Two-dimensional arrays of diffractive microlenses for optical interconnects

Arrays of 16×16 diffractive optical microlenses are presented that are used in free space interconnection networks of electronic switching stages. They have been fabricated as `binary optical elements´ in glass substrates by microstructuring techniques. Individual elements have a diameter of 2 mm and 200 μm and 16 levels per zone. Arrays with different F-number lenses for the two wavelengths 1.52 μm and 0.63 μm have been fabricated. In order to reduce reflection losses and cross talk in an interconnection network the lens arrays have been AR-coated with a two layer system of TiO₂ and SiO₂. The measured diffraction efficiency of the lenses with large F-numbers is 95%