Grating formation in a germanium free silicon oxynitride fibre

For the first time, Bragg gratings have been written in a germanium-free nitrogen-doped-silica-core fibre. Index changes as high as 8.4 × 10–4 have been achieved in the gratings under exposure to 193 nm light without hydrogen loading. The grating growth dynamics is similar to that in heavily doped germanosilicate fibres.