Fabrication of high-Q, millimeter-scale microbubble resonators

We present, to our knowledge, a novel method for fabricating symmetric microbubble resonators (MBRs) using a CO₂ laser combined with an automated rotational system, eliminating the need for pre-tapered capillary tubes. This approach enables uniform heat distribution around the capillary, allowing the production of MBRs with diameters ranging from micrometers to millimeters. The fabrication system is designed with readily available off-the-shelf components, making it easy to set up and reproduce without specialized equipment. By precisely controlling internal pressure in the tube and laser power, we achieved efficient expansion with smooth surfaces and high structural integrity. The fabricated MBRs exhibited Q-factors exceeding 10⁷, demonstrating their potential for high-performance sensing applications. Additionally, their compatibility with standard components facilitates seamless integration into microfluidic systems, expanding the potential for diverse applications.