The Characteristic Research On Spoof Surface Plasmons Subtitle

At lower frequencies,spoof surface plasmons can be confined on plasmonic metamaterials which are constructed by patterning the metal surfaces with subwavelength periodic features.Spoof surface plasmons can be categorized into two types,namely spoof surface plasmon polaritons and spoof localized surface plas-mons.In recent years,spoof surface plasmons have been investigated intensively due to their capabilities to transfer surface plasmons to lower frequency ranges and to induce new designs in circuits.In this thesis,we have studied some electromagnetic properties of spoof surface plasmons,in which the new physical phenom-ena and potential applications are explored.We have made experiments to verify some exotic properties of spoof surface plasmons.The main contents and contributions are listed below:· We investigate the Fano resonances between adjacent asymmetric metal structures with subwavelength textures which support spoof localized surface plasmon resonances at microwave frequencies.Numerical simulation is used to solve the extinction cross sections under different incident plane waves,in which the anisotropic and multipolar resonance modes are explored.By changing the radius of resonant element,the wide-band dipolar resonance is tuned to spectrally overlap narrow-band multipolar resonances.The destructure interferences between two modes will result in Fano resonances.· Ultrathin spiral metamaterials which support the eletric and magnetic resonances are studied.We show that the resonant wavelength is much larger than the size of the unit particle,and further find that the resonant wavelength is very sensitive to the particle's geometrical dimensions and arrangements.We re-alized the electromagnetically induced transparency with a metallic wire and ultrathin spiral metamaterial which is induced by the destructure coupling of electric dipole in metallic wire and the magnetic dipole in ultrathin spiral metamaterial.· The contribution of magnetic and electric higher-order radial eigen modes in textured metal particles are discussed.Through an effetive medium theroy and exact numeriacal simulations,we show the emer-gence of these geometrically-originated high-order radial spoof localized surface plasmon resonances.The occurrence of these modes is experimentally verified in ultrathin disks.Their spectral and near-field properties are characterized experimentally,showing an excellent agreement with theoretical predictions.· We introduce the concept of" spoof plasmon hybridization" and investigate experimentally the interaction of localized surface plasmon resonances in adjacent metal disks corrugated with subwavelength spiral pat-terns,showing that the collective modes supported by such "spoof" plasmonic system can be categorized into bonding and antibonding resonances in analogy to existing hybridization of both molecular orbitals and plasmons.These hybrid modes can be manipulated to produce enormous field enhancements by tun-ing the separation between disks or alternatively,the disk size,which effectively changes the relative gap size.· We propose a broadband and high-efficiency transition from a microstrip line to a conformal surface plasmon(CSP)waveguide that is made of an ultrathin corrugated metallic strip,to transform the guided waves into spoof surface plasmon polaritons in the microwave region.The transition consists of three parts:a convertor which converts the direction of the electric field from perpendicular to parallel to the strip,a matching area with gradient corrugations and a flaring metallic line to match both the momentum and impedance,and a CSP waveguide to support the SPP waves.· We propose a compact hybrid system which supports compound spoof surface resonances due to the coupling between spoof surface plasmon polaritons and localized surface plasmons.The system is com-posed of ultrathin metallic spiral structures for discrete spoof localized surface plasmons resonances and an ultrathin corrugated metallic strip to guide continuous spoof surface plasmon polaritons modes.We demonstrate both theoretically and experimentally that the spoof localized surface plasmons resonances can be efficiently excited and captured by the spoof surface plasmon polaritons waveguide,while the spoof surface plasmon polaritons transmissions can be judiciously controlled by the spoof localized sur-face plasmons structures.