Design, Implementation, and Characterization of a Folded Spot-Array Generator for a Modulator-Based Free-Space Optical Interconnect

A folded structured light generator is presented. This spot generator is to be used in a modulator-based free-space optical interconnect. Three cascaded diffractive optical elements produce 4 x 8 clusters on an 800 um x 1600 um pitch, in which each cluster is a 4 x 4 array of 13.1- um-radius spots on a 90- um pitch. The folded configuration is more compact than an existing linear spot-array generator and replaces 14 optical surfaces with eight surfaces. Details of the optical design, sensitivity analysis, alignment techniques, assembly, and test results are presented.