Integrated resonant cavities on substrateless terahertz dielectric waveguide platform

We present two resonant cavity designs for an all-silicon substrateless dielectric waveguide platform based on effective medium implementation. These include a disk resonator and a photonic crystal cavity. The substrateless dielectric waveguide platform realizes very low absorption that is beneficial to achieve a high-Q resonance for these cavities. The measurement results of the disk resonator show a Q-factor of 559 at 276.3 GHz, while the photonic crystal cavity show strong resonance behavior and high transmission at 279.8 GHz. Additionally, the photoconductive tuning of the resonance of these cavities is demonstrated. The 276.3 GHz disk resonator and the 279.8 GHz photonic crystal cavity both show strong tunability of the resonance when selected parts are illuminated with moderate optical power. These cavities can be employed in various terahertz applications including sensing, switching, and modulation.