Localized surface plasmon resonance(LSPR) has caused extensive concern and achieved widespread applications in optoelectronics. However, the weak coupling of plasmons and excitons in a nanometal/semiconductor system r...Localized surface plasmon resonance(LSPR) has caused extensive concern and achieved widespread applications in optoelectronics. However, the weak coupling of plasmons and excitons in a nanometal/semiconductor system remains to be investigated via energy transfer. Herein, bandgap tunable perovskite films were synthesized to adjust the emission peaks,for further coupling with stable localized surface plasmons from gold nanoparticles. The degree of mismatch, using steadystate and transient photoluminescence(PL), was investigated systematically in two different cases of gold nanoparticles that were in direct contacting and insulated. The results demonstrated the process of tuning emission coupled to LSPR via wavelength-dependent photoluminescence intensity in the samples with an insulating spacer. In the direct contact case,the decreased radiative decay rate involves rapid plasmon resonance energy transfer to the perovskite semiconductor and non-radiative energy transfer to metal nanoparticles in the near-field range.展开更多
The reflected group delay from a multilayer structure comprising a one-dimensional photonic crystal coated with a bulk Dirac semimetal(BDS)separated by a spacer layer is investigated theoretically.It is shown that the...The reflected group delay from a multilayer structure comprising a one-dimensional photonic crystal coated with a bulk Dirac semimetal(BDS)separated by a spacer layer is investigated theoretically.It is shown that the group delay of the reflected beam in this structure can be significantly negatively enhanced and switched from negative to positive.The enhanced group delay originates from the steep phase change caused by the excitation of the optical Tamm state at the interface between the BDS and spacer layer.Moreover,positive and negative group delays can be actively tuned through the Fermi energy and the relaxation time of the BDS.We believe that this enhanced and tunable delay scheme has important research significance for the fabrication of optical delay devices.展开更多
We propose a novel scheme to guide neutral cold atoms in a nanoscale region based on surface plasmons (SPs) of one pair and two pairs of tips of metallic wedges with locally enhanced light intensity and sub-optical ...We propose a novel scheme to guide neutral cold atoms in a nanoscale region based on surface plasmons (SPs) of one pair and two pairs of tips of metallic wedges with locally enhanced light intensity and sub-optical wavelength resolution. We analyze the near-field intensity distribution of the tip of the metallic wedge by the FDTD method, and study the total intensity as well as the total potential of optical potentials and van der Waals potentials for 87 Rb atoms in the light field of one pair and two pairs of tips of metallic wedges. It shows that the total potentials of one pair and two pairs of tips of metallic wedges can generate a gravito-optical trap and a dark closed trap for nanoscale guiding of neutral cold atoms. Guided atoms can be cooled with efficient intensity-gradient Sisyphus cooling by blue-detuned light field. This provides an important step towards the generation of hybrid systems consisting of isolated atoms and solid devices.展开更多
A current-driven source of long-range surface plasmons(LRSPs)on a duplex metal nanolayer is reported.Electrical excitation of LRSPs was experimentally observed in a planar structure,where an organic light-emitting fil...A current-driven source of long-range surface plasmons(LRSPs)on a duplex metal nanolayer is reported.Electrical excitation of LRSPs was experimentally observed in a planar structure,where an organic light-emitting film was sandwiched between two metal nanolayers that served as electrodes.To achieve the LRSP propagation in these metal nanolayers at the interface with air,the light-emitting structure was bordered by a one-dimensional photonic crystal(PC)on the other side.The dispersion of the light emitted by such a hybrid PC/organic-light-emitting-diode structure(PC/OLED)comprising two thin metal electrodes was obtained,with a clearly identified LRSP resonance peak.展开更多
The excitation of surface plasmons (SPs) with a strip grating at the boundary of an unmagnetized overdense plasma has been investigated theoretically and experimentally. An incident electromagnetic radiation was p-p...The excitation of surface plasmons (SPs) with a strip grating at the boundary of an unmagnetized overdense plasma has been investigated theoretically and experimentally. An incident electromagnetic radiation was p-polarized at the frequency of 5 GHz. Experiments showed that when the plasma density was four times higher than the critical density with the grating present, and the SPs could be excited at the boundary of the overdense plasma. Contribution of the glass layer in the formation of the SP dispersion relation was examined. When the incident electromagnetic radiation was coupled into SPs the coupling order with the effective permittivity was simulated qualitatively. We find that the existence of SPs at the boundary of overdense plasma indicates that the reflection coefficient of the incident electromagnetic radiation reaches its minimum and even becomes total absorption. In this work the plasma density was diagnosed by a Langmuir double probe.展开更多
Using propagating surface plasmons (SPs) on a silver nanowire (NW), we demonstrate that a focused laser light at the end of the silver NW can excite a single quantum dot (QD) microns away from the excitation spo...Using propagating surface plasmons (SPs) on a silver nanowire (NW), we demonstrate that a focused laser light at the end of the silver NW can excite a single quantum dot (QD) microns away from the excitation spot. The QD-NW interaction allows the excited QD convert part of its energy into propagating SPs, which then can be detected at remote sites. Simultaneous multi-QD remote excitation and remote detection can also be realized. Furthermore, the tight confinement of the propagating SPs around the NW surface enables the selective excitation of QDs very close in space, which cannot be realized under the conventional excitation condition. This remote excitation and remote detection approach may find applications in optical imaging and the sensing of chemical and biological systems.展开更多
On the assumption that the resonant surface plasmons on a spherical nanoparticle are formed by standing waves of two counter-propagating surface plasmon waves along the surface, by using Mie theory simulation, we find...On the assumption that the resonant surface plasmons on a spherical nanoparticle are formed by standing waves of two counter-propagating surface plasmon waves along the surface, by using Mie theory simulation, we find that the dispersions of surface plasmon resonant modes supported by silver nanospheres match with those of the surface plasmons on a semiinfinite medium-silver interface very well. This suggests that the resonant surface plasmons of a metal nanosphere can be treated as a propagating surface plasmon wave.展开更多
The collective charge density excitations in a free-standing nanorod with a two-dimensional parabolic quantum well are investigated within the framework of Bohm-Pine's random-phase approximation in the two-subband mo...The collective charge density excitations in a free-standing nanorod with a two-dimensional parabolic quantum well are investigated within the framework of Bohm-Pine's random-phase approximation in the two-subband model.The new simplified analytical expressions of the Coulomb interaction matrix elements and dielectric functions are derived and numerically discussed.In addition,the electron density and temperature dependences of dispersion features are also investigated.We find that in the two-dimensional parabolic quantum well,the intrasubband upper branch is coupled with the intersubband mode,which is quite different from other quasi-one-dimensional systems like a cylindrical quantum wire with an infinite rectangular potential.In addition,we also find that higher temperature results in the intersubband mode(with an energy of 12 meV(~ 3 THz)) becoming totally damped,which agrees well with the experimental results of Raman scattering in the literature.These interesting properties may provide useful references to the design of free-standing nanorod based devices.展开更多
We conduct in-situ near-field imaging of propagating and localized plasmons(cavity and dipole modes) in graphene nano-resonator. Compared with propagating graphene plasmons, the localized modes show twofold near-fie...We conduct in-situ near-field imaging of propagating and localized plasmons(cavity and dipole modes) in graphene nano-resonator. Compared with propagating graphene plasmons, the localized modes show twofold near-field amplitude and high volume confining ability(- 10^6). The cavity resonance and dipole mode of graphene plasmons can be effectively controlled through optical method. Furthermore, our numerical simulation shows quantitative agreement with experimental measurements. The results provide insights into the nature of localized graphene plasmons and demonstrate a new way to study the localization of polaritons in Van der Waals materials.展开更多
We propose an improved design and numerical study of an optimized tunable plasmonics artificial material resonator in the terahertz regime. We demonstrate that tunability can be realized with a transmission intensity ...We propose an improved design and numerical study of an optimized tunable plasmonics artificial material resonator in the terahertz regime. We demonstrate that tunability can be realized with a transmission intensity as much as - 61% in the lower frequency resonance, which is implemented through the effect of photoconductive switching under photoexcitation.In the higher frequency resonance, we show that spoof surface plasmons along the interface of metal/dielectric provide new types of electromagnetic resonances. Our approach opens up possibilities for the interface of metamaterial and plasmonics to be applied to optically tunable THz switching.展开更多
By using a microscopic quantum model,we study theoretically different roles of nanocavity plasmons in scanning tunneling microscope(STM)induced light emission upon selective initial excitation of molecules or plasmons...By using a microscopic quantum model,we study theoretically different roles of nanocavity plasmons in scanning tunneling microscope(STM)induced light emission upon selective initial excitation of molecules or plasmons.The time evolution and spectroscopic properties of the emission from the coupled plasmon-molecule system in each case are studied using time-dependent quantum mater equations.When the STM tip is placed on the molecule to ensure direct carrier injection induced molecular excitation,the major role of the plasmons is to enhance the molecular emission via increasing its radiative decay rate,resulting in sharp molecule-specic emission peaks.On the other hand,when the STM tip is located in close proximity to the edge of the molecule but without direct carrier injection into the molecule,the role of the plasmon-molecule coupling is to cause destructive interferences between the two quantum objects,leading to the occurrence of Fano dips around the energy of the molecular exciton in the plasmonic emission spectra.展开更多
Polarization dependence of the coupling of excitation light to surface plasmon polaritons (SPPs) was investigated in a Ag nanoparticle-nanowire waveguide system (a Ag nanoparticle attached to a Ag nanowire). It wa...Polarization dependence of the coupling of excitation light to surface plasmon polaritons (SPPs) was investigated in a Ag nanoparticle-nanowire waveguide system (a Ag nanoparticle attached to a Ag nanowire). It was found that under the illumination of excitation light on the nanoparticle-nanowire junction, the coupling efficiency of light to SPPs depends on the polarization of the excitation light. Theoretical simulations revealed that it is the local near-field coupling between the nanoparticle and the nanowire that enhances the incident light to excite the nanowire SPPs. Because the shapes of the Ag nanoparticles differ, the local field intensity, and thus the excitement of the nanowire SPPs, vary with the polarization of the excitation light.展开更多
In this paper, we demonstrate a spin-controlled directional launching of surface plasmons at the subwavelength scale.Based on the principle of optical spin's effect for the geometric phase of light, the nanostructure...In this paper, we demonstrate a spin-controlled directional launching of surface plasmons at the subwavelength scale.Based on the principle of optical spin's effect for the geometric phase of light, the nanostructures were designed. The inclination of the structures decides the spin-related geometric phase and their relative positions decide the distance-related phase. Hence, the propagation direction of the generated surface plasmon polaritons(SPPs) can be controlled by the spin of photons. Numerical simulations by the finite difference time domain(FDTD) method have verified our theoretical prediction. Our structure is fabricated on the Au film by using a focused ion beam etching technique. The total size of the surface plasmon polariton(SPP) launcher is 320 nm by 180 nm. The observation of the SPP launching by using scanning near-field optical microscopy is in agreement with our theory and simulations. This result may provide a new way of spin-controlled directional launching of SPP.展开更多
Au/GaAs/Au plasmonic cavities with a periodic hole array perforated in the top Au layer are studied.Propagating surface plasmons(PSPs)and localized surface plasmons(LSPs)associated with the rectangle hole shapes are f...Au/GaAs/Au plasmonic cavities with a periodic hole array perforated in the top Au layer are studied.Propagating surface plasmons(PSPs)and localized surface plasmons(LSPs)associated with the rectangle hole shapes are found to interact and highly hybridize in the cavity structure,which eventually determines the resonance properties of the cavities.An anticrossing of resonance frequencies in the reflection spectra is observed when the frequency of PSPs approaches that of LSPs,demonstrating the strong coupling between SPPs and LSPs in the tri-layer plasmonic cavities.This work may provide hints to the plasmonic cavity design for light-harvesting optoelectronic applications.展开更多
This paper analytically investigates the nonlinear behaviour of transverse plasraons in pair plasmas on the basis of the nonlinear governing equations obtained from Vlasov-Maxwell equations. It shows that high frequen...This paper analytically investigates the nonlinear behaviour of transverse plasraons in pair plasmas on the basis of the nonlinear governing equations obtained from Vlasov-Maxwell equations. It shows that high frequency transverse plasmons are modulationally unstable with respect to the uniform state of the pair plasma. Such an instability would cause wave field collapse into a localized region. During the collapse process, ponderomotive expulsion is greatly enhanced for the increase of wave field strength, leading to the formation of localized density cavitons which are significant for the future experimental research in the interaction between high frequency electromagnetic waves and pair plasmas.展开更多
We study the plasmonic properties of hybrid nanostructures consisting of double vacancy defected graphene(DVDGr)and metallic nanoarrays using the time-dependent density functional theory. It is found that DVDGr with p...We study the plasmonic properties of hybrid nanostructures consisting of double vacancy defected graphene(DVDGr)and metallic nanoarrays using the time-dependent density functional theory. It is found that DVDGr with pure and mixed noble/transition-metal nanoarrays can produce a stronger light absorption due to the coherent resonance of plasmons than graphene nanostructures. Comparing with the mixed Au/Pd nanoarrays, pure Au nanoarrays have stronger plasmonic enhancement. Furthermore, harmonics from the hybrid nanostructures exposed to the combination of lasers ranged from ultraviolet to infrared and a controlling pulse are investigated theoretically. The harmonic plateau can be broadened significantly and the energy of harmonic spectra is dramatically extended by the controlling pulse. Thus, it is possible to tune the width and intensity of harmonic spectrum to achieve broadband absorption of radiation. The methodology described here not only improves the understanding of the surface plasmon effect used in a DVDGr-metal optoelectronic device but also may be applicable to different optical technologies.展开更多
We present a modified method to solve the surface plasmons (SPs) of semi-infinite metal/dielectric superlattices and predicted new SP modes in physics. We find that four dispersion-equation sets and all possible SP ...We present a modified method to solve the surface plasmons (SPs) of semi-infinite metal/dielectric superlattices and predicted new SP modes in physics. We find that four dispersion-equation sets and all possible SP modes are determined by them. Our analysis and numerical calculations indicate that besides the SP mode obtained in the original theory, the other two SP modes are predicted, which have either a positive group velocity or a negative group velocity. We also point out the possible defect in the previous theoretical method in accordance to the linear algebra principle.展开更多
The longitudinal plasmons are the electrostatic collective excitations of the solid electron gas. In this paper, the dispersion relations of these plasmons for one-, two- and threedimensional electron gas are compactl...The longitudinal plasmons are the electrostatic collective excitations of the solid electron gas. In this paper, the dispersion relations of these plasmons for one-, two- and threedimensional electron gas are compactly derived in two approaches with uniform disturbed Coulomb potentials. The first approach is adopted usually in solid state theory that is the so-called random phase approximation (RPA) with the Lindhard dielectric function in the long-wavelength and high-frequency limits. The second method is a typical plasma fluid description that includes the electron fluid equations with the adiabatic process in the jellium model. The disturbed electrostatic (Coulomb) potential produced by the oscillation of electron density is dimensionally dependent and derived from the Poisson equation in Appendix B.展开更多
In this paper we investigate the influence of the next-nearest-neighbor coupling on the spectrum of plasmon excitations in graphene. The nearest-neighbor tight-binding model was previously considered to calculate the ...In this paper we investigate the influence of the next-nearest-neighbor coupling on the spectrum of plasmon excitations in graphene. The nearest-neighbor tight-binding model was previously considered to calculate the plasmon spectrum in graphene [1]. We extend these results to the next-nearest-neighbor tight-binding model. As in the calculation of the nearest-neighbor model, our approach is based on the numerical calculation of the dielectric function and the loss function. We compare the plasmon spectrum of the two models and discuss the differences in the dispersion.展开更多
Plasmonic resonators are widely used for the manipulation of light on subwavelength scales through the near-field electromagnetic wave produced by the collective oscillation of free electrons within metallic systems,w...Plasmonic resonators are widely used for the manipulation of light on subwavelength scales through the near-field electromagnetic wave produced by the collective oscillation of free electrons within metallic systems,well known as the surface plasmon(SP).The non-radiative decay of the surface plasmon can excite a plasmonic hot electron.This review article systematically describes the excitation progress and basic properities of SPs and plasmonic hot electrons according to recent publications.The extraction mechanism of plasmonic hot electrons via Schottky conjunction to an adjacent semiconductor is also illustrated.Also,a calculation model of hot electron density is given,where the efficiency of hot-electron excitation,transport and extraction is discussed.We believe that plasmonic hot electrons have a huge potential in the future development of optoelectronic systems and devices.展开更多
基金Project supported by the National Key R&D Program of China (Grant Nos. 2017YFA0700503 and 2018YFA0209101)the National Natural Science Foundation of China (Grant Nos. 61821002, 11734005, 62075041, and 61704024)。
文摘Localized surface plasmon resonance(LSPR) has caused extensive concern and achieved widespread applications in optoelectronics. However, the weak coupling of plasmons and excitons in a nanometal/semiconductor system remains to be investigated via energy transfer. Herein, bandgap tunable perovskite films were synthesized to adjust the emission peaks,for further coupling with stable localized surface plasmons from gold nanoparticles. The degree of mismatch, using steadystate and transient photoluminescence(PL), was investigated systematically in two different cases of gold nanoparticles that were in direct contacting and insulated. The results demonstrated the process of tuning emission coupled to LSPR via wavelength-dependent photoluminescence intensity in the samples with an insulating spacer. In the direct contact case,the decreased radiative decay rate involves rapid plasmon resonance energy transfer to the perovskite semiconductor and non-radiative energy transfer to metal nanoparticles in the near-field range.
基金Project supported by the Scientific research project of Zhejiang Provincial Department of Education(Grant No.Y202250547)the Scientific Research Project ofWenzhou University of Technology(Grant No.ky202205)the Hunan Provincial Natural Science Foundation of China(Grant No.2022JJ30394).
文摘The reflected group delay from a multilayer structure comprising a one-dimensional photonic crystal coated with a bulk Dirac semimetal(BDS)separated by a spacer layer is investigated theoretically.It is shown that the group delay of the reflected beam in this structure can be significantly negatively enhanced and switched from negative to positive.The enhanced group delay originates from the steep phase change caused by the excitation of the optical Tamm state at the interface between the BDS and spacer layer.Moreover,positive and negative group delays can be actively tuned through the Fermi energy and the relaxation time of the BDS.We believe that this enhanced and tunable delay scheme has important research significance for the fabrication of optical delay devices.
基金the National Basic Research Program of China(Grant No.2011CB013004)the National Natural Science Foundation of China(Grant No.50975128)+1 种基金the Natural Science Foundation of Jiangsu Province,China(Grant No.BK2011462)the Postdoctoral Science Foundation of China(Grant No.20100481093)
文摘We propose a novel scheme to guide neutral cold atoms in a nanoscale region based on surface plasmons (SPs) of one pair and two pairs of tips of metallic wedges with locally enhanced light intensity and sub-optical wavelength resolution. We analyze the near-field intensity distribution of the tip of the metallic wedge by the FDTD method, and study the total intensity as well as the total potential of optical potentials and van der Waals potentials for 87 Rb atoms in the light field of one pair and two pairs of tips of metallic wedges. It shows that the total potentials of one pair and two pairs of tips of metallic wedges can generate a gravito-optical trap and a dark closed trap for nanoscale guiding of neutral cold atoms. Guided atoms can be cooled with efficient intensity-gradient Sisyphus cooling by blue-detuned light field. This provides an important step towards the generation of hybrid systems consisting of isolated atoms and solid devices.
基金supported by the Swiss National Science Foundation (Grant 200021_162767)
文摘A current-driven source of long-range surface plasmons(LRSPs)on a duplex metal nanolayer is reported.Electrical excitation of LRSPs was experimentally observed in a planar structure,where an organic light-emitting film was sandwiched between two metal nanolayers that served as electrodes.To achieve the LRSP propagation in these metal nanolayers at the interface with air,the light-emitting structure was bordered by a one-dimensional photonic crystal(PC)on the other side.The dispersion of the light emitted by such a hybrid PC/organic-light-emitting-diode structure(PC/OLED)comprising two thin metal electrodes was obtained,with a clearly identified LRSP resonance peak.
文摘The excitation of surface plasmons (SPs) with a strip grating at the boundary of an unmagnetized overdense plasma has been investigated theoretically and experimentally. An incident electromagnetic radiation was p-polarized at the frequency of 5 GHz. Experiments showed that when the plasma density was four times higher than the critical density with the grating present, and the SPs could be excited at the boundary of the overdense plasma. Contribution of the glass layer in the formation of the SP dispersion relation was examined. When the incident electromagnetic radiation was coupled into SPs the coupling order with the effective permittivity was simulated qualitatively. We find that the existence of SPs at the boundary of overdense plasma indicates that the reflection coefficient of the incident electromagnetic radiation reaches its minimum and even becomes total absorption. In this work the plasma density was diagnosed by a Langmuir double probe.
基金supported by the National Natural Science Foundation of China(Grant Nos.11374012,11134013,11227407,and 61210017)the Ministry of Science and Technology of China(Grant No.2012YQ12006005)the Knowledge Innovation Project of Chinese Academy of Sciences(Grant No.KJCX2-EWW04)
文摘Using propagating surface plasmons (SPs) on a silver nanowire (NW), we demonstrate that a focused laser light at the end of the silver NW can excite a single quantum dot (QD) microns away from the excitation spot. The QD-NW interaction allows the excited QD convert part of its energy into propagating SPs, which then can be detected at remote sites. Simultaneous multi-QD remote excitation and remote detection can also be realized. Furthermore, the tight confinement of the propagating SPs around the NW surface enables the selective excitation of QDs very close in space, which cannot be realized under the conventional excitation condition. This remote excitation and remote detection approach may find applications in optical imaging and the sensing of chemical and biological systems.
基金supported by the National Natural Science Foundation of China(Grant No.11704058)the Fundamental Research Funds for the Central Universities,China(Grant No.DUT16RC(3)111)
文摘On the assumption that the resonant surface plasmons on a spherical nanoparticle are formed by standing waves of two counter-propagating surface plasmon waves along the surface, by using Mie theory simulation, we find that the dispersions of surface plasmon resonant modes supported by silver nanospheres match with those of the surface plasmons on a semiinfinite medium-silver interface very well. This suggests that the resonant surface plasmons of a metal nanosphere can be treated as a propagating surface plasmon wave.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.60976008,61006004,61076001,and 10979507)the National Basic Research Program of China(Grant No.A000091109-05)the National High Technology Research and Development Program of China(Grant No.2011AA03A101)
文摘The collective charge density excitations in a free-standing nanorod with a two-dimensional parabolic quantum well are investigated within the framework of Bohm-Pine's random-phase approximation in the two-subband model.The new simplified analytical expressions of the Coulomb interaction matrix elements and dielectric functions are derived and numerically discussed.In addition,the electron density and temperature dependences of dispersion features are also investigated.We find that in the two-dimensional parabolic quantum well,the intrasubband upper branch is coupled with the intersubband mode,which is quite different from other quasi-one-dimensional systems like a cylindrical quantum wire with an infinite rectangular potential.In addition,we also find that higher temperature results in the intersubband mode(with an energy of 12 meV(~ 3 THz)) becoming totally damped,which agrees well with the experimental results of Raman scattering in the literature.These interesting properties may provide useful references to the design of free-standing nanorod based devices.
基金Project supported by the National Key Research and Development Program of China(Grant No.2016YFA0203500)the National Natural Science Foundation of China(Grant No.11474350)+1 种基金the State Key Laboratory of Optoelectronic Materials and Technologies,Sun Yat-Sen University,Chinathe State Key Laboratory for Artificial Microstructure&Mesoscopic Physics,Peking University,China
文摘We conduct in-situ near-field imaging of propagating and localized plasmons(cavity and dipole modes) in graphene nano-resonator. Compared with propagating graphene plasmons, the localized modes show twofold near-field amplitude and high volume confining ability(- 10^6). The cavity resonance and dipole mode of graphene plasmons can be effectively controlled through optical method. Furthermore, our numerical simulation shows quantitative agreement with experimental measurements. The results provide insights into the nature of localized graphene plasmons and demonstrate a new way to study the localization of polaritons in Van der Waals materials.
基金Project supported by the National Natural Science Foundation of China(Grant No.61201075)the Natural Science Foundation of Heilongjiang Province+5 种基金China(Grant No.F2015039)the Young Scholar Project of Heilongjiang Provincial Education BureauChina(Grant No.1254G021)the China Postdoctoral Science Foundation(Grant No.2012M511507)the Science Funds for the Young Innovative Talents of Harbin University of Science and TechnologyChina(Grant No.201302)
文摘We propose an improved design and numerical study of an optimized tunable plasmonics artificial material resonator in the terahertz regime. We demonstrate that tunability can be realized with a transmission intensity as much as - 61% in the lower frequency resonance, which is implemented through the effect of photoconductive switching under photoexcitation.In the higher frequency resonance, we show that spoof surface plasmons along the interface of metal/dielectric provide new types of electromagnetic resonances. Our approach opens up possibilities for the interface of metamaterial and plasmonics to be applied to optically tunable THz switching.
基金This work was supported by the National Natural Science Foundation of China,the National Basic Re-search Program of China,Chinese Academy of Sci-ences,Anhui Initiative in Quantum Information Tech-nologies,and Basic Research Program of Shenzhen(JCYJ20150401145529035).
文摘By using a microscopic quantum model,we study theoretically different roles of nanocavity plasmons in scanning tunneling microscope(STM)induced light emission upon selective initial excitation of molecules or plasmons.The time evolution and spectroscopic properties of the emission from the coupled plasmon-molecule system in each case are studied using time-dependent quantum mater equations.When the STM tip is placed on the molecule to ensure direct carrier injection induced molecular excitation,the major role of the plasmons is to enhance the molecular emission via increasing its radiative decay rate,resulting in sharp molecule-specic emission peaks.On the other hand,when the STM tip is located in close proximity to the edge of the molecule but without direct carrier injection into the molecule,the role of the plasmon-molecule coupling is to cause destructive interferences between the two quantum objects,leading to the occurrence of Fano dips around the energy of the molecular exciton in the plasmonic emission spectra.
基金supported by the National Basic Research Program of China(Grant Nos.2012CB933004 and 2007CB936801)the National Natural Science Foundation of China(Grant Nos.11374023,61176120,and 60977015)+1 种基金the National Undergraduate Innovational Experimentation Program,Chinathe National Fund for Fostering Talents of Basic Science(NFFTBS),China(Grant Nos.J1030310 and J1103205)
文摘Polarization dependence of the coupling of excitation light to surface plasmon polaritons (SPPs) was investigated in a Ag nanoparticle-nanowire waveguide system (a Ag nanoparticle attached to a Ag nanowire). It was found that under the illumination of excitation light on the nanoparticle-nanowire junction, the coupling efficiency of light to SPPs depends on the polarization of the excitation light. Theoretical simulations revealed that it is the local near-field coupling between the nanoparticle and the nanowire that enhances the incident light to excite the nanowire SPPs. Because the shapes of the Ag nanoparticles differ, the local field intensity, and thus the excitement of the nanowire SPPs, vary with the polarization of the excitation light.
基金supported by the National Natural Science Foundation of China(Grant Nos.61176120,61378059,60977015,61422501,and 11374023)the National Basic Research Program of China(Grant Nos.2012CB933004 and 2015CB932403)Beijing Natural Science Foundation(Grant No.L140007)
文摘In this paper, we demonstrate a spin-controlled directional launching of surface plasmons at the subwavelength scale.Based on the principle of optical spin's effect for the geometric phase of light, the nanostructures were designed. The inclination of the structures decides the spin-related geometric phase and their relative positions decide the distance-related phase. Hence, the propagation direction of the generated surface plasmon polaritons(SPPs) can be controlled by the spin of photons. Numerical simulations by the finite difference time domain(FDTD) method have verified our theoretical prediction. Our structure is fabricated on the Au film by using a focused ion beam etching technique. The total size of the surface plasmon polariton(SPP) launcher is 320 nm by 180 nm. The observation of the SPP launching by using scanning near-field optical microscopy is in agreement with our theory and simulations. This result may provide a new way of spin-controlled directional launching of SPP.
基金by the National Basic Research Program of China under Grant No 2009CB929300the National Natural Science Foundation of China under Grant Nos 60725417,10804019 and 60990321+1 种基金Shanghai Science and Technology Committee under Grant Nos 08dj1400302 and 09dj1400103Japan Science and Technology Corporation(JST)Project.
文摘Au/GaAs/Au plasmonic cavities with a periodic hole array perforated in the top Au layer are studied.Propagating surface plasmons(PSPs)and localized surface plasmons(LSPs)associated with the rectangle hole shapes are found to interact and highly hybridize in the cavity structure,which eventually determines the resonance properties of the cavities.An anticrossing of resonance frequencies in the reflection spectra is observed when the frequency of PSPs approaches that of LSPs,demonstrating the strong coupling between SPPs and LSPs in the tri-layer plasmonic cavities.This work may provide hints to the plasmonic cavity design for light-harvesting optoelectronic applications.
基金Project supported by the National Basic Research Program of China(Grant No.2010CB635112)the National Natural Science Foundation of China(Grant No.10963002)the International Science and Technology Cooperation Program of China(Grant No.2009DFA02320)
文摘This paper analytically investigates the nonlinear behaviour of transverse plasraons in pair plasmas on the basis of the nonlinear governing equations obtained from Vlasov-Maxwell equations. It shows that high frequency transverse plasmons are modulationally unstable with respect to the uniform state of the pair plasma. Such an instability would cause wave field collapse into a localized region. During the collapse process, ponderomotive expulsion is greatly enhanced for the increase of wave field strength, leading to the formation of localized density cavitons which are significant for the future experimental research in the interaction between high frequency electromagnetic waves and pair plasmas.
基金Project supported by the National Key R&D Program of China(Grant No.2017YFA0303600)the National Natural Science Foundation of China(Grant Nos.11974253 and 11774248)。
文摘We study the plasmonic properties of hybrid nanostructures consisting of double vacancy defected graphene(DVDGr)and metallic nanoarrays using the time-dependent density functional theory. It is found that DVDGr with pure and mixed noble/transition-metal nanoarrays can produce a stronger light absorption due to the coherent resonance of plasmons than graphene nanostructures. Comparing with the mixed Au/Pd nanoarrays, pure Au nanoarrays have stronger plasmonic enhancement. Furthermore, harmonics from the hybrid nanostructures exposed to the combination of lasers ranged from ultraviolet to infrared and a controlling pulse are investigated theoretically. The harmonic plateau can be broadened significantly and the energy of harmonic spectra is dramatically extended by the controlling pulse. Thus, it is possible to tune the width and intensity of harmonic spectrum to achieve broadband absorption of radiation. The methodology described here not only improves the understanding of the surface plasmon effect used in a DVDGr-metal optoelectronic device but also may be applicable to different optical technologies.
基金supported by the National Natural Science Foundation of China(Grant No.11074061)
文摘We present a modified method to solve the surface plasmons (SPs) of semi-infinite metal/dielectric superlattices and predicted new SP modes in physics. We find that four dispersion-equation sets and all possible SP modes are determined by them. Our analysis and numerical calculations indicate that besides the SP mode obtained in the original theory, the other two SP modes are predicted, which have either a positive group velocity or a negative group velocity. We also point out the possible defect in the previous theoretical method in accordance to the linear algebra principle.
基金supported by National Natural Science Foundation of China (No.90405004)
文摘The longitudinal plasmons are the electrostatic collective excitations of the solid electron gas. In this paper, the dispersion relations of these plasmons for one-, two- and threedimensional electron gas are compactly derived in two approaches with uniform disturbed Coulomb potentials. The first approach is adopted usually in solid state theory that is the so-called random phase approximation (RPA) with the Lindhard dielectric function in the long-wavelength and high-frequency limits. The second method is a typical plasma fluid description that includes the electron fluid equations with the adiabatic process in the jellium model. The disturbed electrostatic (Coulomb) potential produced by the oscillation of electron density is dimensionally dependent and derived from the Poisson equation in Appendix B.
文摘In this paper we investigate the influence of the next-nearest-neighbor coupling on the spectrum of plasmon excitations in graphene. The nearest-neighbor tight-binding model was previously considered to calculate the plasmon spectrum in graphene [1]. We extend these results to the next-nearest-neighbor tight-binding model. As in the calculation of the nearest-neighbor model, our approach is based on the numerical calculation of the dielectric function and the loss function. We compare the plasmon spectrum of the two models and discuss the differences in the dispersion.
基金supported by the Smart Ideas Fund by Ministry of Business,Innovation and Employment,New Zealand through contract UOOX1802the University of Otago,by means of the University of Otago Postgraduate Publishing Bursary (Doctoral).
文摘Plasmonic resonators are widely used for the manipulation of light on subwavelength scales through the near-field electromagnetic wave produced by the collective oscillation of free electrons within metallic systems,well known as the surface plasmon(SP).The non-radiative decay of the surface plasmon can excite a plasmonic hot electron.This review article systematically describes the excitation progress and basic properities of SPs and plasmonic hot electrons according to recent publications.The extraction mechanism of plasmonic hot electrons via Schottky conjunction to an adjacent semiconductor is also illustrated.Also,a calculation model of hot electron density is given,where the efficiency of hot-electron excitation,transport and extraction is discussed.We believe that plasmonic hot electrons have a huge potential in the future development of optoelectronic systems and devices.