Tunable acoustic resonances: From weak to strong coupling regime

Tunable interaction strength between a side-coupled ring resonator and an acoustic waveguide structure is demonstrated. Fano resonances in the weak coupling regime are observed from the interference between a discrete state of the ring resonator and a continuum state of the waveguide. As the distance between the two structures is decreased, a transition from weak to strong coupling regime is obtained, where we observe splitting in the transmission spectrum and Rabi oscillations in the temporal behavior for smaller values. The findings of the finite-element method simulations are supported with the results obtained from a simple theoretical model in which one can explain the dynamics of the hybrid modes. The results can contribute to device applications in acoustic sensors, switches, and surface acoustic wave integrated circuits.