microscope was equipped with a 3D-printed holders,which stabilize the tissue surface within the focal plane of immersion objectives.Further computational image stabilization and noise reduction were applied,followed by superresolution radial fluctuations(SRRF)analysis,doubling image resolution,and enhancing signal-to-noise ratios for in vivo subcellular process investigation.Stabilization of<1μm was obtained by suction,and<25 nm were achieved by subsequent algorithmic image stabilization.A Mito-Dendra2 mouse model,expressing green fluorescent protein(GFP)in mitochondria,demonstrated the potential of long-term intravital subcellular imaging.In vivo mitochondrial fission and fusion,mitochondrial status migration,and the effects of alcohol consumption(modeled as an alcoholic liver disease)and berberine treatment on hepatocyte mitochondrial dynamics are directly observed intravitally.Suction-based stabilization in two-photon intravital imaging,coupled with computational super-resolution holds promise for advancing in vivo subcellular imaging studies.
基金Information Technology University of the Punjab, Lahore, Pakistan for financial supportthe financial support by Engineering Research Center Program(NRF-2015R1A5A1037668)+1 种基金global Ph.D. fellowship(NRF-2016H1A2A1906519)the KRF fellowship(NRF-2017H1D3A1A02011379)through the National Research Foundation of Korea (NRF) funded by the Ministry of Science, ICT and Future Planning (MSIP) of Korean government
文摘Ti33O55 films are deposited with the help of an electron beam evaporator for their applications in metasurfaces. The film of subwavelength （632nm） thickness is deposited on a silicon substrate and annealed at 400℃. The ellipsometry result shows a high refractive index above 2.5 with the minimum absorption coefficient in the visible region, which is necessary for high efficiency of transparent metasurfaces. Atomic force microscopy analysis is employed to measure the roughness of the as-deposited films. It is seen from micrographs that the deposited films are very smooth with the minimum roughness to prevent scattering and absorption losses for metasurface devices. The absence of grains and cracks can be seen by scanning electron microscope analysis, which is favorable for electron beam lithography. Fourier transform infrared spectroscopy reveals the transmission and reflection obtained from the film deposited on glass substrates. The as-deposited film shows high transmission above 60%, which is in good agreement with metasurfaces.
基金supported by the National Research Foundation of Korea(NRF)(2023R1A2C2002777,RS-2024-00407767)the KIST Institutional Program(2E33052)the BK21 FOUR.
文摘Waveguide-integrated mid-infrared(MIR)photodetectors are pivotal components for the development of molecular spectroscopy applications,leveraging mature photonic integrated circuit(PIC)technologies.Despite various strategies,critical challenges still remain in achieving broadband photoresponse,cooling-free operation,and large-scale complementary-metal-oxide-semiconductor(CMOS)-compatible manufacturability.To leap beyond these limitations,the bolometric effect–a thermal detection mechanism–is introduced into the waveguide platform.More importantly,we pursue a free-carrier absorption(FCA)process in germanium(Ge)to create an efficient light-absorbing medium,providing a pragmatic solution for full coverage of the MIR spectrum without incorporating exotic materials into CMOS.Here,we present an uncooled waveguide-integrated photodetector based on a Ge-on-insulator(Ge-OI)PIC architecture,which exploits the bolometric effect combined with FCA.Notably,our device exhibits a broadband responsivity of 28.35%/mW across 4030–4360 nm(and potentially beyond),challenging the state of the art,while achieving a noise-equivalent power of 4.03×10^(−7) W/Hz^(0.5) at 4180 nm.We further demonstrate label-free sensing of gaseous carbon dioxide(CO_(2))using our integrated photodetector and sensing waveguide on a single chip.This approach to room-temperature waveguide-integrated MIR photodetection,harnessing bolometry with FCA in Ge,not only facilitates the realization of fully integrated lab-on-a-chip systems with wavelength flexibility but also provides a blueprint for MIR PICs with CMOS-foundry-compatibility.
基金supported by the National Research Foundation of Korea(NRF)grants(RS-2023-00283500,RS-2025-00559639,RS-2024-00412690,RS-2023-00254055)the Samsung Science and Technology Foundation(SSTP-BA2102-05)+6 种基金the MSIT(Ministry of Science and ICT)under the ITRC(Information Technology Research Center)support program(IITP-2022-RS-2022-00164799)J.R.acknowledges the POSCO-POSTECH-RIST Convergence Research Center program funded by POSCO,and the National Research Foundation(NRF)grant(RS-2024-00356928)funded by the Ministry of Science and ICT(MSIT)of the Korean government.D.K.O.acknowledges the Hyundai Motor Chung Mong-Koo fellowshipJ.M.acknowledges the Presidential Sejong fellowship(RS-2023-00252778)funded by the MSIT of the Korean governmentY.Kim acknowledges the Hyundai Motor Chung Mong-Koo fellowship and the NRF PhD fellowship(NRF-2022R1A6A3A13066251)funded by the Ministry of Education(MOE)of the Korean government.T.K.and J.K.acknowledge the support from the Institute of Basic Science(IBS-R034-D1)J.K.acknowledges the support from the National Research Foundation of Korea grants(NRF-2023R1A2C2007998)supported by the MSIT(Ministry of Science and ICT),Korea,under the ITRC(Information Technology Research Center)support program(IITP-2023-RS-2022-00164799)supervised by the IITP(Institute for Information&Communications Technology Planning&EvaluationM.T.,A.N.A.,and V.K.acknowledge support from the Priority 2030 Federal Academic Leadership Program(angle-resolved measurements)and the Russian Science Foundation,project 22-72-10047(sample fabrication).
文摘Dramatic fluorescence enhancement in two-dimensional(2D)van der Waals materials(vdWMs)coupled to plasmonic nanostructures has the potential to enable ultrathin,flexible,and high-brightness illumination devices.However,addressing the limitation of locally scattered small plasmon-enhanced areas remains challenging.Here,we present a 2D plasmonic enhancement of photoluminescence(PL)spanning nearly 800μm^(2),enabled by surface lattice resonance(SLR)in a 2D vdWM-Au slot lattice hybrid.The Au slot lattice is designed and fabricated using Babinet’s principle and Rayleigh’s anomaly to maximize radiative decay rate and induce non-local photo-excitation in a MoSe_(2)monolayer.For emitted PL coupled with SLR,enhanced by up to 32-fold,we investigate its in-plane directivity and long-range propagation using angle-and space-resolved spectroscopic PL measurements.Our experiment reveals that a nearly 800μm^(2)2D luminescent sheet can be achieved regardless of the size of the MoSe_(2)crystal,even with a sub-μm^(2)flake.This work provides a new type of ultrabright,large-area 2D luminescent material,suitable for a range of optical illumination,communication,and sensing devices.
基金supported by the Samsung Research Funding&Incubation Center of Samsung Electronics under Project Number SRFC-IT2401-01by National Research Foundation(NRF)grants(RS-2024-00462912 and RS-2023-00266110)funded by the Ministry of Science and ICT(MSIT)of the Korean governmentthe NRF Sejong Science Fellowship(RS-2021-NR061797)funded by the MSIT of the Korean government.
文摘Extending the depth of field(DOF)is essential for large-volume imaging in biological research,particularly in thick tissue environments.Bessel beams and their variants are widely used due to their simplicity and have been successfully applied to in vivo imaging.A recent advancement demonstrated the application of droplet Bessel beams(DBBs)for multi-photon microscopy,enabling functional imaging in live mouse brains.However,DBB generation inevitably requires active phase switching devices such as spatial light modulators,which reduce imaging speed and increase system complexity.This study introduces a droplet Bessel beam metalens(DBBM)that passively generates DBBs without phase switching by employing rectangular meta-atoms for orthogonal polarization modulation and X-shaped meta-atoms for amplitude control.Optical simulations identify optimal DBBM parameters that maximize the point spread function(PSF)aspect ratio while minimizing energy leakage into side lobes.Furthermore,the fabricated DBBM produces PSFs consistent with simulations.Imaging simulations based on three-dimensional confocal images of expansion microscopy-treated organoids demonstrated that the DBBM maintains superior performance even in the presence of aberrations.These findings establish the DBBM as a compact and passive solution for extended DOF imaging without the need for beam-shaping devices.Metalens technology is anticipated to have broad applications in real-time volumetric bioimaging and enable simplified optical system designs.
基金supported by the Samsung Research Funding&Incubation Center of Samsung Electronics under Project Number SRFC-IT2401-01 and by National Research Foundation(NRF)grants(RS-2024-00462912,RS-2023-00266110,and RS-2020-NR049544)funded by the Ministry of Science and ICT(MSIT)of the Korean governmentI.K.acknowledges the NRF Sejong Science Fellowship(RS-2021-NR061797)funded by the MSIT of the Korean government.
文摘Image scanning microscopy(ISM)is a promising imaging technique that offers sub-diffraction-limited resolution and optical sectioning.Theoretically,ISM can improve the optical resolution by a factor of two through pixel reassignment and deconvolution.Multifocal array illumination and scanning have been widely adopted to implement ISM because of their simplicity.Conventionally,digital micromirror devices(DMDs)1 and microlens arrays(MLAs)2,3 have been used to generate dense and uniform multifocal arrays for ISM,which are critical for achieving fast imaging and high-quality ISM reconstruction.However,these approaches have limitations in terms of cost,numerical aperture(NA),pitch,and uniformity,making it challenging to create dense and high-quality multifocal arrays at high NA.To overcome these limitations,we introduced a novel multifocal metalens design strategy called the hybrid multiplexing method,which combines two conventional multiplexing approaches:phase addition and random multiplexing.Through numerical simulations,we demonstrate that the proposed method generates more uniform and denser multifocal arrays than conventional methods,even at small pitches.As a proof of concept,we fabricated a multifocal metalens generating 40×40 array of foci with a 3μm pitch and NA of 0.7 operating at a wavelength of 488 nm and then constructed the multifocal metalens-based ISM(MMISM).We demonstrated that MMISM successfully resolved sub-diffraction-limited features in imaging of microbead samples and forebrain organoid sections.The results showed that MMISM imaging achieved twice the diffraction-limited resolution and revealed clearer structural features of neurons compared to wide-field images.We anticipate that our novel design strategy can be widely applied to produce multifunctional optical elements and replace conventional optical elements in specialized applications.
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This work was supported by the Samsung Research Funding&Incubation Center for Future Technology grant(SRFC-T1901-05)funded by Samsung Electronicsthe POSCO-POSTECH-RIST Convergence Research Center program funded by POSCO+3 种基金the National Research Foundation(NRF)grants(NRF-2019R1A2C3003129,CAMM-2019M3A683030637,NRF-2019R1A5A8080290,NRF-2020K1A3A1A21024374,NRF-2021K2A9A2A15000174,NRF-2021K1A3A 1A17086079)funded by the Ministry of Science and ICT(MSIT)of the Korean governmentY-KK acknowledges the NRF grants(NRF-2021R1A4A1030944,NRF.2021R1A2C2095010)funded by the MSIT of the Korean governmentJK acknowledges the POSTECH Alchemist fellowshiplK acknowledges the NRF Sejong Science fellowship(NRF-2021R1C1C2004291)funded by the MSIT of the Korean government.
文摘Taking inspiration from beautiful colors in nature,structural colors produced from nanostructured metasurfaces have shown great promise as a platform for bright,highly saturated,and high-resolution colors.Both plasmonic and dielectric materials have been employed to produce static colors that fulfil the required criteria for high-performance color printing,however,for practical applications in dynamic situations,a form of tunability is desirable.Combinations of the additive color palette of red,green,and blue enable the expression of further colors beyond the three primary colors,while the simultaneous intensity modulation allows access to the full color gamut.Here,we demonstrate an electrically tunable metasurface that can represent saturated red,green,and blue pixels that can be dynamically and continuously controlled between on and off states using liquid crystals.We use this to experimentally realize ultrahigh-resolution color printing,active multicolor cryptographic applications,and tunable pixels toward high-performance full-color reflective displays.
基金Hyundai Motor Group,Grant/Award Number:Hyundai Motor Chung Mong-Koo fellowshipLG Display,Grant/Award Number:LGD-SNU incubation programNational Research Foundation of Korea,Grant/Award Numbers:CAMM-2019M3A6B3030637,NRF-2019R1A2C3003129,NRF-2019R1A5A8080290,NRF-2021R1C1C2004291。
文摘Metasurfaces consisting of subwavelength structures,so-called meta-atoms,have steadily attracted considerable attention for advanced holography due to their advantages in terms of high-resolution holographic images,large field of view,and compact device volume.In contrast to conventional holographic displays using bulky conventional diffractive optical elements,metasurface holography enables arbitrary complex wavefront shaping with a much smaller footprint.In this review,we classify metasurface holography according to the meta-atom design methodologies,which can further expand hologram functionalities.We describe light-matter interactions,particularly in metasurface systems,using the relevant the Jones matrix to rigorously explain modulations of the amplitude,phase,and polarization of light.Six different types of metaatoms are presented,and the corresponding achievable wavefronts that form the holographic images in the far-field are also provided.Such a simple classification will give a straightforward approach to design and further realize advanced metasurface holographic devices.
基金supports from the National Natural Science Foundation of China(Numbers 11574240 and 11774273)the Outstanding Youth Funds of Hubei Province(Number 2016CFA034)+4 种基金the Open Foundation of State Key Laboratory of Optical Communication Technologies and Networks,Wuhan Research Institute of Posts and Telecommunications(Number OCTN-201605)the financial supports from the Postdoctoral Innovation Talent Support Program of China(BX20180221)the Global Ph.D.fellowship from the Korean government(NRF-2016H1A2A1906519)the financial support from the National Research Foundation(NRF)grants(NRF-2017R1E1A1A03070501,NRF-2017R1E1A2A01076613,NRF-2018M3D1A1058998,NRF-2015R1A5A1037668,and CAMM-2014M3A6B3063708)funded by the Ministry of Science and ICT(MSIT)of the Korean governmentthe financial support from the National Research Foundation,Prime Minister’s Office,Singapore under its Competitive Research Program(CRP award NRF CRP15-2015-03).
文摘With the rapid progress in computer science,including artificial intelligence,big data and cloud computing,full-space spot generation can be pivotal to many practical applications,such as facial recognition,motion detection,augmented reality,etc.These opportunities may be achieved by using diffractive optical elements(DOEs)or light detection and ranging(LIDAR).However,DOEs suffer from intrinsic limitations,such as demanding depth-controlled fabrication techniques,large thicknesses(more than the wavelength),Lambertian operation only in half space,etc.LIDAR nevertheless relies on complex and bulky scanning systems,which hinders the miniaturization of the spot generator.Here,inspired by a Lambertian scatterer,we report a Hermitian-conjugate metasurface scrambling the incident light to a cloud of random points in full space with compressed information density,functioning in both transmission and reflection spaces.Over 4044 random spots are experimentally observed in the entire space,covering angles at nearly 90°.Our scrambling metasurface is made of amorphous silicon with a uniform subwavelength height,a nearly continuous phase coverage,a lightweight,flexible design,and low-heat dissipation.Thus,it may be mass produced by and integrated into existing semiconductor foundry designs.Our work opens important directions for emerging 3D recognition sensors,such as motion sensing,facial recognition,and other applications.
基金This work was financially supported by the LGD-SNU incubation program funded by LG Display and the National Research Foundation of Korea(NRF)grants(NRF-2019R1A2C3003129,CAMM-2019M3A6B3030637,NRF-2019R1A5A8080290)funded by the Ministry of Science and ICT(MSIT)of the Korean government.M.Q.M acknowledges a research grant by Higher Education Commission(HEC)of Pakistan through National Research Program for Universities(NRPU)[Project No.10177/Punjab/NRPU/R&D/HEC/2017]to support this work.M.Q.M.,T.T.,K.R.,U.Y.,and M.Z.acknowledge their internal research grants from ITU.M.A.A.acknowledges the Pre-Doctoral Fellowship from ITU.I.K.acknowledges the NRF Sejong Science fellowship(NRF-2021R1C1C2004291)funded by the MSIT of the Korean government.
文摘Helicity-multiplexed metasurfaces based on symmetric spin–orbit interactions (SOIs) have practical limits because they cannot provide central-symmetric holographic imaging. Asymmetric SOIs can effectively address such limitations, with several exciting applications in various fields ranging from asymmetric data inscription in communications to dual side displays in smart mobile devices. Low-loss dielectric materials provide an excellent platform for realizing such exotic phenomena efficiently. In this paper, we demonstrate an asymmetric SOI-dependent transmission-type metasurface in the visible domain using hydrogenated amorphous silicon (a-Si:H) nanoresonators. The proposed design approach is equipped with an additional degree of freedom in designing bi-directional helicity-multiplexed metasurfaces by breaking the conventional limit imposed by the symmetric SOI in half employment of metasurfaces for one circular handedness. Two on-axis, distinct wavefronts are produced with high transmission efficiencies, demonstrating the concept of asymmetric wavefront generation in two antiparallel directions. Additionally, the CMOS compatibility of a-Si:H makes it a cost-effective alternative to gallium nitride (GaN) and titanium dioxide (TiO2) for visible light. The cost-effective fabrication and simplicity of the proposed design technique provide an excellent candidate for high-efficiency, multifunctional, and chip-integrated demonstration of various phenomena.
基金Samsung Research Funding&Incubation Center for Future Technology(SRFC-IT1901-05)。
文摘Structural coloration techniques have improved display science due to their high durability in terms of resistance to bleaching and abrasion,and low energy consumption.Here,we propose and demonstrate an all-solid-state,large-area,lithography-free color filter that can switch structural color based on a doped semiconductor.Particularly,an indium-gallium-zinc-oxide(IGZO)thin film is used as a passive index-changing layer.The refractive index of the IGZO layer is tuned by controlling the charge carrier concentration;a hydrogen plasma treatment is used to control the conductivity of the IGZO layer.In this paper,we verify the color modulation using finite difference time domain simulations and experiments.The IGZO-based color filter technology proposed in this study will pave the way for charge-controlled tunable color filters displaying a wide gamut of colors on demand.
基金POSCO(POSCO-POSTECH-RIST Convergence Research Center program)National Research Foundation of Korea(CAMM-2019M3A6B3030637,NRF-2019R1A2C3003129,NRF-2019R1A5A8080290)+3 种基金Higher Education Commision,Pakistan(10177/Punjab/NRPU/RD/HEC/2017)H.S.K.acknowledges the Ph.D.fellowship grant(PhDEE 17003)by ITU LahorePakistan.I.K.acknowledges the NRF Sejong Science fellowship(NRF-2021R1C1C2004291)funded by the Ministry of ScienceICT of the Korean government.T.L.acknowledges the NRF Global Ph.D.fellowship(NRF-2019H1 A2A 1076295)funded by the Ministry of Education of the Korean government.Y.K.acknowledges the Hyundai Motor Chung Mong-Koo fellowship and the POSTECHIAN fellowship.J.K.acknowledges the POSTECH Alchemist fellowship.M.Q.M.,M.Z.,and K.R.acknowledge an internal research grant by ITU Lahore,Pakistan.
文摘Chiro-optical effects offer a wide range of potential applications in nanophotonics,such as advanced imaging and molecular sensing and separation.Flat single-layer metasurfaces composed of subwavelength meta-atoms have gained significant attention due to their exceptional characteristics in light–matter interactions.Although metasurface-based devices have manipulated electromagnetic waves,the compact on-chip realization of giant chiro-optical effects remains a challenge at optical frequencies.In this work,we experimentally and numerically demonstrate an all-dielectric metasurface to realize large chiro-optical effects in the visible regime.Notably,the proposed strategy of utilizing achiral nanofins instead of conventional chiral structures provides an extra degree of design freedom.The mutual coupling between carefully engineered nanofins produces constructive and destructive interference,leading to the asymmetric transmission of 70%and average circular dichroism exceeding 60%.We investigate the underlying mechanism behind the chiro-optical effects using the theory of multipolar decomposition.The proposed design mechanism maximizes the chiro-optical response through a single-layer metasurface with potential applications in high-efficiency integrated ultrathin polarization rotators and shapers,chiral polarizers for optical displays,chiral beam splitters,and chiral sensors.
基金This work was financially supported by the National Research Foundation(NRF)grants(NRF-2019R1A2C3003129,CAMM-2019M3A6B3030637,NRF-2019R1A5A8080290,NRF-2018M3D1A1058998)the Ministry of Science and ICT(MSIT)of the Korean government.I.K.acknowledges the Global Ph.D.fellowship(NRF-2016H1A2A1906519)the NRF-MSIT of the Korean government.Y.Y.acknowledges a fellowship from the Hyundai Motor Chung Mong-Koo Foundation.
文摘The capillary force effect is one of the most important fabrication parameters that must be considered at the micro/nanoscale because it is strong enough to deform micro/nanostructures.However,the deformation of micro/nanostructures due to such capillary forces(e.g.,stiction and collapse)has been regarded as an undesirable and uncontrollable obstacle to be avoided during fabrication.Here,we present a capillary-force-induced collapse lithography(CCL)technique,which exploits the capillary force to precisely control the collapse of micro/nanostructures.CCL uses electron-beam lithography,so nanopillars with various shapes can be fabricated by precisely controlling the capillary-force-dominant cohesion process and the nanopillar-geometry-dominant collapse process by adjusting the fabrication parameters such as the development time,electron dose,and shape of the nanopillars.CCL aims to achieve sub-10-nm plasmonic nanogap structures that promote extremely strong focusing of light.CCL is a simple and straightforward method to realize such nanogap structures that are needed for further research such as on plasmonic nanosensors.
基金National Research Foundation of Korea(2023R1A2C2002777)KIST Institutional Program(Atmospheric Environment Research Program)(2E32302)BK FOUR。
文摘We experimentally demonstrate an all-pass microring resonator (MRR) based on a Y_(2)O_(3)BOX germanium-oninsulator (GeOI) platform operating in the mid-IR region.The ring resonator was numerically designed to have a high quality (Q) factor in the 4.18μm to 4.22μm wavelength range in the fundamental TE mode.According to our design,the GeOI ring resonator was fabricated by the direct wafer-bonding technology with an yttria(Y_(2)O_(3)) buried oxide layer,which is transparent at the mid-IR region,for the bonding interface and the electron beam lithography.The experimental resonant characteristic was obtained using our fiber-based mid-IR measurement setup.The GeOI single MRR exhibited an extinction ratio (ER) of 15.28 dB and an insertion loss (IL)of 1.204 dB,and the racetrack showed an ER of 22.77 dB and an IL of 0.627 dB.Furthermore,the free spectral range of the device was 5.29 nm,and the loaded Q factor of 94,528 (176,158 of intrinsic Q factor) was extracted by the nonlinear least squares method.We believe this demonstration of our GeOI MRR offers a valuable opportunity to implement multipurpose devices such as optical sensors,switches,and filters in the mid-IR range.
基金financially supported by National Research Foundation(NRF)grants(RS-2023-00266110,NRF-2020R1A5A1019649,NRF-2022M3C1A3081312,and NRF-2023M3K5A109482011)funded by the Ministry of Science and ICT(MSIT)of the Korean governmentI.Kim ac-knowledges the NRF Sejong Science Fellowship(NRF-2021R1C1C2004291)funded by the MSIT of the Korean government.
文摘Advanced imaging techniques have been widely used in various biological studies.Currently,numerous imaging modalities are utilized in biological applications,including medical imaging,diagnosis,biometrics,and fundamental biological research.Consequently,the demand for faster,clearer,and more accurate imaging techniques to support sophisticated biological studies has increased.However,there is a limitation in enhancing performance of imaging devices owing to the system complexity associated with bulky conventional optical elements.To address this issue,metasurfaces,which are flat and compact optical elements,have been considered potential candidates for biological imaging.Here,we comprehensively discuss the metasurface empowered various imaging applications in biology,including their working principles and design strategies.Furthermore,we compared conventional imaging modalities with the metasurface-based imaging system.Finally,we discuss the current challenges and offer future perspectives on metasurfaces.
文摘Infrared chiral plasmonic metamaterials based on perpendicularly positioned nanorods enable surface-enhanced vibrational circular dichroism for more selective and sensitive identification of protein fingerprints and enantioselective sensing,which creates a new pathway for chemical or biomedical applications.
