Flexible and Dynamically Tunable Attenuator Based on Spoof Surface Plasmon Polaritons Waveguide Loaded With Graphene

This paper reports on a flexible and dynamically tunable spoof surface plasmon polariton (SSPP) attenuator for the first time. It consists of an SSPP waveguide and a graphene sandwich structure (GSS). Due to the flexibility of both the GSS and the SSPP waveguide, the attenuator yields a good flexible feature. The GSS is spread on the SSPP waveguide along the propagation direction to dissipate the SSPP wave. By applying the proper bias voltage to the GSS, the surface impedance of the GSS can be tuned while accordingly modifying the attenuation of the attenuator. Moreover, to well understand the attenuation mechanism, a theoretical analysis of SSPP waveguide based on Poynting power flow is proposed according to the structural characteristics of SSPP waveguide. All the theoretical, simulated, and measured results have proved that the proposed attenuator in this paper can achieve broadband attenuation tuning range, low return loss, and 90 degrees bendability without any obvious change in the attenuation.