A technique is disclosed for utilizing direct-write electron-beam photolithography and holographic optical exposure to form gratings in optoelectronic structures. The direct-write e-beam process is used to form rectangular grating teeth in a mask substrate, where the mask is then used as a phase mask...http://www.google.ca/patents/US5413884?utm_source=gb-gplus-sharePatent US5413884 - Grating fabrication using electron beam lithography
