Microoptical elements fabricated and replicated in semiconductor materials

Refractive microoptical elements were originally fabricated by mass-transport smoothing in gallium phosphide. Mass-transport smoothing is based on surface diffusion at elevated temperatures and allows the generation of highly efficient semiconductor microoptics. Starting from a master element, we have developed a replication technique for transferring microoptical surface reliefs into other semiconductor materials, such as gallium arsenide (GaAs). The technique uses a cast and dry etch process. Two different refractive microoptical elements have been replicated into GaAs, a Fresnel biprism and a concave micromirror. The elements have been characterized and show the high fidelity of the replication process.