Terahertz Parallel-Plate Ladder Waveguide With Highly Confined Guided Modes

Abstract

In this paper, we introduce a parallel-plate ladder waveguide (PPLWG) for THz waves. The characteristics of the guided modes of this structure which belong to the category of spoof surface plasmons are studied using the generalized multipole technique and its potential applications are discussed. Moreover, the proposed structure is experimentally investigated in a THz time-domain spectroscopy system and a comparison between the calculated and measured amplitude and phase characteristics is given. It is shown that the dominant mode of the PPLWG can be excited by an incident focused beam and a high degree of field confinement in the THz regime can be achieved.