Metasurfaces offer innovative approaches for manipulating electromagnetic waves at subwavelength scales.Recent advancements have focused on toroidal dipole(TD) and quasi-bound state in the continuum(quasi-BIC) modes,w...Metasurfaces offer innovative approaches for manipulating electromagnetic waves at subwavelength scales.Recent advancements have focused on toroidal dipole(TD) and quasi-bound state in the continuum(quasi-BIC) modes,which are particularly attractive due to their capacity to enhance light-matter interaction.However,most metasurfaces with TD and quasi-BIC modes exhibit passive electromagnetic responses after fabrication,limiting their practical applications.This study presents both numerical and experimental investigations that demonstrate the active control of TD and quasi-BIC modes through the integration of symmetric and asymmetric aluminum dumbbell aperture arrays with the phase-change material Ge2Sb2Te5(GST).The symmetric hybrid dumbbell aperture array shows a pronounced TD response within the terahertz frequency range.In contrast,modifying the geometric parameters to disrupt the structural symmetry induces a quasi-BIC mode in the asymmetric hybrid dumbbell aperture array.Furthermore,as GST undergoes a phase transition from its amorphous to crystalline state,both TD and quasi-BIC modes become dynamically tunable,driven by changes in the conductivity of GST.Notably,significant modulation of the transmitted terahertz wave occurs around the frequencies corresponding to the TD and quasi-BIC modes during the GST phase transition.Symmetric and asymmetric hybrid dumbbell aperture arrays provide a versatile platform for generating tunable TD and quasi-BIC modes,with promising applications in terahertz modulators and filters.展开更多
Anapole states, accompanied by strong suppression of light scattering, have attracted extensive attention in recent years due to their supreme performance in enhancing both linear and nonlinear optical effects. Althou...Anapole states, accompanied by strong suppression of light scattering, have attracted extensive attention in recent years due to their supreme performance in enhancing both linear and nonlinear optical effects. Although both low-and high-order anapole states are observed in the dielectric particles with high refractive index, so far few studies have touched on the topic of plasmonic anapole states. Here we demonstrate theoretically and numerically that the ideal plasmonic anapole states(strong suppression of electric dipole scattering) can be achieved in metallic metamolecules via increasing the coupling strength between Cartesian electric dipole and toroidal dipole moments of the system. The increasing coupling is based on compensation of ohmic losses in a plasmon system by introducing of a gain material, the influence of which is well described by the extended coupled oscillator model. Due to suppression of dipole radiation losses, the excitation of anapole states in plasmonic systems can result in enhancement of the near fields in subwavelength spatial regions outside of nanoparticles. That is especially important for developments of nonlinear nanophotonic and plasmonic devices and active functional metamaterials, which provide facilities for strong light energy concentration at the nanoscale. Development of the considered anapole effect with increase of metamolecule components is discussed.展开更多
The interaction between magnetic quantum emitters and the local electromagnetic environment is a promising method to manipulate the spontaneous emission.However,it is severely limited by the weak interactions between ...The interaction between magnetic quantum emitters and the local electromagnetic environment is a promising method to manipulate the spontaneous emission.However,it is severely limited by the weak interactions between the magnetic component of light and natural materials.Herein,we demonstrate that the special type of anapole states associated with the“onefold”electric toroidal dipole moment can be excited by efficient interaction between magnetic dipole emitters and silver oligomers.Based on magnetic anapole states,the radiative power is effectively suppressed with significant coupling between the emitter and the silver nonamer,physically providing an ideal playground for the study of non-radiative transitions.These findings not only introduce magnetic anapoles to plasmonics but also open a door for the development of new high-performance magnetic-dipole-based optoelectronic devices.展开更多
基金National Natural Science Foundation of China(12304434, 12304433, 12204446, 12004361, 12004362)Natural Science Foundation of Zhejiang Province(LY22A040006)+1 种基金Fundamental Research Funds for the Provincial Universities of Zhejiang (2023YW06,2023YW01)State Key Laboratory of Millimeter Waves(K202429)
文摘Metasurfaces offer innovative approaches for manipulating electromagnetic waves at subwavelength scales.Recent advancements have focused on toroidal dipole(TD) and quasi-bound state in the continuum(quasi-BIC) modes,which are particularly attractive due to their capacity to enhance light-matter interaction.However,most metasurfaces with TD and quasi-BIC modes exhibit passive electromagnetic responses after fabrication,limiting their practical applications.This study presents both numerical and experimental investigations that demonstrate the active control of TD and quasi-BIC modes through the integration of symmetric and asymmetric aluminum dumbbell aperture arrays with the phase-change material Ge2Sb2Te5(GST).The symmetric hybrid dumbbell aperture array shows a pronounced TD response within the terahertz frequency range.In contrast,modifying the geometric parameters to disrupt the structural symmetry induces a quasi-BIC mode in the asymmetric hybrid dumbbell aperture array.Furthermore,as GST undergoes a phase transition from its amorphous to crystalline state,both TD and quasi-BIC modes become dynamically tunable,driven by changes in the conductivity of GST.Notably,significant modulation of the transmitted terahertz wave occurs around the frequencies corresponding to the TD and quasi-BIC modes during the GST phase transition.Symmetric and asymmetric hybrid dumbbell aperture arrays provide a versatile platform for generating tunable TD and quasi-BIC modes,with promising applications in terahertz modulators and filters.
基金Natural Science Foundation of Zhejiang Province(LQ21A040012)National Natural Science Foundation of China(11804323,12004362)Deutsche Forschungsgemeinschaft(DFG,German Research Foundation)under Germany’s Excellence Strategy within the Cluster of Excellence Phoenix D(390833453)。
文摘Anapole states, accompanied by strong suppression of light scattering, have attracted extensive attention in recent years due to their supreme performance in enhancing both linear and nonlinear optical effects. Although both low-and high-order anapole states are observed in the dielectric particles with high refractive index, so far few studies have touched on the topic of plasmonic anapole states. Here we demonstrate theoretically and numerically that the ideal plasmonic anapole states(strong suppression of electric dipole scattering) can be achieved in metallic metamolecules via increasing the coupling strength between Cartesian electric dipole and toroidal dipole moments of the system. The increasing coupling is based on compensation of ohmic losses in a plasmon system by introducing of a gain material, the influence of which is well described by the extended coupled oscillator model. Due to suppression of dipole radiation losses, the excitation of anapole states in plasmonic systems can result in enhancement of the near fields in subwavelength spatial regions outside of nanoparticles. That is especially important for developments of nonlinear nanophotonic and plasmonic devices and active functional metamaterials, which provide facilities for strong light energy concentration at the nanoscale. Development of the considered anapole effect with increase of metamolecule components is discussed.
基金Natural Science Foundation of Zhejiang Province(LQ21A040012)Natural Science Foundation of Hunan Province(2021JJ20076)+1 种基金National Natural Science Foundation of China(11704416,12004362)Changzhou Basic Research Program(CJ20199009)。
文摘The interaction between magnetic quantum emitters and the local electromagnetic environment is a promising method to manipulate the spontaneous emission.However,it is severely limited by the weak interactions between the magnetic component of light and natural materials.Herein,we demonstrate that the special type of anapole states associated with the“onefold”electric toroidal dipole moment can be excited by efficient interaction between magnetic dipole emitters and silver oligomers.Based on magnetic anapole states,the radiative power is effectively suppressed with significant coupling between the emitter and the silver nonamer,physically providing an ideal playground for the study of non-radiative transitions.These findings not only introduce magnetic anapoles to plasmonics but also open a door for the development of new high-performance magnetic-dipole-based optoelectronic devices.
