Two-Dimension Asymmetric Electromagnetically Induced Grating in Rydberg Atoms

We investigate the realization and manipulation of a two-dimension (2D), asymmetric, electromagnetically induced grating (EIG) in a sample of Rydberg atoms exhibiting the van der Waals (vdW) interactions. The scheme relies on the application of a strong control field and a weak probe field, with the former periodically modulated in a 2D plane and the latter incident perpendicular to the 2D plane. We find that the probe field can be diffracted into an asymmetric intensity distribution depending on the relevant modulation parameters of the control field, as well as the density and length of the atomic sample. In particular, higher-order diffraction intensities can be enhanced in different ways as the vdW interaction, modulation strength, or sample length is increased. It is also of interest that the asymmetric diffraction distribution can be shifted to different quadrants by choosing appropriate modulation phases of the control field. These results may be used to develop new photonic devices with asymmetric diffraction properties required in future all-optical networks.