Asymmetric transmission through diffraction-free optically linear metamaterials

We analyse the transmission of a linearly polarised plane-wave through a diffraction-free layered metamaterial stacked to another photonic crystal. The dispersion relation of the metamaterial at the resonant frequency allows for super-collimation of the incident light, while the photonic crystal introduces transverse momentum to excite a large number of diffraction orders. In various diffraction orders, light propagates in-phase internally in the structure, and except for the zero order is evanescent in the external area. A strong asymmetry in transmission is observed, making the structure a good candidate for an optical isolator.