Novel writing technique of long and highly reflective in-fibre gratings

A novel method for writing fibre Bragg gratings is introduced. The method consists of translating a UV beam along the fibre through a phase mask. Because the phase mask and the fibre are held together, the phase of the interference pattern generated by the mask is not altered when the beam is translated along the mask. Gratings up to 1.5 cm long, limited by the mask dimensions, and with 98.5% reflection have been written in that way