Design and fabrication of 3D high-contrast metastructure THz cage waveguides

We have designed new THz metastructure waveguides on Si wafers, aimed for low propagation loss and integration with Si-based integrated circuits. The waveguide has a round cross-sectional hollow-core, surrounded by high reflectioncladding- walls formed by high-contrast metastructure gratings. We developed a new fabrication technique to fabricate such a 3D metastructure cage waveguide structure. The waveguide is built using the entire wafer thickness which involves deep Si etching of periodically spaced holes and using isotropic undercut etching to create a connecting a line of etched spheres in the middle of the wafer to form the waveguide’s hollow core, then deep etch the high-contrast grating through the entire wafer thickness to form the cladding for the waveguide. We have successfully modeled and fabricated such a waveguide structure. The next step is to experimentally test and characterize the waveguide in the THz spectrum range.