Future Wireless THz Communication Devices and Systems

Wireless communication and positioning systems are ubiquitous and an indispensable part of the modern-society infrastructure. The capacity of the used radio-frequency (RF) spectrum is gradually being exhausted. An expansion to sub-THz and THz frequencies is therefore inevitable, considering the growing demand for wireless communication/positioning systems. This expansion is however hampered by a lack of low-cost and energy efficient devices. To meet this demand, solid-state devices are required. One of the most promising candidates at sub- THz and THz frequencies are resonant-tunnelling-diode (RTD) oscillators which operate currently up to almost 2 THz. RTD oscillators mutually coupled or injection locked (IL) in an array generate output powers up to 10 mW. For enabling THz communication/positioning, an accurate phase/frequency control of the oscillators is mandatory, as it could be done by IL. However, there are two problems. First, the IL analysis currently remains at semi-quantitative level at most. Second, the internal IL- oscillator parameters (control voltages, oscillation amplitude, phases, etc.) are basically not measurable at sub-THz and THz frequencies and can be only roughly estimated. To overcome these problems, we aim to establish an accurate analysis/modelling framework for IL, perform precise IL measurements, and demonstrate phase/frequency control in communication/positioning with IL RTD oscillators for the first time. This comprises: (i) work out accurate semi-analytical models, (ii) numerical IL simulation techniques, (iii) precise IL measurement methods and model verification, starting with frequency-downscaled RTD oscillators at 50 GHz, for which these measurements are currently feasible. Demonstration of coherent and non-coherent IL communication/positioning (iv) completes this project. To make this project a success, the expertise of TU Wien (TUW) in the micro- and nano-fabrication and physics-level modelling of THz devices, RF/THz measurements, and communication systems is complemented by FH Oberösterreich`s (FHOÖ) in numerical and symbolic modeling, simulation and optimization know-how of RF circuits and devices. The structured systematic doctoral program contains study courses, joint weekly seminars for PhD students, joint supervision, lab rotation, participation in international summer schools and conferences, etc. Dedicated courses will cover the state-of-the-art in the specific research fields of the supervisors. The project should establish a long-term joint doctorate program between TUW and FHOÖ. Complementarity of the participants research fields will provide foundation for subsequent long- term collaborations, particularly in the field of THz technology and related applications.