Coupled high Q-factor Surface Nanoscale Axial Photonics (SNAP) microresonators

We experimentally demonstrate series of identical two, three, and five coupled high Q-factor Surface Nanoscale Axial Photonics (SNAP) microresonators formed by periodic nanoscale variation of the optical fiber radius. These microresonators are fabricated with a 100 \mum period along an 18 \mum radius optical fiber. The axial FWHM of these microresonators is 80 \mum and their Q-factor exceeds 107. In addition, we demonstrate a SNAP microresonator with the axial FWHM as small as 30 \mum and the axial FWHM of the fundamental mode as small as 10 \mum. These results may potentially enable the dense integration of record low loss coupled photonic microdevices on the optical fiber platform.