Compact and Robust Silicon Waveguide to Hollow Metallic Waveguide Coupling using a Quarter-Wave Dielectric Slot Waveguide for mmW and THz Waves

This paper presents a novel technique for efficient waveguide coupling between a hollow metallic waveguide and a silicon dielectric rod waveguide in the 75–110 GHz range. The technique uses a short section of dielectric slot waveguide as a quarter-wave matching section to enhance robustness, reliability, compactness and yield for all-silicon terahertz integrated devices and systems, compared to those that employ conventional tapered-spike couplers. The transmission and reflection responses of the quarter-wave matched and tapered dielectric rod waveguides are presented, showing less than 2 dB loss. Reflection below -10 dB is achieved over the 75-110 GHz, reaching the lowest reflection magnitude of -25 dB at 97 GHz. The strong localization of the E-field with quarter-wave matching enables contactless coupling of mm waves, even in cases where there is a small separation.