Optoelectronic interconnects with high packing densities

Optical board-to-board interconnections are presented. A typically some 5-10 mm thick light-guiding plate is used for confinement and transport of the optical signals. The plate is equipped with grating couplers fabricated as volume phase holograms in dichromated gelatin. The apertures of the optoelectronic transmitters are imaged onto the apertures of the receivers by aspheric field lenses or mirrors mounted on the plate. Such optical systems render packing densities up to 1000 channels/cm² possible that are required for the application of densely packed integrated arrays of semiconductor lasers and detectors. Grating dispersion, axial astigmatism, geometrical distortion and coma are eliminated in the proposed optical setup. Results from ray tracing and experiment are presented