Steep skirt fibre Bragg grating fabrication using a new apodised phase mask

Dense WDM systems demand fibre Bragg gratings (FBG) with low sidelobes and a sharp spectral skirt. A new apodised phase mask is reported here for efficiently suppressing sidelobes in FBG production. A 20 dB sidelobe reduction, measured by both an OSA and a tunable laser scanning technique, was achieved. The skirt steepness, which is a ratio of the FBG reflection bandwidth at -25 dB to the bandwidth at -0.5 dB, was demonstrated to be 1.85. The FBGs are suitable for dense WDM with a channel spacing of <0.8 nm