Fabrication and Characterization of Fused Microfiber Resonators

We fabricate a 2.6-mm-diameter loop resonator from a tapered, step-index silica fiber of thickness ~7.2 mum. The resonator has a coupling region that is fused with a CO
₂
laser for reducing structural instabilities and improving the overall stability of the device. We experimentally demonstrate optical resonances with a Q-factor ges25 000 at a free-spectral range of 0.19 nm.