A three million Q factor tuning fork resonator based on a vibration isolation structure

Abstract

The quality factor (Q factor) is one of the most important parameters for a resonant sensor since it determines the performance of the resonant system. The mass distribution imbalance caused by the fabrication error has a great impact on the anchor loss, and the Q factor will, thus, decrease drastically. In this work, a vibration isolation structure of the tuning fork is proposed to eliminate the influence of weight imbalance so that an ultrahigh Q factor can be obtained. With this designed vibration isolation structure, we prove that the anchor loss can be reduced significantly via numerical simulations, and we experimentally demonstrate that Qanchor increases by at least 78.6%. Moreover, the surface loss of the fused quartz tuning fork is also reduced after chemical etching, and we use interdigital electrodes for electrostatic excitation to avoid loss caused by the metal film employed in the conventional excitation method. Finally, the Q factor increases to 3 × 106, which is one of the highest test values known at present, and it is 127% larger than that of the tuning fork that uses a coated metal film for electrostatic excitation.