Loss Analysis of Plasmonic Metasurfaces Using Field-Network-Joint Method

Structured metallic surfaces, also called as plasmonic surfaces, have been proposed to support spoof surface plasmon polariton (SPP) modes, which can mimic natural SPPs at optical frequencies. Complex plasmonic surfaces can provide a large degree of freedom to engineer the characteristics of SPP dispersion. However, the analysis of complex plasmonic surfaces is difficult using the existing theoretical methods, such as the effective medium model and mode matching model. Recently, an accurate field-network-joint method has been introduced into the dispersion analysis of complex plasmonic surfaces, but it only works in the lossless case. In this communication, lossy complex plasmonic surfaces are investigated based on the modified field-network-joint method. The proposed method can predict not only the dispersion relationship between the frequency and the wavenumber, but also the lossy feature of the plasmonic surface with high efficiency and accuracy. As an example, a periodic structure with biforked slits filled by a lossy medium is fabricated and measured. The calculated attenuation constant (i.e., the imaginary part of the wavenumber) of the lossy structure is nearly identical to the measured result, demonstrating the superiority of the proposed analytical method.