METHOD AND DEVICE FOR RECORDING A REFRACTIVE INDEX PATTERN IN AN OPTICAL MEDIUM

摘要

A device for recording a refractive index pattern in a photosensitive optical fibre consists of a rotary disc (3) formed with a phase mask in a circular pattern, which is rotated by an axis (11). The phase mask is illuminated with laser light in region (5) so that a moving interference pattern is formed. The optical fibre (1) is moved along a path in synchronism with the moving interference pattern so that the pattern becomes recorded in the fibre. The pattern can be formed continuously over long fibre lengths e.g. of the order of one metre.