Integrated tuning fork nanocavity optomechanical transducers with high fMQM product and stress-engineered frequency tuning

• Published in: Applied physics letters 2015-09, Vol.107 (13)
• Main Authors: Zhang, R., Ti, C., Davanço, M. I., Ren, Y., Aksyuk, V., Liu, Y., Srinivasan, K.
• Format: Article
• Language: English
• Subjects: Applied physics; Atomic force microscopy; Clamping; Damping; Q factors; Stresses; Temporal resolution; Transducers; Tuning
• ISSN: 0003-6951; 1077-3118
• DOI: 10.1063/1.4932201

Cavity optomechanical systems are being widely developed for precision force and displacement measurements. For nanomechanical transducers, there is usually a trade-off between the frequency (fM) and quality factor (QM), which limits temporal resolution and sensitivity. Here, we present a monolithic cavity optomechanical transducer supporting both high fM and high QM. By replacing the common doubly clamped, Si3N4 nanobeam with a tuning fork geometry, we demonstrate devices with the fundamental fM≈29 MHz and QM≈2.2×105, corresponding to an fMQM product of 6.35×1012 Hz, comparable to the highest values previously demonstrated for room temperature operation. This high fMQM product is partly achieved by engineering the stress of the tuning fork to be 3 times the residual film stress through clamp design, which results in an increase of fM up to 1.5 times. Simulations reveal that the tuning fork design simultaneously reduces the clamping, thermoelastic dissipation, and intrinsic material damping contributions to mechanical loss. This work may find application when both high temporal and force resolution are important, such as in compact sensors for atomic force microscopy.