Replication techniques for diffractive optical elements

Replication technologies such as embossing, moulding and casting are highly attractive for the fabrication of surface relief Diffractive Optical Element (DOE) microstructures. They have very high resolution, typically in the nanometer range, and allow the fabrication of large area, complex microstructure by low-cost, high volume industrial production processes. Their use is already well established for gratings, holograms and diffractive foil, and the extension to the fabrication of deeper and higher aspect ratio microstructure is underway. The combination of replication technology with other processes such as dry etching and thin film coating can also offer new possibilities in the design of DOEs suitable for mass-production. Replication is expected to become a key technology for the microfabrication of DOEs in the future. This paper reviews the major DOE replication techniques and describes recent work and results.