High-Q fused silica birdbath and hemispherical 3-D resonators made by blow torch molding

This paper presents a novel 3-D fabrication process of microstructures using high-Q materials. The key feature of this process is the use of a blow torch that can provide intensive localized heat up to 2500°C in a very short time (<;10 sec), above the melting temperatures of many high-Q materials such as fused silica. Surface roughness of 5.3 Å is realized in fused silica, which is crucial for high optical and mechanical quality factors (Q). We demonstrate the fabrication of micro hemisphere and half-toroid (birdbath) geometries from 100μm-thick fused silica substrates. We also create micro birdbath resonators by batch-level releasing the birdbath shells and demonstrate one of the best mechanical Q and low stiffness and damping anisotropies among existing micro mechanical resonators. The birdbath resonator is promising for emerging applications such as micro rate-integrating gyroscope (μ-RIG).