METHOD OF MANUFACTURE OF AN OPTICAL GRATING IN AN OPTICAL FIBRE

摘要

An optical grating is created within the core of an optical fibre by exposing the fibre to ultra-violet light of uniform intensity, but cyclically varying polarisation angle. The extent to which the incident light interacts with the fibre core to change its refractive index depends upon the relative alignment of the polarisation vector of the incident light and the fibre core, and thus only part of the uniform intensity of incident light causes a change in refractive index of the core. The periodicity of the variation in polarisation angle may be linear or non-linear; alternatively individual regions of varying refractive index may be created by exposing a single region of the fibre to a field of uv light with a varying polarisation angle, and then stepping the relative displacement of the incident light and the fibre to create further regions as desired.