π-Network Transmission Line Model for Plasmonic Waveguides with Cavity Structures

We propose a π-network transmission line model to investigate plasmonic metal-dielectric-metal (MDM) waveguides side-coupled with cavity structures. This model can effectively describe the transmission characteristics as a function of coupling distance in our proposed structures. And the π-network transmission line model is promoted to describe transmission spectra and scattering parameters in infinite element structures and periodic structures, which are confirmed by the finite-difference time-domain (FDTD) simulation results. In addition, the slow-light effects in waveguide side-coupled with periodic cavity structures are researched in our paper. And we first compare the slow-light effects in the plasmonic waveguide side-coupled with cavity structures and stub structures. These observations could be helpful to fundamental research and applications for integrated plasmonic devices.