[26a-E101-1~6] 3.9 Terahertz technologies

▼ [26a-E101-3] Suitability of metallic materials for metal-coated dielectric terahertz waveguides

〇Yuyuan Huang¹, Kuniaki Konishi², Momoko Deura¹, Yusuke Shimoyama¹, Junji Yumoto², Makoto Kuwata-Gonokami², Yukihiro Shimogaki¹, Takeshi Momose¹ (1.Univ. of Tokyo. Sch. of Eng., 2.Univ. of Tokyo. Sch. of Sci.)

Keywords:Terahertz waveguides, Suitable metal

Terahertz wave devices are the essential components for controlling THz waves, which were aimed for the application of beyond 5th and 6th generation communication systems. The devices have sub-millimeter-scale three-dimensional (3D) and high-aspect-ratio structures. Recently, 3D printing of dielectrics (i.e. polymer) emerges due to its improved resolution down to ten micrometers. Thus, the combination of 3D printing of polymer substrate and metal film coating enables the fabrication of metal-coated dielectric THz wave devices. In addition, a clear-cut understanding of the film thickness to achieve the desired performance of metal-coated dielectric THz waveguides is essential. We previously developed the physical model for anticipating the two key parameters determining waveguide performance, which were critical film thickness performing like metallic waveguides and the propagation loss in films with thicknesses greater than critical film thickness (α_CT). The suitable metallic material is the remaining concern. Since dominant factors to determine the propagation loss were different in GHz and THz regions, which were penetration loss in GHz, while the ohmic loss in THz (i.e. thickness-dependent conductivity), suitable metals in the THz region should be carefully determined. We, therefore, selected suitable metallic material using our model under the assumption of the same film quality.
The physical model for anticipating the two key parameters in the metal-coated dielectric parallel-plate waveguide was used. Cu was found to have the smallest critical thickness and comparable α_CT with Ag that has the smallest value. Considering that the material cost and availability, Cu was considered to be a suitable material. As both two key parameters depend on film quality, the impact of film quality on these parameters will also be discussed onsite.