Millimeter-Sized Microfiber Coil Resonators With Enhanced Quality Factors by Increasing Coil Numbers

Microfiber coil resonators (MCRs) with quality factors as high as ~470 000 and small size (<; 2 mm³) were fabricated and characterized. Both simulated and experimental results showed that the average full-width at half-maximum of the resonant dips decreased with the number of rings, providing a proof of the dependence of increasing quality factor upon the number of rings, even when the gaps among adjacent rings were not strictly uniform. Compared to the previous reports, a multi-ring MCR can thus offer a new choice of obtaining a microfiber resonator with high quality factor.