The trouble with pesky Photon, at least as far as ultra-fast optical computing is concerned, is that he keeps coming back. If a data-carrying beam of light collides with reflections bouncing around between the components of a chip, it can suffer enough interference to make people yearn for the good old days of electrons. What's needed is the optical equivalent of a diode, which only allows light to pass one way, and that's exactly what researchers at Caltech and the University of California claim to have devel
