Widely-Tunable MEMS Phononic Frequency Combs by Multistage Bifurcations Under a Single-Tone Excitation

This paper reports the generation and evolution mechanisms of phononic frequency combs by a nonlinear modal-coupling MEMS resonator that can form one-to-three internal resonance. Through proper frequency sweeping, phenomena of frequency locking and internal resonance are first observed on the amplitude-frequency curve. The phononic frequency combs’ generation region is then confirmed to locate exactly at the strongest internal resonance region, and its turn-on procedure and conditions are carefully presented. Both forward and reverse frequency sweeps are used to demonstrate the multistage evolution of phononic frequency combs, showing comprehensive nonlinear dynamics including chaos, period-doubling bifurcation, and cyclic-fold bifurcation. These rich bifurcations allow a wide tunability in comb tooth spacing, which evolves from 25 Hz to more than 200 Hz, reaching an order of magnitude. [2024-0013]