| With the demand of wider bandwidths and higher bit rates, the use of terahertz frequencies for wireless communications has experienced a surge of attention in recent years. Due to its low absorption and low dispersion, dry gas has been proven to be the best medium to deliver terahertz radiation. To date, various THz communication systems with carrier frequencies smaller than 0.6THz and data transmission rates of 100Gbit/s have been developed and investigated based on free-space propagation (FSP). However, applications of these THz communication systems are still limited due to inherent challenges posed by the free space propagation modality, such as strong dependence on atmospheric conditions, rapid divergence of the THz beams especially at lower frequencies, and demand of professional alignment and optic hardwares. Additionally, due to strong directionality of the THz beams, wireless communications access to partially blocked areas can be problematic, thus, requiring additional THz steering solutions for reliable communications. On the other hand, dielectric fibers and waveguides offer solutions to the limitations caused by free-space propagation. Particularly, light propagates through sealed THz fibers, thus, influence of the atmospheric conditions on the communication link quality is minimized. Additionally, THz fibers are flexible, hence, allowing access to even physically obstructed areas. Finally, THz fiber size is typically comparable to the wavelength of light, thus enabling highly compact communication links with small footprint. However, no such waveguide-assisted THz communication system currently exists. The main culprits are high absorption and dispersion of THz waveguides. In the past decade, various THz fibers have been proposed for low loss guidance, and hence the loss reduction in THz fibers can be considered as a solved problem. However, dispersion management in THz fibers has been rarely studied and remains unsolved. In this thesis, I will explore several types of dielectric waveguides for both loss and dispersion reduction in terahertz frequency range. First, I present a novel hollow-core terahertz PBG waveguide that uses hyperuniform disordered reflectors. The main motivation of the proposed waveguide is to explore the possibility of designing hollow-core waveguides that feature spectrally broad bandgaps which are potentially superior to those attainable with purely periodic structures. |
