Bound states in the continuum (BICs) are waves perfectly confined in the continuous spectrum of radiating waves without interaction. This paper experimentally observed BICs in the micromechanical domain using a CMOS-compatible, wheel-shaped optomechanical microresonator on a silicon chip. The BIC arises from destructive interference between two dissipative mechanical modes under broken azimuthal symmetry. These BICs are achievable in devices with large, robust supporting structures, simplifying fabrication and enabling versatile applications. The results demonstrate a new approach to phonon trapping in micromechanical structures with dissipation channels, leading to long phonon lifetimes beneficial for mechanical oscillators, sensors, and quantum information processors.

Yue Yu, Xiang Xi, Xiankai Sun