Moire phase masks for automatic pure apodisation of fibre Bragg gratings

Abstract

A Moire technique is used in the fabrication of a diffractive phase mask by electron beam lithography. The phase mask has a varying diffraction efficiency designed to produce apodised fibre Bragg gratingswith a uniform ultraviolet beam exposure. Since the illumination is uniform, the average induced refractive index is constant along the grating and pure apodisation results