Tunable Fano resonances at 2 μm waveband based on a single microring resonator

Development of silicon photonic devices for the 2 mu m waveband is urgent since the 2 mu m waveband has been considered as a potential communication window for next-generation optical communications. Asymmetric Fano resonances are very promising in the development of devices such as optical switches, sensors, and modulators for the 2 mu m waveband. In this paper, a Fano resonance at the 2 mu m waveband is theoretically realized by using a silicon-based microring resonator and the thermo-optic effect is employed to tune it. Utilizing this single microring resonator structure instead of the present coupled microring resonator structures, we achieve the Fano resonance with an extinction ratio of 30.5 dB and a slope ratio of 69.3 dB nm(-1) at the 2 mu m waveband. The metal heater and graphene heater are designed and optimized to achieve the Fano tuning. The thermal-optical tuning efficiencies are 0.46 nm mW(-1), 0.61 nm mW(-1) and 1 nm mW(-1) for the metal heater, the metal heater with air adiabatic slots, and the graphene heater, respectively. This work provides an effective scheme for the formation and tuning of the Fano resonance at the 2 mu m waveband, which is conducive to the development of devices and optical communication systems at the 2 mu m waveband.