12.8 million Q factor cylindrical resonator with optimized thermoelastic dissipation after thin films coating

Abstract

The influence of various thicknesses and combinations of different metal films coated on the surface of fused silica cylindrical resonators subjected to thermoelastic dissipation was investigated. For this purpose, the impact of thermoelastic damping (TED) on the quality factor (Q factor) was first quantified by solving the strongly coupled solid-thermodynamic field problem via the finite element method, with a focus on the TED behavior in thin-film-coated cylindrical resonators. To address practical application requirements, a thermoelastic loss model for bimetallic-coated cylindrical resonators was established. Following mesh optimization, variations in coating material parameters and thickness were simulated, and their correlation with the thermoelastic Q factor (QTED) was systematically analyzed. Furthermore, comparative simulations of QTED were conducted for three bimetallic coatings (Cr/Au, Ti/Au, and Ni/Au) with varying thicknesses, providing theoretical foundations for coating optimization. A laser Doppler vibrometer was utilized for measuring the Q factor of resonators before and after ultrathin sputtered bimetallic coating. The results demonstrated that the Cr/Au-coated cylindrical resonator achieved a Q factor of 12.8 × 106 with a retention rate of 70%, representing the highest reported Q factor for a metallized cylindrical resonator to date. This paper illustrates a novel low-loss thin-film technology pathway, which is envisaged to greatly increase the ultimate precision achievable in cylindrical resonator gyroscopes.