Unidirectional transmission using non-symmetric photonic-crystal gratings made of isotropic materials

Unidirectional transmission can be obtained in non-symmetric photonic-crystal gratings at a fixed angle of incidence due to combination of the peculiar dispersion and the properly introduced corrugations. In the simplest way, the latter can be obtained by removing every second rod from one of the interface layers. Two main regimes are distinguished, depending on the angle of incidence and number of the beams involved to the transmission. Adjusting the lattice parameters, one can realize the situation when more than 80 percent of the incident plane-wave energy is transmitted in one direction, while transmission in the opposite direction is vanishing.