Experimental study and simulation analysis of transmission characteristics of terahertz metal wire waveguides

Abstract

Terahertz waves are between microwave and infrared, and currently, terahertz waves are mainly transmitted in free space. Metal wire waveguides have been widely studied for their outstanding transmission characteristics such as low loss and low dispersion. This study first selected copper wires as the research samples based on the skin depth of terahertz waves on different metal wire surfaces. Then, an adjustable metal wire waveguide transmission characteristic testing optical path was built based on the terahertz time-domain spectroscopy system. The time-domain signals transmitted through single/double copper wires with different radii, lengths, and port states were collected. Finally, the finite element method was used to analyze the transmission characteristics of single/double copper wires with different radii, lengths, and port states Simulate the transmission characteristics of single/double copper wires with different degrees of deformation in the air domain. The experimental results indicate that transmission loss increases with the increase of copper wire length, and the thinner the metal wire, the slower the transmission speed; The influence of port shape on transmission characteristics is not as significant as that of length variation; The thicker the bimetallic wire, the faster the transmission speed. The simulation results show that when terahertz waves are transmitted on a single metal wire, the electric field is mainly distributed on the surface of the metal wire, and the finer the metal wire, the smaller the mode field area of the surface plasmon; When the metal line becomes elliptical, the mode field is mainly distributed at both ends of the major axis; When terahertz waves are transmitted in bimetallic wires, the mode field is mainly distributed between the two wires, and the farther the distance, the smaller the mode field area. This study combines experimental and simulation analysis methods to study the terahertz transmission characteristics of single and bimetallic wires, providing a reference for the subsequent development of efficient terahertz metal waveguides.