IMAGED APERTURE MASK GRATING WRITING

摘要

A method is disclosed of writing a grating in a photosensitive waveguide comprising the steps of: (a) projecting photosensitive light in a first direction through a mask (3) having a series of spaced apart opaque lines; (b) focusing the light after it has passed through the mask down to a focal point (5); and (c) placing the photosensitive waveguide (7, 8) in the region adjacent said focal point to image the mask in the photosensitive waveguide to thereby induce refractive index changes in regions of the photosensitive waveguide exposed to the light to write said grating.