Dynamic fabrication method of SNAP microresonators

Surface nanoscale axial photonics (SNAP) technology has demonstrated the record subangstrom fabrication precision of optical microresonators and resonant photonic circuits at the optical fiber surface. However, fabrication errors arising from fluctuations of temperature, inscription parameters, alignment inconsistencies, and other factors did not allow researchers to achieve the subangstrom precision without sophisticated post-processing. Here, we show that the key fabrication method of SNAP structures-CO₂ laser beam optical fiber annealing-suffers from significant fiber displacements, which may introduce a few percent fabrication errors. To suppress the effects of misalignment, we develop a dynamic fabrication method employing a translating beam exposure and demonstrate its excellent precision. An effective fiber radius variation of ∼10 nm is introduced with an error of ∼0.1 Å. We suggest that the remaining fabrication errors can be attributed to laser power fluctuations.