Planar Plasmonic Terahertz Waveguide Based Upon One Dimensional Array of Pyramidal Corrugations and Refractive Index Sensing

We examine the refractive index sensor ability of the terahertz surface plasmon modes supported by a planar plasmonic terahertz (THz) waveguide. The waveguide is comprised of one-dimensional array of periodically arranged subwavelength scale pyramidal corrugations resulting in a plasmonic metamaterials waveguide. The waveguide exhibits strong field confinement along with the corrugated pattern. We have analyzed the dispersion property and quality factor of the fundamental as well as higher-order modes of the waveguide. In order to examine sensor capability, we used analytes of different refractive indices and observed a corresponding frequency shift. We further analyze the sensitivity of all the modes for the given volume of analyte and compare their sensing performance. We have employed the semi-analytical model to understand the numerical observations. The proposed waveguide approach can potentially result in highly sensitive refractive index sensors at terahertz frequencies.