Free-space systems and devices

The optical hardware required for photonic switching systems based on free-space digital optics is reviewed. Free-space digital optics offers the opportunity for new advances in switching fabrics through the exploitation of the connections available using optical pin-outs. It is pointed out that there has been significant progress in the development of the optical hardware required to (1) combine multiple inputs through the same aperture onto the optical window of an optical logic device, or the detector, modulator, laser, or LED (light-emitting diode) used as an optical pin-out on a 2D-OEIC (optoelectronic integrated circuit), (2) implement low-loss free-space optical interconnects, and (3) generate the spot arrays of uniform intensity required for the optical power supplies