Broadband point source for terahertz silicon guides

There is a need for compact, broadband, efficient radiators for terahertz integrated circuits, to serve as feed for large-aperture quasi-optics, or as antenna elements in phased arrays. We present a condensed, subwavelength progressive transition between a terahertz micro-scale dielectric waveguide and a dielectric slot radiating aperture. The result is an endfire point-source radiator spanning >2.2:1, from <185 GHz to 410 GHz, which is fabricated in a single etch step from a high-resistivity float-zone intrinsic silicon wafer. The radiation phase center deviates by just ∼500 μm across the operation bandwidth—less than one free-space wavelength.