Experimental realization of tunable Fano resonances in two coupled silicon micromechanical resonators

Fano resonances originate from the interaction of a discrete state with a continuum of propagation modes. They have been observed in various quantum and classical systems. Here, we provide experimental observation of the Fano resonance in two coupled micromechanical oscillator systems. The system consists of a pair of electrostatically coupled silicon micromechanical resonators. The coupling strength between the two resonators and their stiffness can be electrically tuned. The damping of one resonator can be regulated by an external proportional feedback control system. We have achieved the switching from the Lorentzian line shape to the Fano line shape, indicating that the quality factor of the Fano resonance is more than three times that of the Lorentzian resonance. This work supplies a flexible platform for exploring the physics of Fano resonances in a mechanical system and paves the way for developing a new generation of silicon resonant sensors with superior resolution.