Two-Conductor Ports Enabling Broadband Operation of Substrateless Microscale Silicon Waveguides

We extend the operation bandwidth of substrateless all-silicon waveguides beyond the single-mode region. This requires a suitably broadband port-access scheme, as well as careful management of undesired higher-order modes. It is found that a length of two-conductor waveguide serves both purposes. In this way, we experimentally demonstrate broadband power transfer between dielectric waveguides and numerically investigate suppression of higher-order modes. This three-dimensional solid-metal two-conductor waveguide shows promise as a package-external terahertz port, to address the 40% relative- bandwidth bottleneck that is currently imposed by hollow metallic waveguides. This represents a step towards efficient handheld terahertz systems that fully exploit the broad available spectrum.