  Recently introduced Surface Nanoscale Axial Photonics (SNAP) makes it
possible to fabricate high Q-factor microresonators and other photonic
microdevices by dramatically small deformation of the optical fiber surface. To
become a practical and robust technology, the SNAP platform requires methods
enabling reproducible modification of the optical fiber radius at nanoscale. In
this Letter, we demonstrate super-accurate fabrication of high Q-factor
microresonators by nanoscale modification of the optical fiber radius and
refractive index using the CO2 laser and the UV excimer laser beam exposures.
The achieved fabrication accuracy is better than 2 angstroms in variation of
the effective fiber radius.
