Tunable Surface Phonon Polariton based THz Cavity

Designing and realizing switchable cavities at the infrared and THz frequencies is crucial for achieving novel integrated photonic circuits. Semiconductors like SiC support the propagation of surface phonon polaritons with the ability to tune carrier concentrations via doping. In this manuscript, we investigate the tunability of coupled surface-phonon-plasmon polariton waves inside an elliptical cavity build from a metal-semiconductor heterostructure. We theoretically study the impact of the extra n- and p-carrier doping on the resonant modes of the cavity and we show that for certain cavity modes a Purcell factor of 180 and an on/off switching behavior can be achieved via charge injection. The cavity mode tuning range spans approximately 13 times the resonance width.