We report the fabrication of long-period optical fiber gratings by use of a
refractive-index increase induced by ion implantation. Helium ions were im
planted in an optical fiber core through a metal mask that had a 170-mu m-p
itch grating with spacing of 60 mu m. We obtained a wavelength-dependent ef
fective transmission loss by use of the grating. (C) 2000 Optical Society o
f America. OCIS codes: 060.0060, 220.4000, 230.1480, 160.6030, 230.0230, 35
0.2770.