Bragg gratings in standard and microstructured all-silica fibres inscribed using ultra-fast ultraviolet radiation

The inscription of Bragg reflectors in commercial, all-silica standard and microstructured optical fibres using picosecond and femtosecond 248 nm laser radiation, will be presented. The research results reported herein aim to the investigation of the optimum photosensitivity regime and index engineering route, and its dependence upon the wavelength and intensity of the laser source, for the high yield inscription of Bragg reflectors in all-silica standard and microstructured optical fibres. The ultraviolet laser source used was a 248 nm, 5 ps / 500 fs hybrid dye / excimer; while hydrogenated and pristine fluorine doped standard Sumitomo Z-fibre, Blazephotonics ESM-12 and Crystal Fiber LMA-10 microstructured optical fibres were exposed. Refractive index evolution curves for both average and modulated index changes, as well as, thermal annealing results are presented and discussed. A novel interferometer design will be presented for the high yield and efficiency inscription of strong Bragg reflectors in all-silica fibres using femtosecond laser radiation.