Infinity Additive Manufacturing of Microstructured Fibers for THz Communications

The Terahertz (THz) spectral range (0.1-10 THz), located between microwave and infrared spectral ranges, has attracted widespread attention over the past two decades owing to the advances in both generation and detection technologies of THz radiation, as well as the unique properties of THz waves, such as the non-ionizing nature, large bandwidth, strong absorption by water molecules, high directivity, etc. In particular, the THz frequency band is expected to provide solutions for next-generation high-speed communications. In this scenario, wireless links are undoubtedly a particularly convenient modality for mobile end users while transmitting large data volumes. However, there are still major obstacles hindering the practical application of free space wireless THz communication systems. Nevertheless, the seamless integration of THz wireless links and fiber-assisted links can provide better reliability and diversity for next-generation communication systems. To achieve this, high-performance advanced THz fiber/waveguide is an indispensable and important component. The main objective of this thesis is to develop advanced microstructured THz fibers for practical applications in THz communications, and to explore novel additive manufacturing techniques for the continuous fabrication of advanced THz fibers featuring complex transverse geometries, thus pushing the field of THz communications one step closer to reality. The thesis starts with a comprehensive review of the scientific literature on the subject of wired THz communications. This review presents most of the progress in the field of wired THz communications in the past two decades, covering communication links ranging from a few centimeters to more than ten meters. A variety of fibers/waveguides and functional devices for THz communication applications are introduced, including photonic crystal waveguides, topological valley photonic crystal waveguides, effective-medium-cladded waveguides, dielectric interconnects, all-dielectric and hybrid dielectric/metal hollow-core fibers, subwavelength rod-in-air fibers, graded-index porous fibers, two-wire waveguides, directional couplers, splitters, dispersion compensators, frequency/polarization-division multiplexers, etc. Subsequently, a comprehensive literature review on the application of additive manufacturing (3D printing) techniques in THz fiber/waveguide fabrication is presented.