The fabrication of eight-level reflective phase gratings in Si by electron-beam lithography and reactive ion etching, and focused ion-beam milling, has been investigated. Electron-beam lithography and reactive ion etching were used to fabricate gratings with 0.5-μm feature sizes. Alignment of successive levels was held to 50 nm by careful control of proximity effects. Focused ion-beam milling was used to fabricate continuously blazed surface reliefs. The effects of binary and continuously blazed surface reliefs on the first-order diffraction efficiency were determined. Eight-level binary reliefs produced efficiencies of 75% and were limited by phase errors while continuously blazed reliefs produced efficiencies of 90%.

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Optical interconnects are being used increasingly in military systems. Sensor platforms in particular have seen great benefit from the use of fiberoptics as a replacement for coaxial cables. Optical interconnects is continuing to find new application at shorter and shorter distances throughout the sensor platform. High density free space optical components will extend the use of optical interconnects down to the inter-chip level. However, optical interconnect technologies can do more than just transmit data at high speeds. The ability to simultaneously process and transmit optical data, as could be done in optical signal processing, gives optical interconnects the ability to inject new capabilities into sensor system on-board processing. In order to see actual field deployment, these new technologies will need to be rigorously tested.