High-<inline-formula> <tex-math notation="LaTeX">$Q$ </tex-math></inline-formula> Si Microsphere Resonators Fabricated From Si-Cored Fibers for WGMs Excitation

Abstract

We demonstrated that silicon (Si) microsphere resonators, which exhibited high quality factor ( $Q$ ) whispering-gallery-modes (WGMs), could be rapidly fabricated from Si-cored fibers using CO2 laser reformation. WGMs were excited using the tapered silica fiber coupling technique, and a record resonant $Q$ as high as $4 \times 10^{\mathrm {\mathbf {5}}}$ was obtained from a Si microsphere with a diameter of $25.4~\mu \text{m}$ . The shift of resonant wavelength caused by thermooptic effect of Si material was also observed.