Study On Particle Chains Transmission Characteristics Of Spoof Localized Surface Plasmon

At optical frequencies,surface plasmon polaritons are surface electromagnetic waves that travel over long distances at the extended interface between the metal and the dielectric.Localized surface plasmons are non-propagating excitations of electrons coupled with electromagnetic fields,mainly limited to metal nanoparticles or nanostructured surfaces.At lower frequencies,metals behave akin to perfect electric conductor(PEC),which do not support SPP.In order to realize the electromagnetic characteristics of SPP and LSP in the microwave and terahertz band,the transmission and localization spoof surface plasmons(Spoof LSP)are realized by using the structured metal surface.Spoof LSP has a wide range of potential applications in chemical and biological sensors,optical antennas,and electromagnetic energy transmission.Based on the electromagnetic resonance properties of metal spiral structural unit particles,the electromagnetic coupling characteristics of spiral particle dimers and the electromagnetic transmission characteristics of periodic spiral particle chains are studied.Based on the particle chain,a Y-beam splitter and a Mach-Zehnder(MZ)interferometer are designed.The main content of the paper is divided into two parts:(1)The spoof localized surface plasmon resonance characteristics of the metallic spiral structural unit particles and the coupling characteristics of the spiral structure dimer were studied.Under the excitation of the plane wave,the resonant spectrum of the unit structure is measured by the probe.The spiral structure unit has two resonance modes of electric dipole and magnetic dipole.Two adjacent spiral particles form a dimer structure,and the coupling between the two particles causes the formant to split.In the two peaks of the electric dipole split,the lower frequency mode is in phase.The higher frequency mode is out of phase;the two split modes of the magnetic dipole are just the opposite,the lower frequency mode is in phase,and the higher frequency mode is out of phase.We use the coupled mode theory to calculate and analyze the coupling characteristics of the metallic spiral dimer,and experimentally test the near-field distribution of the resonant line and the electric field.The simulation,calculation and experimental test results are in good agreement,which confirms the reliability of the research results.(2)The electromagnetic transmission characteristics of periodically aligned particle-chain straight waveguides and curved waveguides are studied,and two wave functional devices are designed.Based on the coupled mode theory,the dispersion relation of local surface plasmons along a one-dimensional finite particle chain is calculated.It is proved that the resonant spectrum transmission bandwidth is consistent with the dispersion curve and the periodically arranged particle chain waveguide can support the magnetically coupled Spoof LSP transmission.The effects of particle chain waveguides with different angle bends,different separation intervals and misalignment on electromagnetic wave propagation characteristics are studied.The particle chain waveguides show good robustness.Based on the particle chain,two wave function devices,Y-beam splitter and MZ interferometer are designed.Samples of various particle chain waveguides,bending,splitting and MZ interferometers were processed and tested.The experimental and simulation results were basically the same,and they have good practicability and application value in microwave functional devices.