METHOD AND DEVICE FOR PRODUCING A COUPLING GRATING FOR A WAVEGUIDE

摘要

The invention relates to a method and a device for producing a coupling grating (5) for a waveguide. The method relies on the technique of interference lithography, whereby an interference pattern on a light-sensitive layer (2) is exposed by superimposing two coherent light beams (3, 4) on said light-sensitive layer (2). Said pattern is then transferred onto the surface of the substrate (1) that lies underneath by subsequent developing and an etching process. The method is characterized in that it uses a shadow mask (6) that is mounted at minimum clearance relative to the surface of the light-sensitive layer (2). By observing said minimum clearance, the Fresnel diffraction images of both light beams (3, 4) are separated on the edge(7). The thickness of the light-sensitive layer (2) is selected in such a way that the superimposition of the Fresnel diffraction pattern of one light beam with the other undisturbed light beam suffices to uncover areas of the substrate (1) during subsequent developing of the layer (2). The method makes it possible to avoid transfer of unwanted diffraction effects on the edge of the shadow mask to the substrate. The method provides a cost-effective solution for the production of large-surface coupling grating matrices.