Fabrication of long-period optical fiber gratings by use of ion implantation

We report the fabrication of long-period optical fiber gratings by use of a refractive-index increase induced by ion implantation. Helium ions were implanted in an optical fiber core through a metal mask that had a 170‐µm-pitch grating with spacing of 60 µm. We obtained a wavelength-dependent effective transmission loss by use of the grating.