Femtosecond laser writing Bragg gratings in pure silica photonic crystal fibres

The fabrication of Bragg gratings in pure silica photonic crystal fibres using ultra-violet femtosecond laser radiation at 267 nm is reported. Gratings have been fabricated with a depth of up to 10 dB and an average index change of Delta n > 4 x 10(-4). Thermal annealing investigations indicate that our grating type is not type II.