Research On Effective Surface Plasmon Polaritons And Their Applications In Microwave Devices

Surface Plasmon Polaritons?SPPs?usually refer to highly confined electromagnetic waves surface modes propagating along the interface between metals and dielectrics at optical frequencies.They are a collective oscillation of free electrons in a noble metal which have the characteristics of subwavelength confinement,near field enhancement and slow wave characteristics.However,at low frequencies?Microwave,Terahertz and Mid Infrared?,metals behave like perfect electric conductor?PEC?and do not support SPPs.People have proposed an effective scheme to lower the effective surface plasmon frequencies of metals by decorating the metal surface with periodic grooves or holes,namely spoof SPPs.Recently,another solution was proposed to realize effective surface plasmon polaritons?ESPPs?between two positive dielectrics induced by structural dispersion.This paper focus on the basic theory and potential applications of ESPPs in microwave devices design.Some specifications are listed below:1.A resonator based on ELSPs is proposed.Using the effect of the structural dispersion induced ELSPs in the traditional rectangular waveguide,an air cavity with a length smaller than the lateral dimension of the rectangular waveguide is established in the rectangular waveguide.The length of the air cavity is different from the lateral dimension of the rectangular waveguide,resulting in the effective permittivity of the air in the air cavity being different from the effective permittivity of the air in the rectangular waveguide.Within a certain spectrum,the real parts of permittivity inside and outside the air cavity have opposite valuesand,ELSPs mode is realized at the interface and resonance occurs.2.We proposed a broadband energy harvesting waveguide structure based on ESPPs and conformal transformation optics.A broadband energy harvesting structure is designed in the microwave frequency band to realize the broadband energy harvesting of the TE₁₀ mode in the rectangular waveguide by utilizing the structural dispersion induced ESPPs in the conventional rectangular waveguide.3.The transmission characteristics of ESPPs in multilayer waveguide systems are analyzed and an energy tunneling waveguide structure,splitter based on ESPPs is proposed.The narrow waveguide which playing the role of the effective ENZ channel is used to connect two effective plasma waveguides,realizing the tunneling effect of the ESPPs in the straightin and 90-degree bending effective ENZ channel.In the mean time,the waveguide structure can realize flexible adjustment of the tunneling effect frequency by changing the lateral dimension of the narrow waveguide.Using the coupling effect of ESPPs mode in multi-layer waveguide system,low loss,high performance ESPPs splitter are designed.