Achromatic fan-out diffractive system for white-light free-space optical interconnects

A simple and versatile white-light fan-out diffractive system based on the achromatization of the fractional Talbot effect is proposed. This achromati c configuration is able to interconnect a single polychromatic point source with a 2-D array of optoelectronic microdevices with low residual chromati c aberration even for white light. The whole broadband beamsplitter system is formed by two simple diffractive optical elements, a periodic diffractiv e lenslet array and a diffractive lens, that are made with a direct laser w riting technique giving high light efficiency. The focal amplitude distribu tion corresponding to the lenslet array produces, by free-space propagation , self-replicas with different density of light points. These patterns, in conjunction with the achromatization process carried out by the additional diffractive lens, are, in short, the key to achieving a set of undistorted white-light spots at the output plane with high uniformity and variable sep aration between them. Experimental results are also shown.