  Surface nanoscale axial photonics (SNAP) structures are fabricated with a
femtosecond laser for the first time. The inscriptions introduced by the laser
pressurize the fiber and cause its nanoscale effective radius variation. We
demonstrate the subangstrom precise fabrication of individual and coupled SNAP
microresonators having the effective radius variation of several nanometers.
Our results pave the way to a novel ultraprecise SNAP fabrication technology
based on the femtosecond laser inscription.
