A novel spoof surface plasmon polariton structure to reach ultra-strong field confinements

Ultrathin corrugated metallic structures have been proved to support spoof surface plasmon polariton (SPP) modes on two-dimension (2D) planar microwave circuits.However,to provide stronger field confinement,larger width of strip is required to load deeper grooves,which is cumbersome in modern large-scale integrated circuits and chips.In this work,a new spoof SPP transmission line (TL) with zigzag grooves is proposed.This new structure can achieve stronger field confinement compared to conventional one with the same strip width.In other words,the proposed spoof SPP TL behaves equivalently to a conventional one with much larger size.Dispersion analysis theoretically indicates the negative correlation between the ability of field confinement and cutoff frequencies of spoof SPP TLs.Numerical simulations indicate that the cutoff frequency of the proposed TL is lower than the conventional one and can be easily modified with the fixed size.Furthermore,two samples of the new and conventional spoof SPP TLs are fabricated for experimental demonstration.Measured S-parameters and field distributions verify the ultra-strong ability of field confinement of the proposed spoof SPP TL.Hence,this novel spoof SPP structure with ultra-strong field confinement may find wide applications in microwave and terahertz engineering.

Active odd-mode-metachannel for single-conductor systems

Although tremendous efforts have been devoted to investigating planar single-conductor circuits,it remains challenging to provide tight confinement of electromagnetic field and compatibility with active semi-conductor components such as amplifier,harmonic generator and mixers.Single-conductor spoof surface plasmon polariton(SSPP)structure,which is one of the most promising planar single-conductor transmission media due to the outstanding field confinement,still suf-fers from the difficulty in integrating with the active semi-conductor components.In this paper,a new kind of odd-mode-metachannel(OMM)that can support odd-mode SSPPs is proposed to perform as the fundamental transmission chan-nel of the single-conductor systems.By introducing zigzag decoration,the OMM can strengthen the field confinement and broaden the bandwidth of odd-mode SSPPs simultaneously.More importantly,the active semi-conductor amplifier chip integration is achieved by utilizing the intrinsic potential difference on OMM,which breaks the major obstacle in im-plementing the single-conductor systems.As an instance,an amplifier is successfully integrated on the single-conductor OMM,which can realize both loss compensation and signal amplification.Meanwhile,the merits of OMM including crosstalk suppression,low radar cross section(RCS),and flexibility are comprehensively demonstrated.Hence,the pro-posed OMM and its capability to integrate with the active semi-conductor components may provide a new avenue to fu-ture single-conductor conformal systems and smart skins.

Anisotropic coding metamaterials and their powerful manipulation of differently polarized terahertz waves

Metamaterials based on effective media can be used to produce a number of unusual physical properties(for example,negative refraction and invisibility cloaking)because they can be tailored with effective medium parameters that do not occur in nature.Recently,the use of coding metamaterials has been suggested for the control of electromagnetic waves through the design of coding sequences using digital elements‘0’and‘1,'which possess opposite phase responses.Here we propose the concept of an anisotropic coding metamaterial in which the coding behaviors in different directions are dependent on the polarization status of the electromagnetic waves.We experimentally demonstrate an ultrathin and flexible polarization-controlled anisotropic coding metasurface that functions in the terahertz regime using specially designed coding elements.By encoding the elements with elaborately designed coding sequences(both 1-bit and 2-bit sequences),the x-and y-polarized waves can be anomalously reflected or independently diffused in three dimensions.The simulated far-field scattering patterns and near-field distributions are presented to illustrate the dual-functional performance of the encoded metasurface,and the results are consistent with the measured results.We further demonstrate the ability of the anisotropic coding metasurfaces to generate a beam splitter and realize simultaneous anomalous reflections and polarization conversions,thus providing powerful control of differently polarized electromagnetic waves.The proposed method enables versatile beam behaviors under orthogonal polarizations using a single metasurface and has the potential for use in the development of interesting terahertz devices.