Fabrication of optical waveguides by 2 MeV Ar + irradiation of germanium-doped flame-hydrolysis deposited silica

In this paper, the effects of irradiation of Ge-doped FHD silica with 2 MeV Ar + ions were optically characterized using an m-line technique based on grating couplers. An increase of refractive index as high as 1.2 × 10 −2 was obtained, larger than the values normally reported for UV or electron-beam irradiation of the same material (typically of ≈10 −3). Thermal annealing has been carried out and an activation energy of 0.36 eV for the recovery of the refractive index has been estimated, suggesting that a bond rearrangement mechanism could be responsible for the change in refractive index.