Nanoscale one-way-street for light

If light is able to propagate from left to right, the opposite direction is usually allowed as well. A beam of light can normally be sent back to its point of origin, just by reflecting it on a mirror. Researchers at TU Wien have developed a new device for breaking this rule. Just like in an electrical diode, which allows current to pass only in one direction, this glass fibre-based device transmits light only in one direction. The one-way-rule holds even if the pulse of light that passes throug...