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
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
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
High-index dielectric nanoparticles supporting strong Mie resonances,such as silicon(Si)nanoparticles,provide a platform for manipulating optical fields at the subwavelength scale.However,in general,the quality factor...High-index dielectric nanoparticles supporting strong Mie resonances,such as silicon(Si)nanoparticles,provide a platform for manipulating optical fields at the subwavelength scale.However,in general,the quality factors of Mie resonances supported by an isolated nanoparticle are not sufficient for realizing strong light-matter interaction.Here,we propose the use of dielectric-metal hybrid nanocavities composed of Si nanoparticles and silicon nitride/silver(Si_(3)N_(4)∕Ag)heterostructures to improve light-matter interaction.First,we demonstrate that the nonlinear optical absorption of the Si nanoparticle in a Si∕Si_(3)N_(4)∕Ag hybrid nanocavity can be greatly enhanced at the magnetic dipole resonance.The Si∕Si_(3)N_(4)∕Ag nanocavity exhibits luminescence burst at substantially lower excitation energy(~20.5 pJ)compared to a Si nanoparticle placed on a silica substrate(~51.3 pJ).The luminescence intensity is also enhanced by an order of magnitude.Second,we show that strong exciton-photon coupling can be realized when a tungsten disulfide(WS2)monolayer is inserted into a Si∕Si_(3)N_(4)∕Ag nanocavity.When such a system is excited by using s-polarized light,the optical resonance supported by the nanocavity can be continuously tuned to sweep across the two exciton resonances of the WS_(2)monolayer by simply varying the incident angle.As a result,Rabi splitting energies as large as~146.4 meV and~110 meV are observed at the A-and B-exciton resonances of the WS_(2)monolayer,satisfying the criterion for strong exciton-photon coupling.The proposed nanocavities provide,to our knowledge,a new platform for enhancing light-matter interaction in multiple scenarios and imply potential applications in constructing nanoscale photonic 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-/nanocav...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
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
In this paper, we presented switching dynamic investigations on an InP photonic-crystal （PhC） nanocavity structure using homodyne pump-probe measurements. The measurements were compared with simulations based on tem...In this paper, we presented switching dynamic investigations on an InP photonic-crystal （PhC） nanocavity structure using homodyne pump-probe measurements. The measurements were compared with simulations based on temporal nonlinear coupled mode theory and carrier rate equations for the dynamics of the carrier density governing the cavity properties. The results provide insight into the nonlinear optical processes that govern the dynamics of nanocavities.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
Energy transfer is ubiquitous in natural and artificial lightharvesting systems,and coherent energy transfer,a highly efficient energy transfer process,has been accepted to play a vital role in such systems.However,th...Energy transfer is ubiquitous in natural and artificial lightharvesting systems,and coherent energy transfer,a highly efficient energy transfer process,has been accepted to play a vital role in such systems.However,the energy oscillation of coherent energy transfer is exceedingly difficult to capture because of its evanescence due to the interaction with a thermal environment.Here a microscopic quantum model is used to study the time evolution of electrons triggered energy transfer between coherently coupled donoracceptor molecules in scanning tunneling microscope(STM).A series of topics in the plasmonic nanocavity(PNC)coupled donor-acceptor molecules system are discussed,including resonant and nonresonant coherent energy transfer,dephasing assisted energy transfer,PNC coupling strength dependent energy transfer,Fano resonance of coherently coupled donor-acceptor molecules,and polariton-mediated energy transfer.展开更多
We demonstrate that a moirésuperlattice nanocavity constructed in a photonic crystal slab promises strongly enhanced nonlinear optics,which is beneficial from the high-quality factor and high coupling efficiency ...We demonstrate that a moirésuperlattice nanocavity constructed in a photonic crystal slab promises strongly enhanced nonlinear optics,which is beneficial from the high-quality factor and high coupling efficiency of the flat-band mode with zero group velocity.From a silicon moirésuperlattice nanocavity integrated with few-layer gallium selenide(GaSe),the second-harmonic generation(SHG)of GaSe is enhanced by over 10,000 times,and the third-harmonic generation(THG)is enhanced by 8500 times.Our results suggest the moirésuperlattice nanocavity could be considered as a promising platform for developing high-efficiency nonlinear photonic devices.展开更多
Surface plays an important role in the physical and mechanical behavior of nanos- tructured materials and elements, however surface energy of curved solid surfaces has not been fully understood. In the present letter,...Surface plays an important role in the physical and mechanical behavior of nanos- tructured materials and elements, however surface energy of curved solid surfaces has not been fully understood. In the present letter, surface energy of spherical particles and cavities in FCC copper is calculated by embedded atom method. The numerical simulations reveal that the dis- tribution of atom energy is non-uniform on the curved surfaces. However, when the radius of spherical cavity or particle is larger than 4 nm, the average surface energy density keeps almost constant irrespective of its location and radius.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
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
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
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National Natural Science Foundation of China(12174123,12374347)Basic and Applied Basic Research Foundation of Guangdong Province(2022A1515010747)。
文摘High-index dielectric nanoparticles supporting strong Mie resonances,such as silicon(Si)nanoparticles,provide a platform for manipulating optical fields at the subwavelength scale.However,in general,the quality factors of Mie resonances supported by an isolated nanoparticle are not sufficient for realizing strong light-matter interaction.Here,we propose the use of dielectric-metal hybrid nanocavities composed of Si nanoparticles and silicon nitride/silver(Si_(3)N_(4)∕Ag)heterostructures to improve light-matter interaction.First,we demonstrate that the nonlinear optical absorption of the Si nanoparticle in a Si∕Si_(3)N_(4)∕Ag hybrid nanocavity can be greatly enhanced at the magnetic dipole resonance.The Si∕Si_(3)N_(4)∕Ag nanocavity exhibits luminescence burst at substantially lower excitation energy(~20.5 pJ)compared to a Si nanoparticle placed on a silica substrate(~51.3 pJ).The luminescence intensity is also enhanced by an order of magnitude.Second,we show that strong exciton-photon coupling can be realized when a tungsten disulfide(WS2)monolayer is inserted into a Si∕Si_(3)N_(4)∕Ag nanocavity.When such a system is excited by using s-polarized light,the optical resonance supported by the nanocavity can be continuously tuned to sweep across the two exciton resonances of the WS_(2)monolayer by simply varying the incident angle.As a result,Rabi splitting energies as large as~146.4 meV and~110 meV are observed at the A-and B-exciton resonances of the WS_(2)monolayer,satisfying the criterion for strong exciton-photon coupling.The proposed nanocavities provide,to our knowledge,a new platform for enhancing light-matter interaction in multiple scenarios and imply potential applications in constructing nanoscale photonic 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.
文摘In this paper, we presented switching dynamic investigations on an InP photonic-crystal （PhC） nanocavity structure using homodyne pump-probe measurements. The measurements were compared with simulations based on temporal nonlinear coupled mode theory and carrier rate equations for the dynamics of the carrier density governing the cavity properties. The results provide insight into the nonlinear optical processes that govern the dynamics of nanocavities.
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supported by the State Scholarship Fund organized by the China Scholarship Council(CSC).
文摘Energy transfer is ubiquitous in natural and artificial lightharvesting systems,and coherent energy transfer,a highly efficient energy transfer process,has been accepted to play a vital role in such systems.However,the energy oscillation of coherent energy transfer is exceedingly difficult to capture because of its evanescence due to the interaction with a thermal environment.Here a microscopic quantum model is used to study the time evolution of electrons triggered energy transfer between coherently coupled donoracceptor molecules in scanning tunneling microscope(STM).A series of topics in the plasmonic nanocavity(PNC)coupled donor-acceptor molecules system are discussed,including resonant and nonresonant coherent energy transfer,dephasing assisted energy transfer,PNC coupling strength dependent energy transfer,Fano resonance of coherently coupled donor-acceptor molecules,and polariton-mediated energy transfer.
基金National Key Research and Development Program of China(2022YFA1404800)National Natural Science Foundation of China(12374359,62375225,62305270,62205273,62104198)+2 种基金Xi'an Science and Technology Plan Project(2023JH-ZCGJ-0023)Shaanxi Fundamental Science Research Project for Mathematics and Physics(22JSY004,22JSQ039)Key R&D Program of Shaanxi Province(2023-JC-YB-502)。
文摘We demonstrate that a moirésuperlattice nanocavity constructed in a photonic crystal slab promises strongly enhanced nonlinear optics,which is beneficial from the high-quality factor and high coupling efficiency of the flat-band mode with zero group velocity.From a silicon moirésuperlattice nanocavity integrated with few-layer gallium selenide(GaSe),the second-harmonic generation(SHG)of GaSe is enhanced by over 10,000 times,and the third-harmonic generation(THG)is enhanced by 8500 times.Our results suggest the moirésuperlattice nanocavity could be considered as a promising platform for developing high-efficiency nonlinear photonic devices.
基金supported by the the NCET Program and the SRF for ROCS of the Ministry of Educationthe National Natural Science Foundation of China (No.11072186)
文摘Surface plays an important role in the physical and mechanical behavior of nanos- tructured materials and elements, however surface energy of curved solid surfaces has not been fully understood. In the present letter, surface energy of spherical particles and cavities in FCC copper is calculated by embedded atom method. The numerical simulations reveal that the dis- tribution of atom energy is non-uniform on the curved surfaces. However, when the radius of spherical cavity or particle is larger than 4 nm, the average surface energy density keeps almost constant irrespective of its location and radius.
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.
