Tunable high-quality Fano resonance in coupled terahertz whispering-gallery-mode resonators

Fano resonance is widely discussed in designing functional terahertz components, such as sensors, filters, modulators, and group delay modules. Usually, a high quality (Q) factor and flexible tunability of Fano resonance are key requirements for these applications. Here, we present tunable terahertz Fano resonance with a Q factor of 2095 at 0.439 THz in coupled terahertz whispering-gallery-mode resonators (WGMRs). Coupling between a relatively low Q (578) quartz ring and a high Q (2095) silicon ring is employed to generate high Q Fano resonance. The resonant frequency of the Fano resonance can be actively manipulated by tuning the resonant frequency of the high Q WGMR, which is achieved through utilizing an electrical thermo-optic tuning method; meanwhile, the resonance intensity of the Fano resonance can be engineered by adjusting the coupling strength between two WGMRs. This coupled-WGMR scheme delivers tunable high Q Fano resonance and may contribute to the design of high-performance configurable terahertz devices.