Mechanical Resonators – Reducing Dissipation

A group of researchers has developed a method for achieving high Q factors from robust mechanical structures, significantly reducing device fabrication difficulty and enabling device operation in various environments. High-Q mechanical resonances are desired in many applications, but conventional wisdom relies on minimizing the size of mechanical resonator supporting structures, which makes the fabricated mechanical device fragile.

Integrated micro- and nano-mechanical resonators have extremely low mass and can be strongly coupled to light and matter. They are being investigated for precision metrology applications such as mass and force sensing and quantum physics research. Many of these applications rely on reducing mechanical dissipation.

Although their eigenenergy is in the continuous spectrum of lossy states, bound states in the continuum (BICs) are eigenstates with near-zero dissipation. BICs have been used in optical systems to reduce dissipation, resulting in various applications such as low-threshold lasers.

Mechanical BICs in an individual optomechanical microresonator has been proposed and experimentally observed. They broke the azimuthal symmetry of two mechanical modes, causing one of the hybrid modes to become a BIC under certain conditions.

They’ve created low-loss mechanical BIC or bound states in the continuum that can be used in engineering. The device’s tolerance for the geometry of the supporting structure is a significant advantage in micro/nanoelectromechanical system (MEMS/NEMS) applications.

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