Rotationally variant grating writing in photonic crystal fibres

The role of rotational alignment during grating writing is comprehensively examined by the measurement of core luminescence from a Ge-doped 12 ring photonic crystal fibre,computer simulation of transmission and, definitively,by inscription of gratings at three angles– 0°, 30° and the optimum luminescent angle for this fibre, 21.5°. All experimental results were in accordance with each other and in agreement with simulation. Control of the rotational alignment of the fibre is demonstrably critical for reproducible grating writing.