| In recent years, developments have pushed the cut-off frequencies of transistors near 1 THz, enabling for the first time the design of large bandwidth transmit/receive modules. While there has been a significant interest in the research community to implement these devices, many challenges have slowed such progress. Primarily, these challenges stem from the high dielectric and metal losses many materials display in the THz spectrum. However, to implement wafer-level integrated circuits in the THz spectrum, efficient passive devices that are integration compatible must be developed. For any integrated system, many of the most important passive building blocks of the system are reduced to efficient waveguiding, filtering, and coupling between any active components, necessary measurement systems, and input sources. In this dissertation, efficient passive terahertz components, including waveguides, filters, and input couplers, are developed.;First, a method of efficiently coupling THz radiation between commercial quasi-optical THz systems and integration compatible THz components is introduced. The primary method developed is the use of high-density polyethylene focusing probes which can be easily fabricated so that they are compatible with commercial THz systems. The efficiency of the probes are then investigated when used with a simple silicon-based dielectric waveguide.;Next, dielectric ridge waveguides made of silicon are investigated for low loss THz wave propagation. A theoretical effective index method is applied to determine the modal propagation properties of the waveguides as well as the attenuation of the structures. FEM simulation is also carried out to verify these results. Various ridge waveguides made on silicon wafers are investigated through measurement and determined to provide low-loss waveguiding properties in the THz spectrum. The focus is then shifted to the design of thin-film integration compatible THz filters. These filters are designed with multi-objective evolutionary algorithms coupled with FEM modeling. Bandwidth, stopband characteristics, multi-resonance, and other properties of the filters are developed and improved through optimization. The filters are measured using a commercial THz system, and shown to match well with the optimized expectations.;Finally, another waveguiding structure is introduced which is built with thin-metal periodic structures on thin-film substrates. These structures efficiently guide THz waves along the surface of the textured metal structures. With these structures, other passive THz circuits, such as power splitters and sensors, are also developed. The waveguiding structures, as well as power splitter, are measured in conjunction with the dielectric focusing probes developed previously, and show to provide high transmission properties at specific design frequencies.;Throughout this dissertation efficient waveguides, filters, and coupling methods are introduced. These methods are compatible with current semiconductor fabrication techniques, enabling device realization directly on-wafer. In addition, all of the passive devices that are developed are simple to fabricate, as well as low-cost. Through the work presented in this dissertation, the realization of passive building blocks for on-wafer active THz circuits are developed, which in turn provides the possible realization of active on-wafer THz circuits. |
