The present invention entails a phase mask for producing a plurality of volume gratings for use as optical couplers and method for creating the phase mask. The phase mask is produced by creating a plurality of volume gratings having predetermined characteristics which allow the phase mask, when excited...http://www.google.com/patents/US6606432?utm_source=gb-gplus-sharePatent US6606432 - Phase mask consisting of an array of multiple diffractive elements for simultaneous accurate fabrication of large arrays of optical couplers and method for making same
