Apodisation of the spectral response of fibre Bragg gratings using a phase mask with variable diffraction efficiency

Abstract
Bragg gratings with sidelobe levels 26 dB lower than the peak reflectivity have been fabricated in standard telecommunication optical fibres by exposure to ultraviolet light through a phase mask with a locally varying diffraction efficiency. This represents a reduction of 14 dB in the sidelobe levels compared to uniform gratings with the same bandwidth and reflectivity.