Parametric optimization of 3D revolver multichannel terahertz plastic waveguides using finite-difference time-domain model

Abstract

This study explores the parametric optimization of 3D-printed plastic waveguides with a revolver multichannel geometry, operating at 275 GHz. Two commercially available 3D printer filaments, polylactic acid (PLA) and thermoplastic polyurethane (TPU), were investigated. Using standard time-domain spectroscopy, the optical parameters of the materials were experimentally measured. These values were used to simulate the propagation characteristics within the waveguides via finite-difference time-domain (FDTD) method. In the simulation, a Gaussian beam was propagated inside the waveguides and the electric field amplitude was recorded. Results revealed low terahertz transmission for both waveguides, with maximum propagation distance of less than 10 mm corresponding to a power loss of 3 decibels (dB). A parametric sweep of the inner ring thickness identified 50 μm as the optimal thickness for both PLA and TPU cables, exhibiting consistent and least power loss at 10−15 dB. In contrast, thicker inner ring designs generally showed higher power losses and more erratic loss behavior. Future research recommendations include further optimization of the waveguide's cross-sectional design such as increasing/decreasing the number of inner rings ergo changing their diameter, and adding more inner ring layers to study its effect on the THz propagation.