Efficient mode coupling between dielectric and metallic hollow waveguides is critical in the development of integrated terahertz systems based on all‐silicon platforms. Conventional dielectric linear tapers, while commonly used, require long and thin structures, typically 3 to achieve a low coupling loss, resulting in increased device footprint and a high risk of mechanical breakage during fabrication and alignment. In this work, we present two compact all‐silicon couplers, each leveraging the combined principles of dielectric rod antennas and slot waveguides. The proposed designs feature compact footprints of only 0.5 in length for operation across 220–330 GHz and demonstrate an average coupling loss of –1.25 dB across this band. Compared to conventional linear tapers, the proposed design reduces footprint, improves mechanical robustness and ease of alignment. Experimental validation through terahertz communications measurements demonstrates bit error rates (BER) below for the out‐of‐plane polarization and below for the in‐plane polarization at 275 GHz with a 7 Gbit/s data rate, and stable performance at a BER of under high signal‐to‐noise conditions. The proposed couplers facilitate efficient mode conversion between different waveguides, making them valuable components for system‐level integration in future terahertz communications frontends.
Chen et al. (2026) studied this question.