Abstract: An improved technique of exposing a photoresist through a grating mask reduces the occurrence of overlapping gratings and also avoids distortions in the exposed mask when there is a gap between the contact mask and the photoresist layer. The technique is particularly well suited to forming Bragg gratings on semiconductors and other materials that are used for wavelength selection in, for example, optical communications applications. The technique employs a phase grating held close to, but out of contact with, the photoresist layer. Amongst the advantages provided by the present invention is that the requirements of the permissible thickness of the photoresist layer suitable for writing high visibility gratings are relaxed, thus reducing the complexity and costs for processing the substrate.

Abstract: In a method of making a replication tool, replication parts for both two dimensional optical elements, such as are fabricated using micro-forming techniques, and three dimensional optical elements, that are typically formed using cutting techniques are present on the replication tool. A method of manufacturing a replication tool for a planar optical sheet includes mounting at least one optical element part on a base to form a master part and forming a conductive metal layer over the master part. The method also comprises electrochemically depositing over the conductive metal layer to form an electrochemically deposited layer, separating the electrochemically deposited layer from the master part. The invention also relates to the replication tool itself and optical circuits formed using the replication tool.