Tunable High-Quality Fano Resonance in Coupled Terahertz Whispering-Gallery-Mode Resonators

Abstract: Fano resonance is widely discussed in designing novel terahertz components, such as sensors, filters, modulators, and group delay modules. Usually, 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 the 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 high Q tunable Fano resonance and may contribute to the design of high-performance configurable terahertz devices.