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 developed. As you'll see in the photo after the break, their metallic-silicon optical waveguide allows light to travel smoothly from left to right, but it breaks up and dissipates any photons traveling in the opposite direction. This is all good, because there's no point having futuristic 50Gbps optical interconnects if our CPUs lag behind. Light up the source link for a fuller explanation.