Anomalous transmission of disordered photonic graphenes at the Dirac point

The transmission properties of disordered photonic graphenes are investigated in microwave experiments. In the weak-localization regime, we found that, in the passbands the transmission decreases as the random degree increases, owing to the enhanced coherent backscattering effect. However, at the Dirac point, with the increase of the random degree, the transmission increases rather than decreasing. This observed anomalous transportation, also called weak antilocalization, provides the important experimental clue that the Berry phase associated with the Dirac point may suppress the coherent backscattering effect in a random system. Copyright (c) EPLA, 2013