Scientists see the one-way light

Science News : A beam of light shining on the left side of a normal piece of glass or plastic will pass through and reflect exactly the same as a beam of light shining on the right side. Nonlinear materials interact with light in a very different way; light changes the properties of such materials as it passes through them, and those changes affect the behavior of the light itself. As a result, the frequency of light that can pass through those materials depends on the direction of the light. Giulio Casati, of the University of Insubria in Como, Italy, and Stefani Lepri, of the Italian National Research Council for Complex Systems in Florence, mathematically modeled the behavior of light passing through two layers of such material and described a way to transmit about 80% of the light traveling in one direction while blocking about 70% of the light coming from the opposite direction. This selectivity could be used in the creation of wave diodes. Traditional diodes allow electric current to flow in one direction, and a wave diode could allow light to flow in one direction in quantum or optical computer applications. The model may also apply to acoustical applications of nonlinear materials.