Photonic crystal with 2-fold rotational symmetry for highly efficient asymmetric transmission

Abstract

Here we demonstrate a photonic crystal heterostructure with 2-fold rotational symmetry elliptical shape lattice for highly efficient optical asymmetric transmission based on the self-collimation effect. The forward transmitted light can be collimated along the propagation direction and efficiently coupled out of the structure. Thus, the high forward transmittance up to 0.661 and 0.581 at the telecommunication wavelength of 1550 nm for TE and TM polarized modes can be achieved by this design. The 2-fold rotational symmetry allows further optimizing the structure by tuning the angle between the major axis of the ellipse and the Γ-X direction, and found that high forward transmittance can be achieved when the major axis of the ellipse is along the Γ-X direction.