FEM Characterization of Terahertz Wave on Metal Wire Waveguides

Deibel, J.A., Wang, K., Escarra, M.D., Mittleman, D.M.
Department of Electrical and Computer Engineering, Rice University, Houston, TX, USA

The terahertz (THz) region of the electromagnetic spectrum (100 GHz to 10 THz) remained relatively unexplored until developments in ultrafast laser technology provided techniques for the generation and detection of THz radiation.

Recently, simple metal wires were found to be effective terahertz waveguides that exhibited very low loss and dispersion. The THz radiation propagates along the surface of the wire’s cylindrical geometry. This propagation is very similar to the wave phenomena described by Sommerfeld and has also been described as an azimuthally polarized surface plasmon. Both theories do not agree with experimental studies of the attenuation versus frequency.

We employ the Finite Element Method (FEM) and specifically FEMLAB to study the excitation and propagation of terahertz radiation along metal wires. Radially polarized waves at THz frequencies are excited and launched down metal wires and allowed to propagate. We also demonstrate FEM simulations of novel excitation schemes including scattering experiments and novel photoconductive antenna geometries.

Where possible, these results are compared with experimental ones. Both the Finite Element Method and FEMLAB are shown to be powerful tools for studying the propagation of guided terahertz radiation.