Interaction between photons and phonons in cavity optomechanical systems provides a new toolbox for quantum information technologies.A GaAs/AlAs pillar multi-optical mode microcavity optomechanical structure can obtai...Interaction between photons and phonons in cavity optomechanical systems provides a new toolbox for quantum information technologies.A GaAs/AlAs pillar multi-optical mode microcavity optomechanical structure can obtain phonons with ultra-high frequency(~THz).However,the optical field cannot be effectively restricted when the diameter of the GaAs/AlAs pillar microcavity decreases below the diffraction limit of light.Here,we design a system that combines Ag nanocav-ity with GaAs/AlAs phononic superlattices,where phonons with the frequency of 4.2 THz can be confined in a pillar with~4 nm diameter.The Q_(c)/V reaches 0.22 nm^(-3),which is~80 times that of the photonic crystal(PhC)nanobeam and~100 times that of the hybrid point-defect PhC bowtie plasmonic nanocavity,where Q_(c) is optical quality factor and V is mode volume.The optome-chanical single-photon coupling strength can reach 12 MHz,which is an order of magnitude larger than that of the PhC nanobeam.In addition,the mechanical zero-point fluctuation amplitude is 85 fm and the efficient mass is 0.27 zg,which is much smaller than the PhC nanobeam.The phononic superlattice-Ag nanocavity optomechanical devices hold great potential for applications in the field of integrated quantum optomechanics,quantum information,and terahertz-light transducer.展开更多
Efficient thermal radiation in the mid-infrared(M-IR)region is of supreme importance for many applications including thermal imaging and sensing,thermal infrared light sources,infrared spectroscopy,emissivity coatings...Efficient thermal radiation in the mid-infrared(M-IR)region is of supreme importance for many applications including thermal imaging and sensing,thermal infrared light sources,infrared spectroscopy,emissivity coatings,and camouflage.The ability to control light makes metasurfaces an attractive platform for infrared applications.Recently,different metamaterials have been proposed to achieve high thermal radiation.To date,broadening the radiation bandwidth of a metasurface emitter(meta-emitter)has become a key goal to enable extensive applications.We experimentally demonstrate a broadband M-IR thermal emitter using stacked nanocavity metasurface consisting of two pairs of circular-shaped dielectric(Si;N;)–metal(Au)stacks.A high thermal radiation can be obtained by engineering the geometry of nanocavity metasurfaces.Such a meta-emitter provides wideband and broad angular absorptance of both p-and s-polarized light,offering a wideband thermal radiation with an average emissivity of more than 80%in the M-IR atmospheric window of 8–14μm.The experimental illustration together with the theoretical framework establishes a basis for designing broadband thermal emitters,which,as anticipated,will initiate a promising avenue to M-IR sources.展开更多
Silicon-based electro-optic modulators are the key devices in integrated optoelectronics. Integration of the graphene layer and the photonic crystal(PC) cavity is a promising way of achieving compact modulators with h...Silicon-based electro-optic modulators are the key devices in integrated optoelectronics. Integration of the graphene layer and the photonic crystal(PC) cavity is a promising way of achieving compact modulators with high efficiency. In this paper, a high-quality(Q) acceptor-type PC nanocavity is employed to integrate with a single-layer graphene for realizing strong modulation. Through tuning the chemical potential of graphene, a large wavelength shift of 2.62 nm and a Q factor modulation of larger than 5 are achieved. A modulation depth(12.8 dB) of the reflection spectrum is also obtained.Moreover, the optimized PC nanocavity has a large free spectral range of 131.59 nm, which can effectively enhance the flexibility of the modulator. It shows that the proposed graphene-based PC nanocavity is a potential candidate for compact,high-contrast, and low-power absorptive modulators in integrated silicon chips.展开更多
By utilizing a Fabry–Perot (FP) nanocavity adjacent to T-shaped gap waveguide ports, spectrally selective filtering is realized. When the wavelength of incident light corresponds to the resonance wavelength of the ...By utilizing a Fabry–Perot (FP) nanocavity adjacent to T-shaped gap waveguide ports, spectrally selective filtering is realized. When the wavelength of incident light corresponds to the resonance wavelength of the FP nanocavity, the surface plasmons are captured inside the nanocavity, and light is highly reflected from this port. The resonance wavelength is determined by using Fabry–Perot resonance condition for the nanocavity. For any desired filtering frequency the dimension of the nanocavity can be tailored. The numerical results are based on the two-dimensional finite difference time domain simulation under a perfectly matched layer absorbing boundary condition. The analytical and simulation results indicate that the proposed structure can be utilized for filtering and splitting applications.展开更多
The strongly coupled system composed of atoms,molecules,molecule aggregates,and semiconductor quantum dots embedded within an optical microcavity/nanocavity with high quality factor and/or low modal volume has become ...The strongly coupled system composed of atoms,molecules,molecule aggregates,and semiconductor quantum dots embedded within an optical microcavity/nanocavity with high quality factor and/or low modal volume has become an excellent platform to study cavity quantum electrodynamics(CQED),where a prominent quantum effect called Rabi splitting can occur due to strong interaction of cavity-mode single-photon with the two-level atomic states.In this paper,we build a new quantum model that can describe the optical response of the strongly-coupled system under the action of an external probing light and the spectral lineshape.We take the Hamiltonian for the strongly-coupled photon-atom system as the unperturbed Hamiltonian H_(0)and the interaction Hamiltonian of the probe light upon the coupled-system quantum states as the perturbed Hamiltonian V.The theory yields a double Lorentzian lineshape for the permittivity function,which agrees well with experimental observation of Rabi splitting in terms of spectral splitting.This quantum theory will pave the way to construct a complete understanding for the microscopic strongly-coupled system that will become an important element for quantum information processing,nano-optical integrated circuits,and polariton chemistry.展开更多
Herein,we propose a high-quality(Q) factor hybrid plasmonic nanocavity based on distributed Bragg reflectors(DBRs) with low propagation loss and extremely strong mode confinement.This hybrid plasmonic nanocavity i...Herein,we propose a high-quality(Q) factor hybrid plasmonic nanocavity based on distributed Bragg reflectors(DBRs) with low propagation loss and extremely strong mode confinement.This hybrid plasmonic nanocavity is composed of a high-index cylindrical nanowire separated from a metal surface possessing shallow DBRs gratings by a sufficiently thin low-index dielectric layer.The hybrid plasmonic nanocavity possesses advantages such as a high Purcell factor(Fp) of up to nearly 20000 and a gain threshold approaching 266 cm^(-1)at 1550 nm,promising a greater potential in deep sub-wavelength lasing applications.展开更多
The single and coupled photonic crystal nanocavity lasers are fabricated in the InGaAsP material system and their static and dynamic features are compared. The coupled-cavity lasers show a larger lasing e^ciency and g...The single and coupled photonic crystal nanocavity lasers are fabricated in the InGaAsP material system and their static and dynamic features are compared. The coupled-cavity lasers show a larger lasing e^ciency and generate an output power higher than the single-cavity lasers, results that are consistent with the theoretical results obtained by rate equations. In dynamic regime, the single-cavity lasers produce pulses as short as 113 ps, while the coupled-cavity lasers show a significantly longer lasing duration. These results indicate that the photonic crystal laser is a promising candidate for the light source in high-speed photonic integrated circuit.展开更多
Localized surface plasmon resonances(LSPR)generated in a particle-film nanocavity enhance electric fields within a nanoscale volume.LSPR can also decay into hot carriers,highly energetic species that catalyze photocat...Localized surface plasmon resonances(LSPR)generated in a particle-film nanocavity enhance electric fields within a nanoscale volume.LSPR can also decay into hot carriers,highly energetic species that catalyze photocatalytic reactions in molecular analytes located in close proximity to metal surfaces.In this study,we examined the intensity of the electric field(near-field)and photocatalytic properties of plasmonic nanocavities formed by single nanoparticles(SNP)on single nanoplates(SNL).Using 4-nitrobenzenethiol(4-NBT)as a molecular reporter,we determined the near-field responses,as well as measured rates of 4-NBT dimerization into 4,4-dimercaptoazobenzene(DMAB)in the gold(Au)SNP on AuSNL nanocavity(Au-Au),as well as in AuSNP on AgSNL(Au-Ag),AgSNP on AuSNL(Ag-Au),and AgSNP on AgSNL(Ag-Ag)nanocavities using 532,660,and 785 nm excitations.We observed the strongest near-field signals of 4-NBT at 660 nm in all examined plasmonic systems that is found to be substantially red-shifted relative to the LSPR of the corresponding nanoparticles.We also found that rates of DMAB formation were significantly greater in heterometal nanocavities(Au-Ag and Ag-Au)compared to their monometallic counterparts(Au-Au and Ag-Ag).These results point to drastic differences in plasmonic and photocatalytic properties of mono and bimetallic nanostructures.展开更多
Simultaneous localization of light to extreme spatial and spectral scales is of high importance for testing fundamental physics and various applications.However,there is a longstanding trade-off between localizing a l...Simultaneous localization of light to extreme spatial and spectral scales is of high importance for testing fundamental physics and various applications.However,there is a longstanding trade-off between localizing a light field in space and in frequency.Here we discover a new class of twisted lattice nanocavities based on mode locking in momentum space.The twisted lattice nanocavity hosts a strongly localized light field in a 0.048𝜆3 mode volume with a quality factor exceeding 2.9×1011(∼250𝜇s photon lifetime),which presents a record high figure of merit of light localization among all reported optical cavities.Based on the discovery,we have demonstrated silicon-based twisted lattice nanocavities with quality factor over 1 million.Our result provides a powerful platform to study light-matter interaction in extreme conditions for tests of fundamental physics and applications in nanolasing,ultrasensing,nonlinear optics,optomechanics and quantum-optical devices.展开更多
Whispering-gallery-mode(WGM) hexagonal optical micro-/nanocavities can be utilized as high-quality(Q) resonators for realizing compact-size low-threshold lasers. In this paper, the progress in WGM hexagonal micro-/nan...Whispering-gallery-mode(WGM) hexagonal optical micro-/nanocavities can be utilized as high-quality(Q) resonators for realizing compact-size low-threshold lasers. In this paper, the progress in WGM hexagonal micro-/nanocavity lasers is reviewed comprehensively. High-Q WGMs in hexagonal cavities are divided into two kinds of resonances propagating along hexagonal and triangular periodic orbits, with distinct mode characteristics according to theoretical analyses and numerical simulations;however, WGMs in a wavelength-scale nanocavity cannot be well described by the ray model. Hexagonal micro-/nanocavity lasers can be constructed by both bottom-up and top-down processes, leading to a diversity of these lasers. The ZnO-or nitride-based semiconductor material generally has a wurtzite crystal structure and typically presents a natural hexagonal cross section. Bottom-up growth guarantees smooth surface faceting and hence reduces the scattering loss effectively.Laser emissions have been successfully demonstrated in hexagonal micro-/nanocavities synthesized with various materials and structures. Furthermore, slight deformation can be easily introduced and precisely controlled in top-down fabrication, which allows lasing-mode manipulation. WGM lasing with excellent singletransverse-mode property was realized in waveguide-coupled ideal and deformed hexagonal microcavity lasers.展开更多
The coherent light-matter interaction has drawn an enormous amount of attention for its fundamental importance in the cavity quantum-electrodynamics (C-QED) field and great potential in quantum information application...The coherent light-matter interaction has drawn an enormous amount of attention for its fundamental importance in the cavity quantum-electrodynamics (C-QED) field and great potential in quantum information applications. Here, we design a hybrid C-QED system consisting of a quantum dot (QD) driven by two-tone fields implanted in a photonic crystal (PhC) cavity coupled to an auxiliary cavity with a single-mode waveguide and investigate the hybrid system operating in the weak, intermediate, and strong coupling regimes of the light-matter interaction via comparing the QD-photon interaction with the dipole decay rate and the cavity field decay rate.The results indicate that the auxiliary cavity plays a key role in the hybrid system, which affords a quantum channel to influence the absorption of the probe field. By controlling the coupling strength between the auxiliary cavity and the PhC cavity, the phenomenon of the Mollow triplet can appear in the intermediate coupling regime,and even in the weak coupling regime. We further study the strong coupling interaction manifested by vacuum Rabi splitting in the absorption with manipulating the cavity-cavity coupling under different parameter regimes.This study provides a promising platform for understanding the dynamics of QD-C-QED systems and paving the way toward on-chip QD-based nanophotonic devices.展开更多
Surface energy plays an important role in the mechanical performance of nanomaterials; however, determining the surface energy density of curved surfaces remains a challenge. In this paper, we conduct atomic simulatio...Surface energy plays an important role in the mechanical performance of nanomaterials; however, determining the surface energy density of curved surfaces remains a challenge. In this paper, we conduct atomic simulations to calculate the surface energy density of spherical surfaces in various crystalline metals. It is found that the average surface energy density of spherical surfaces remains almost constant once its radius exceeds 5 nm. Then, using a geometrical analysis and the scaling law, we develop an analytical approach to estimate the surface energy density of spherical surfaces through that of planar surfaces. The theoretical prediction agrees well with the direct atomic simulations, and thus provides a simple and general method to calculate the surface energy density in crystals.展开更多
The enhancement characteristics of the local field in the surface plasmon nanocavities are investigated numerically. The cavity is constructed by placing a defect structure in the thickness-modulated metal-insulator-m...The enhancement characteristics of the local field in the surface plasmon nanocavities are investigated numerically. The cavity is constructed by placing a defect structure in the thickness-modulated metal-insulator-metal waveguide Bragg gratings. The characteristic impedance based transfer matrix method is used to calculate the transmission spectra and the resonant wavelength of the cavities with various geometric parameters. The finite-difference time- domain method is used to obtain the field pattern of the resonant mode and validate the results of the transfer matrix method. The calculation and simulation results reveal the existence of resonant wavelength shift and intensity variation with structural parameters, such as the modulation period of the gratings, the length and the width of the defect structure. Both numerical analysis and theoretical interpretation on these phenomena are given in details.展开更多
With nanovoids buried in Co films, resonant structures were observed in spectra of polar magneto-optical Kerr effect(MOKE), where both a narrow bandwidth and high intensity were acquired. Through changing the thickn...With nanovoids buried in Co films, resonant structures were observed in spectra of polar magneto-optical Kerr effect(MOKE), where both a narrow bandwidth and high intensity were acquired. Through changing the thickness of Co films and the lattice of voids, different optical modes were introduced. For a very shallow array of voids, the resonant MOKE was induced by Ag plasma edge resonance, for deeper ones, hybrid plasma modes, such as void plasmons in the voids, surface lattice plasmons between the voids, and the co-action of them, etc. resulted in resonant MOKE. We found that resonant MOKE resulted from the void plasmons resonance which possesses the narrowest bandwidth for the lowest absorption of voids. The simulated electromagnetic field(EF) distribution consolidated different effects of these three optical modes on resonant MOKE modulation. Such resonant polar MOKE possesses high sensitivity, which might pave the way to on-chip MO devices.展开更多
Developing a convenient method to endow bulk Cu-based electrode with high activity of electrocatalytic CO_(2)reduction reaction(CO_(2)RR)to multicarbon(C_(2+))products is desirable but challenging.Herein,for the first...Developing a convenient method to endow bulk Cu-based electrode with high activity of electrocatalytic CO_(2)reduction reaction(CO_(2)RR)to multicarbon(C_(2+))products is desirable but challenging.Herein,for the first time,we report that mechanical polishing induces highly reactive Cu sites for selective C-C coupling in CO_(2)RR.We find that mechanical polishing could endow Cu foil with abundant nanocavity surface structure,which efficiently confines the carbonaceous intermediates to enhance the probability of C-C coupling reaction.By confining the carbonaceous intermediates with Cu nanocavity,the as-prepared electrode delivers a Faradaic efficiency toward C_(2+)products of 65.7%at-1.3 V vs.RHE,which is enhanced up to 1.7 folds compared with that of commercial Cu foil.This work provides a new method to enable Cu foil with high activity of CO_(2)RR to C_(2+)products.展开更多
A horizontally slotted photonic crystal nanobeam cavity with an embedded active nanopillar structure is proposed for ultrafast direct modulation. By designing the thicknesses of both the nanobeam and the horizontal sl...A horizontally slotted photonic crystal nanobeam cavity with an embedded active nanopillar structure is proposed for ultrafast direct modulation. By designing the thicknesses of both the nanobeam and the horizontal slot layer, the quality factor (Q factor) and the mode volume (Vn) of the proposed cavity can be engineered independently. As a result, the spontaneous emission (SpE) rate is enhanced with a small Vn of 2.4 while the SpE rate and the cavity photon lifetime have an optimal Q factor of ~ 1000. In our simulation, the modulation bandwidth could be enhanced up to 170 GHz with different emission linewidths nf the~ netiv~ nnnnnillnr展开更多
Reducing kinetic energy barriers and developing accessible active sites are critical to deliver high hydrogen evolution reaction(HER)efficiency.In this paper,we synthesized defect-modulated and heteroatom(boron)-funct...Reducing kinetic energy barriers and developing accessible active sites are critical to deliver high hydrogen evolution reaction(HER)efficiency.In this paper,we synthesized defect-modulated and heteroatom(boron)-functionalized three-dimensional(3D)bowl-shaped Ti_(3−x)C_(2)T_(y)MXene(B-TCT)nanocavities coupled with the vertical growth of MoSe_(2)nanoflakes.The B-TCT@MoSe_(2)nanohybrids catalyst delivers the overpotentials of 49.9,52.7,and 67.8 mV to reach a HER current density of 10 mA·cm^(−2)under acidic,alkaline,and neutral conditions,respectively.Such outstanding HER activity is predominantly attributed to the heteroatom functionalization,self-adapting Ti vacancy(VTi)defect modulation,and spatial configuration design in the 3D B-TCT nanocavity,which synergistically regulate the electronic structure,activate the basal plane/edge unsaturated sites,and reduce the reaction energy barrier.Experimental and theoretical calculations demonstrate that strong heterogeneous interfacial bonding interactions between B-TCT and MoSe_(2)can dramatically reduce the free energy of hydrogen adsorption and facilitate efficient interfacial charge migration,thus essentially improving the HER kinetics.We used this 3D porous nanohybrid system assembled by defectrich lamellar structures to elucidate the advantageous synergistic effects of multiple mechanisms among defect structure,heteroatom functionalization,and interfacial coupling,which provided important insights for the development of efficient hybridtype catalysts.展开更多
Polarization-sensitive photodetectors based on two-dimensional(2D)materials have shown more attractive application prospects compared to traditional thin-film photodetectors due to their atomic thickness,tunable bandg...Polarization-sensitive photodetectors based on two-dimensional(2D)materials have shown more attractive application prospects compared to traditional thin-film photodetectors due to their atomic thickness,tunable bandgap,high mobility and strong light-matter interactions.Among them,2D molybdenum disulfide(MoS_(2))has drawn numerous attentions in photodetection due to its wide spectral range,remarkable photoresponsivity and fast photo-switching rate.However,the isotropic crystal structure of MoS_(2)hampers its application in the polarization-sensitive detection,which is highly desired in military and civilian applications.In this paper,we demonstrated an integration of plasmonic nanocavity with monolayer MoS_(2)to achieve high photoresponsivity and polarization-sensitive photodetector.With the significant enhancement of electromagnetic field provided by the gap-surfaceplasmon(GSP),we achieved a significant photoluminescence(PL)enhancement of 24-fold.Relying on the enhanced light absorption by our plasmonic nanocavity,which generally facilitates photo-generation of electron-hole pairs in MoS_(2),we achieved a high photoresponsivity of 1.88 A/W and degree of linear polarization(DOLP)of 0.8 at the excitation wavelength of 633 nm.Our work provides a feasible and universal solution to realize polarization-sensitive photodetector of MoS_(2)for high-performance and polarization-sensitive photodetectors.展开更多
Mixed matrix membranes(MMMs)with the performance between the matrix and the filler is a promising strategy for membranes with excellent gas permeability-selectivity.In this study,the hollow polydimethylsiloxane nanopa...Mixed matrix membranes(MMMs)with the performance between the matrix and the filler is a promising strategy for membranes with excellent gas permeability-selectivity.In this study,the hollow polydimethylsiloxane nanoparticles were synthesized and then incorporated with the poly(oxide ethylene)monomer and tri-functional cross-linker to form mixed matrix membranes by in situ poly-merization.The hollow nanoparticles formed the independent closed nanocavities in membranes,which enhanced the gas permeability contributed by both the improved diffusivity and solubility.At high loading,the hollow polydimethylsiloxane nanoparticle was converted into the continuous phase with the cross-linked poly(oxide ethylene)as the dispersed phase.Gases preferred to permeate through the connected cluster of hollow polydimethylsiloxane nanoparticles,finally leading to ultrahigh gas per-meabilities far going beyond the instinct values of polydimethylsiloxane and the cross-linked poly(oxide ethylene).The optimized membrane with 34 wt%hollow nanoparticles loadings exhibited ultrahigh permeabilities with the values of 44186 Barrer for CO_(2) and 11506 Barrer for O_(2),accompanied with a CO_(2)/N_(2) selectivity of 9.9 and an O_(2)/N_(2) selectivity of 2.6,which exceeded the 2008 Robeson upper bound for O_(2)/N_(2) and located at the 2008 Robeson upper bound for CO_(2)/N_(2).展开更多
Monolayer graphene has attracted enormous attention owing to its unique electronic and optical properties.However,achieving an effective approach without applying electrical bias for manipulating the charge transfer b...Monolayer graphene has attracted enormous attention owing to its unique electronic and optical properties.However,achieving an effective approach without applying electrical bias for manipulating the charge transfer based on graphene is elusive to date.Herein,we realized the manipulation of excitons’transition from emitter to the graphene surface with plasmonic engineering nanostructures and firstly obtained large enhancements for photon emission on the graphene surface.The localized plasmons generated from the plasmonic nanostructures of shell-isolated nanoparticle coupling to ultra-flat Au substrate would dictate a consistent junction geometry while enhancing the optical field and dominating the electron transition pathways,which may cause obvious perturbations for molecular radiation behaviors.Additionally,the three-dimensional finite-difference time-domain and time-dependent density functional theory were also carried out to simulate the distributions of electromagnetic field and energy levels of hybrid nanostructure respectively and the results agreed well with the experimental data.Therefore,this work paves a novel approach for tunning graphene charge/energy transfer processes,which may hold great potential for applications in photonic devices based on graphene.展开更多
基金J.Z.acknowledges National Natural Science Foundation of China(12074371)CAS Interdisciplinary Innovation Team,Strategic Priority Research Program of Chinese Academy of Sciences(XDB28000000)Key-Area Research and Development Program of Guangdong Province(Grant No.2018B030329001).
文摘Interaction between photons and phonons in cavity optomechanical systems provides a new toolbox for quantum information technologies.A GaAs/AlAs pillar multi-optical mode microcavity optomechanical structure can obtain phonons with ultra-high frequency(~THz).However,the optical field cannot be effectively restricted when the diameter of the GaAs/AlAs pillar microcavity decreases below the diffraction limit of light.Here,we design a system that combines Ag nanocav-ity with GaAs/AlAs phononic superlattices,where phonons with the frequency of 4.2 THz can be confined in a pillar with~4 nm diameter.The Q_(c)/V reaches 0.22 nm^(-3),which is~80 times that of the photonic crystal(PhC)nanobeam and~100 times that of the hybrid point-defect PhC bowtie plasmonic nanocavity,where Q_(c) is optical quality factor and V is mode volume.The optome-chanical single-photon coupling strength can reach 12 MHz,which is an order of magnitude larger than that of the PhC nanobeam.In addition,the mechanical zero-point fluctuation amplitude is 85 fm and the efficient mass is 0.27 zg,which is much smaller than the PhC nanobeam.The phononic superlattice-Ag nanocavity optomechanical devices hold great potential for applications in the field of integrated quantum optomechanics,quantum information,and terahertz-light transducer.
基金support from the National Key Research and Development Program of China(2019YFA0709100,2020YFA0714504)Fundamental Research Funds for the Central Universities(Nos.DUT20GF108,DUT20RC(3)007,DUT20RC(3)062,DUT19RC(3)010)the Program for Liaoning excellent Talents in University(Grant No.LJQ2015021)。
文摘Efficient thermal radiation in the mid-infrared(M-IR)region is of supreme importance for many applications including thermal imaging and sensing,thermal infrared light sources,infrared spectroscopy,emissivity coatings,and camouflage.The ability to control light makes metasurfaces an attractive platform for infrared applications.Recently,different metamaterials have been proposed to achieve high thermal radiation.To date,broadening the radiation bandwidth of a metasurface emitter(meta-emitter)has become a key goal to enable extensive applications.We experimentally demonstrate a broadband M-IR thermal emitter using stacked nanocavity metasurface consisting of two pairs of circular-shaped dielectric(Si;N;)–metal(Au)stacks.A high thermal radiation can be obtained by engineering the geometry of nanocavity metasurfaces.Such a meta-emitter provides wideband and broad angular absorptance of both p-and s-polarized light,offering a wideband thermal radiation with an average emissivity of more than 80%in the M-IR atmospheric window of 8–14μm.The experimental illustration together with the theoretical framework establishes a basis for designing broadband thermal emitters,which,as anticipated,will initiate a promising avenue to M-IR sources.
基金supported by the National Natural Science Foundation of China (Grant No. 11674273)the Science and Technology Plan Projects of Colleges and Universities of Shandong Province,China (Grant No. J15LJ52)。
文摘Silicon-based electro-optic modulators are the key devices in integrated optoelectronics. Integration of the graphene layer and the photonic crystal(PC) cavity is a promising way of achieving compact modulators with high efficiency. In this paper, a high-quality(Q) acceptor-type PC nanocavity is employed to integrate with a single-layer graphene for realizing strong modulation. Through tuning the chemical potential of graphene, a large wavelength shift of 2.62 nm and a Q factor modulation of larger than 5 are achieved. A modulation depth(12.8 dB) of the reflection spectrum is also obtained.Moreover, the optimized PC nanocavity has a large free spectral range of 131.59 nm, which can effectively enhance the flexibility of the modulator. It shows that the proposed graphene-based PC nanocavity is a potential candidate for compact,high-contrast, and low-power absorptive modulators in integrated silicon chips.
基金Project supported by the National Key Basic Research Program of China (Grant No. 2013CB328702)
文摘By utilizing a Fabry–Perot (FP) nanocavity adjacent to T-shaped gap waveguide ports, spectrally selective filtering is realized. When the wavelength of incident light corresponds to the resonance wavelength of the FP nanocavity, the surface plasmons are captured inside the nanocavity, and light is highly reflected from this port. The resonance wavelength is determined by using Fabry–Perot resonance condition for the nanocavity. For any desired filtering frequency the dimension of the nanocavity can be tailored. The numerical results are based on the two-dimensional finite difference time domain simulation under a perfectly matched layer absorbing boundary condition. The analytical and simulation results indicate that the proposed structure can be utilized for filtering and splitting applications.
基金Project supported by the National Key Research and Development Program of China(Grant No.2018YFA0306200)the National Natural Science Foundation of China(Grant No.11974119)Guangdong Provincial Innovative and Entrepreneurial Research Team Program,China。
文摘The strongly coupled system composed of atoms,molecules,molecule aggregates,and semiconductor quantum dots embedded within an optical microcavity/nanocavity with high quality factor and/or low modal volume has become an excellent platform to study cavity quantum electrodynamics(CQED),where a prominent quantum effect called Rabi splitting can occur due to strong interaction of cavity-mode single-photon with the two-level atomic states.In this paper,we build a new quantum model that can describe the optical response of the strongly-coupled system under the action of an external probing light and the spectral lineshape.We take the Hamiltonian for the strongly-coupled photon-atom system as the unperturbed Hamiltonian H_(0)and the interaction Hamiltonian of the probe light upon the coupled-system quantum states as the perturbed Hamiltonian V.The theory yields a double Lorentzian lineshape for the permittivity function,which agrees well with experimental observation of Rabi splitting in terms of spectral splitting.This quantum theory will pave the way to construct a complete understanding for the microscopic strongly-coupled system that will become an important element for quantum information processing,nano-optical integrated circuits,and polariton chemistry.
基金Project supported by the National Key Basic Research Special Foundation of China(Grant Nos.2012CB921501 and 2013CB632703)the National Natural Science Foundation of China(Grant Nos.11274160,91221206,and 51271092)
文摘Herein,we propose a high-quality(Q) factor hybrid plasmonic nanocavity based on distributed Bragg reflectors(DBRs) with low propagation loss and extremely strong mode confinement.This hybrid plasmonic nanocavity is composed of a high-index cylindrical nanowire separated from a metal surface possessing shallow DBRs gratings by a sufficiently thin low-index dielectric layer.The hybrid plasmonic nanocavity possesses advantages such as a high Purcell factor(Fp) of up to nearly 20000 and a gain threshold approaching 266 cm^(-1)at 1550 nm,promising a greater potential in deep sub-wavelength lasing applications.
基金Supported by the National Key Basic Research Special Fund/CNKBRSF of China under Grant Nos 2012CB933501,2016YFA0301102,2016YFB0401804 and 2016YFB0402203the National Natural Science Foundation of China under Grant Nos61535013,61321063 and 61137003+1 种基金the Strategic Priority Research Program of the Chinese Academy of Sciences under Grant Nos XDB24010100,XDB24010200,XDB24020100 and XDB24030100the One Hundred Person Project of the Chinese Academy of Sciences
文摘The single and coupled photonic crystal nanocavity lasers are fabricated in the InGaAsP material system and their static and dynamic features are compared. The coupled-cavity lasers show a larger lasing e^ciency and generate an output power higher than the single-cavity lasers, results that are consistent with the theoretical results obtained by rate equations. In dynamic regime, the single-cavity lasers produce pulses as short as 113 ps, while the coupled-cavity lasers show a significantly longer lasing duration. These results indicate that the photonic crystal laser is a promising candidate for the light source in high-speed photonic integrated circuit.
基金We are grateful to AgriLife Research of Texas A&M for the provided financial support.We also acknowledge Governor’s University Research Initiative(GURI)grant program of Texas A&M University,GURI Grant Agreement No.12-2016,M1700437R.W.acknowledges the financial support from the State Key Laboratory of Analytical Chemistry for Life Science,Nanjing University(No.SKLACLS2215).
文摘Localized surface plasmon resonances(LSPR)generated in a particle-film nanocavity enhance electric fields within a nanoscale volume.LSPR can also decay into hot carriers,highly energetic species that catalyze photocatalytic reactions in molecular analytes located in close proximity to metal surfaces.In this study,we examined the intensity of the electric field(near-field)and photocatalytic properties of plasmonic nanocavities formed by single nanoparticles(SNP)on single nanoplates(SNL).Using 4-nitrobenzenethiol(4-NBT)as a molecular reporter,we determined the near-field responses,as well as measured rates of 4-NBT dimerization into 4,4-dimercaptoazobenzene(DMAB)in the gold(Au)SNP on AuSNL nanocavity(Au-Au),as well as in AuSNP on AgSNL(Au-Ag),AgSNP on AuSNL(Ag-Au),and AgSNP on AgSNL(Ag-Ag)nanocavities using 532,660,and 785 nm excitations.We observed the strongest near-field signals of 4-NBT at 660 nm in all examined plasmonic systems that is found to be substantially red-shifted relative to the LSPR of the corresponding nanoparticles.We also found that rates of DMAB formation were significantly greater in heterometal nanocavities(Au-Ag and Ag-Au)compared to their monometallic counterparts(Au-Au and Ag-Ag).These results point to drastic differences in plasmonic and photocatalytic properties of mono and bimetallic nanostructures.
基金This work is supported by the National Key R&D Program of China(2018YFA0704401)the Beijing Natural Science Foundation(Z180011)+1 种基金the National Natural Science Foundation of China(12225402,91950115,11774014,61521004 and 62175003)the Tencent Foundation.
文摘Simultaneous localization of light to extreme spatial and spectral scales is of high importance for testing fundamental physics and various applications.However,there is a longstanding trade-off between localizing a light field in space and in frequency.Here we discover a new class of twisted lattice nanocavities based on mode locking in momentum space.The twisted lattice nanocavity hosts a strongly localized light field in a 0.048𝜆3 mode volume with a quality factor exceeding 2.9×1011(∼250𝜇s photon lifetime),which presents a record high figure of merit of light localization among all reported optical cavities.Based on the discovery,we have demonstrated silicon-based twisted lattice nanocavities with quality factor over 1 million.Our result provides a powerful platform to study light-matter interaction in extreme conditions for tests of fundamental physics and applications in nanolasing,ultrasensing,nonlinear optics,optomechanics and quantum-optical devices.
基金Key Research Program of Frontier Sciences,Chinese Academy of Sciences(QYZDJ-SSW-JSC002)National Natural Science Foundation of China(NSFC)(61527823,61875188)
文摘Whispering-gallery-mode(WGM) hexagonal optical micro-/nanocavities can be utilized as high-quality(Q) resonators for realizing compact-size low-threshold lasers. In this paper, the progress in WGM hexagonal micro-/nanocavity lasers is reviewed comprehensively. High-Q WGMs in hexagonal cavities are divided into two kinds of resonances propagating along hexagonal and triangular periodic orbits, with distinct mode characteristics according to theoretical analyses and numerical simulations;however, WGMs in a wavelength-scale nanocavity cannot be well described by the ray model. Hexagonal micro-/nanocavity lasers can be constructed by both bottom-up and top-down processes, leading to a diversity of these lasers. The ZnO-or nitride-based semiconductor material generally has a wurtzite crystal structure and typically presents a natural hexagonal cross section. Bottom-up growth guarantees smooth surface faceting and hence reduces the scattering loss effectively.Laser emissions have been successfully demonstrated in hexagonal micro-/nanocavities synthesized with various materials and structures. Furthermore, slight deformation can be easily introduced and precisely controlled in top-down fabrication, which allows lasing-mode manipulation. WGM lasing with excellent singletransverse-mode property was realized in waveguide-coupled ideal and deformed hexagonal microcavity lasers.
基金National Natural Science Foundation of China (NSFC) (11647001,11804004)Natural Science Foundation of Anhui Province (1708085QA11)
文摘The coherent light-matter interaction has drawn an enormous amount of attention for its fundamental importance in the cavity quantum-electrodynamics (C-QED) field and great potential in quantum information applications. Here, we design a hybrid C-QED system consisting of a quantum dot (QD) driven by two-tone fields implanted in a photonic crystal (PhC) cavity coupled to an auxiliary cavity with a single-mode waveguide and investigate the hybrid system operating in the weak, intermediate, and strong coupling regimes of the light-matter interaction via comparing the QD-photon interaction with the dipole decay rate and the cavity field decay rate.The results indicate that the auxiliary cavity plays a key role in the hybrid system, which affords a quantum channel to influence the absorption of the probe field. By controlling the coupling strength between the auxiliary cavity and the PhC cavity, the phenomenon of the Mollow triplet can appear in the intermediate coupling regime,and even in the weak coupling regime. We further study the strong coupling interaction manifested by vacuum Rabi splitting in the absorption with manipulating the cavity-cavity coupling under different parameter regimes.This study provides a promising platform for understanding the dynamics of QD-C-QED systems and paving the way toward on-chip QD-based nanophotonic devices.
基金supported by the National Natural Science Foundation of China (Grants 11272249 and 11525209)
文摘Surface energy plays an important role in the mechanical performance of nanomaterials; however, determining the surface energy density of curved surfaces remains a challenge. In this paper, we conduct atomic simulations to calculate the surface energy density of spherical surfaces in various crystalline metals. It is found that the average surface energy density of spherical surfaces remains almost constant once its radius exceeds 5 nm. Then, using a geometrical analysis and the scaling law, we develop an analytical approach to estimate the surface energy density of spherical surfaces through that of planar surfaces. The theoretical prediction agrees well with the direct atomic simulations, and thus provides a simple and general method to calculate the surface energy density in crystals.
基金Project supported by the National Natural Science Foundation of China (Grant Nos. 10674038 and 10604042)the National Basic Research Program of China (Grant No. 2006CB302901)
文摘The enhancement characteristics of the local field in the surface plasmon nanocavities are investigated numerically. The cavity is constructed by placing a defect structure in the thickness-modulated metal-insulator-metal waveguide Bragg gratings. The characteristic impedance based transfer matrix method is used to calculate the transmission spectra and the resonant wavelength of the cavities with various geometric parameters. The finite-difference time- domain method is used to obtain the field pattern of the resonant mode and validate the results of the transfer matrix method. The calculation and simulation results reveal the existence of resonant wavelength shift and intensity variation with structural parameters, such as the modulation period of the gratings, the length and the width of the defect structure. Both numerical analysis and theoretical interpretation on these phenomena are given in details.
基金Project supported by the Natural Science Foundation of Shandong Province,China(Grant No.ZR2015AM024)the Doctoral Research Started Funding of Qufu Normal University,China(Grant No.BSQD20130152)
文摘With nanovoids buried in Co films, resonant structures were observed in spectra of polar magneto-optical Kerr effect(MOKE), where both a narrow bandwidth and high intensity were acquired. Through changing the thickness of Co films and the lattice of voids, different optical modes were introduced. For a very shallow array of voids, the resonant MOKE was induced by Ag plasma edge resonance, for deeper ones, hybrid plasma modes, such as void plasmons in the voids, surface lattice plasmons between the voids, and the co-action of them, etc. resulted in resonant MOKE. We found that resonant MOKE resulted from the void plasmons resonance which possesses the narrowest bandwidth for the lowest absorption of voids. The simulated electromagnetic field(EF) distribution consolidated different effects of these three optical modes on resonant MOKE modulation. Such resonant polar MOKE possesses high sensitivity, which might pave the way to on-chip MO devices.
基金the financial supports from the National Natural Science Foundation of China(21988101,21890753 and 52142501)the Key Research Program of Frontier Sciences of the Chinese Academy of Sciences(QYZDB-SSWJSC020)+2 种基金the Strategic Priority Research Program of Chinese Academy of Sciences(XDB36030200)the National Key Research and Development Program of China(2018YFA0703400)the BP Alternative Energy International Limited。
文摘Developing a convenient method to endow bulk Cu-based electrode with high activity of electrocatalytic CO_(2)reduction reaction(CO_(2)RR)to multicarbon(C_(2+))products is desirable but challenging.Herein,for the first time,we report that mechanical polishing induces highly reactive Cu sites for selective C-C coupling in CO_(2)RR.We find that mechanical polishing could endow Cu foil with abundant nanocavity surface structure,which efficiently confines the carbonaceous intermediates to enhance the probability of C-C coupling reaction.By confining the carbonaceous intermediates with Cu nanocavity,the as-prepared electrode delivers a Faradaic efficiency toward C_(2+)products of 65.7%at-1.3 V vs.RHE,which is enhanced up to 1.7 folds compared with that of commercial Cu foil.This work provides a new method to enable Cu foil with high activity of CO_(2)RR to C_(2+)products.
基金supported by the National Basic Research Program of China (Grant No. 2011CBA00608)the China Postdoctoral Science Foundationthe National Quality Inspection Service Industry Scientific Research of China (Grant No. 201010007)
文摘A horizontally slotted photonic crystal nanobeam cavity with an embedded active nanopillar structure is proposed for ultrafast direct modulation. By designing the thicknesses of both the nanobeam and the horizontal slot layer, the quality factor (Q factor) and the mode volume (Vn) of the proposed cavity can be engineered independently. As a result, the spontaneous emission (SpE) rate is enhanced with a small Vn of 2.4 while the SpE rate and the cavity photon lifetime have an optimal Q factor of ~ 1000. In our simulation, the modulation bandwidth could be enhanced up to 170 GHz with different emission linewidths nf the~ netiv~ nnnnnillnr
基金supported by the National Natural Science Foundation of China(Nos.52072182 and 51872145)Natural Science Foundation of Jiangsu Province(No.BK20211278)+2 种基金the China Postdoctoral Science Foundation(Nos.2019M650120 and 2020M671554)the National Synergetic Innovation Center for Advanced Materials(SICAM)Postgraduate Research Practice Innovation Program of Jiangsu Province(No.KYCX22_0977).
文摘Reducing kinetic energy barriers and developing accessible active sites are critical to deliver high hydrogen evolution reaction(HER)efficiency.In this paper,we synthesized defect-modulated and heteroatom(boron)-functionalized three-dimensional(3D)bowl-shaped Ti_(3−x)C_(2)T_(y)MXene(B-TCT)nanocavities coupled with the vertical growth of MoSe_(2)nanoflakes.The B-TCT@MoSe_(2)nanohybrids catalyst delivers the overpotentials of 49.9,52.7,and 67.8 mV to reach a HER current density of 10 mA·cm^(−2)under acidic,alkaline,and neutral conditions,respectively.Such outstanding HER activity is predominantly attributed to the heteroatom functionalization,self-adapting Ti vacancy(VTi)defect modulation,and spatial configuration design in the 3D B-TCT nanocavity,which synergistically regulate the electronic structure,activate the basal plane/edge unsaturated sites,and reduce the reaction energy barrier.Experimental and theoretical calculations demonstrate that strong heterogeneous interfacial bonding interactions between B-TCT and MoSe_(2)can dramatically reduce the free energy of hydrogen adsorption and facilitate efficient interfacial charge migration,thus essentially improving the HER kinetics.We used this 3D porous nanohybrid system assembled by defectrich lamellar structures to elucidate the advantageous synergistic effects of multiple mechanisms among defect structure,heteroatom functionalization,and interfacial coupling,which provided important insights for the development of efficient hybridtype catalysts.
基金This work was supported by the National Key Research and Development Program of China(No.2021YFA1400700)the National Natural Science Foundation of China(Nos.61888102,62204259,62174179,92265110,11974386,12074420,U21A20140 and 61905274)+4 种基金the Beijing Municipal Science&Technology Commission,Administrative Commission of Zhongguancun Science Park(No.Z211100004821009)the Strategic Priority Research Program of Chinese Academy of Sciences(CAS)(Nos.XDB33000000 and XDB28000000)the Key Research Program of Frontier Sciences of CAS(Nos.QYZDJ-SSWSLH042 and XDPB22)the Project for Young Scientists in Basic Research of CAS(No.YSBR021)This work was also supported by the Synergic Extreme Condition User Facility,China.
文摘Polarization-sensitive photodetectors based on two-dimensional(2D)materials have shown more attractive application prospects compared to traditional thin-film photodetectors due to their atomic thickness,tunable bandgap,high mobility and strong light-matter interactions.Among them,2D molybdenum disulfide(MoS_(2))has drawn numerous attentions in photodetection due to its wide spectral range,remarkable photoresponsivity and fast photo-switching rate.However,the isotropic crystal structure of MoS_(2)hampers its application in the polarization-sensitive detection,which is highly desired in military and civilian applications.In this paper,we demonstrated an integration of plasmonic nanocavity with monolayer MoS_(2)to achieve high photoresponsivity and polarization-sensitive photodetector.With the significant enhancement of electromagnetic field provided by the gap-surfaceplasmon(GSP),we achieved a significant photoluminescence(PL)enhancement of 24-fold.Relying on the enhanced light absorption by our plasmonic nanocavity,which generally facilitates photo-generation of electron-hole pairs in MoS_(2),we achieved a high photoresponsivity of 1.88 A/W and degree of linear polarization(DOLP)of 0.8 at the excitation wavelength of 633 nm.Our work provides a feasible and universal solution to realize polarization-sensitive photodetector of MoS_(2)for high-performance and polarization-sensitive photodetectors.
基金supported by the National Natural Science Foundation of China(grant No.21776217 and 21978214).
文摘Mixed matrix membranes(MMMs)with the performance between the matrix and the filler is a promising strategy for membranes with excellent gas permeability-selectivity.In this study,the hollow polydimethylsiloxane nanoparticles were synthesized and then incorporated with the poly(oxide ethylene)monomer and tri-functional cross-linker to form mixed matrix membranes by in situ poly-merization.The hollow nanoparticles formed the independent closed nanocavities in membranes,which enhanced the gas permeability contributed by both the improved diffusivity and solubility.At high loading,the hollow polydimethylsiloxane nanoparticle was converted into the continuous phase with the cross-linked poly(oxide ethylene)as the dispersed phase.Gases preferred to permeate through the connected cluster of hollow polydimethylsiloxane nanoparticles,finally leading to ultrahigh gas per-meabilities far going beyond the instinct values of polydimethylsiloxane and the cross-linked poly(oxide ethylene).The optimized membrane with 34 wt%hollow nanoparticles loadings exhibited ultrahigh permeabilities with the values of 44186 Barrer for CO_(2) and 11506 Barrer for O_(2),accompanied with a CO_(2)/N_(2) selectivity of 9.9 and an O_(2)/N_(2) selectivity of 2.6,which exceeded the 2008 Robeson upper bound for O_(2)/N_(2) and located at the 2008 Robeson upper bound for CO_(2)/N_(2).
基金supported by the National Key Research and Development Program of China(No.2019YFA0705400)the National Natural Science Foundation of China(Nos.21925404,22002128,22104135,62004095,and 22021001)Zhejiang Provincial Natural Science Foundation of China(No.LY23B050003).
文摘Monolayer graphene has attracted enormous attention owing to its unique electronic and optical properties.However,achieving an effective approach without applying electrical bias for manipulating the charge transfer based on graphene is elusive to date.Herein,we realized the manipulation of excitons’transition from emitter to the graphene surface with plasmonic engineering nanostructures and firstly obtained large enhancements for photon emission on the graphene surface.The localized plasmons generated from the plasmonic nanostructures of shell-isolated nanoparticle coupling to ultra-flat Au substrate would dictate a consistent junction geometry while enhancing the optical field and dominating the electron transition pathways,which may cause obvious perturbations for molecular radiation behaviors.Additionally,the three-dimensional finite-difference time-domain and time-dependent density functional theory were also carried out to simulate the distributions of electromagnetic field and energy levels of hybrid nanostructure respectively and the results agreed well with the experimental data.Therefore,this work paves a novel approach for tunning graphene charge/energy transfer processes,which may hold great potential for applications in photonic devices based on graphene.