Additive Manufacturing of Terahertz Waveguide Components for THz Sensing and Communications

The terahertz band ranging from 0.1-10 THz occupies the last relatively underutilized part of the electromagnetic spectrum. Placed in the switching region between electronics and photonics, the “THz gap” has garnered attention for potential applications in sensing, communications, imaging, and spectroscopy during the past decades. To transform the THz technology from theory to practice, the efficient THz waveguide component for THz beam steering and manipulating is one of the missing pieces of the puzzle. However, due to the unavailability of conventional electronics and photonics solutions such as metal transmission lines and silica fibers in the THz range, the lack of universal design standards and fabrication routes has trapped THz waveguide components in the development stage. Considering that the waveguide scale is typically comparable to the wavelength of light, spanning from 3 mm to 30 μm for THz radiation, additive manufacturing techniques incorporating continuously improving resolution have gradually become a promising solution to reproduce THz waveguides with complicated 3D structures and subwavelength features. This has led to the possible realization of new advances in the design and fabrication of THz waveguide components. In this study, we focused on 3D printed THz dielectric fibers and plasmonic waveguides. Among the primary objectives was the development of a real-time fluidic sensor based on a THz photonic bandgap Bragg dielectric fiber. While another was the development of THz optical components and circuits based on two-wire plasmonic waveguides for THz communication. We begin this thesis with a scientific literature review on subjects of the involvement of THz waveguide components in THz sensing and communications, as well as applications of 3D printing in THz waveguides. First, four types of commonly used THz waveguides, that is, polymer fibers, plasmonic waveguides, rectangular waveguides, and waveguides on planar silicon substrates, are briefly discussed along with their guiding mechanisms and applicable manufacturing techniques. Subsequently, we shift the focus to applications of THz waveguide components in the field of THz sensing and communications. In terms of sensing, several THz waveguide-based sensor designs, as well as the development and potential application of photonic bandgap Bragg waveguides have been discussed.