Non-reciprocal beam behavior in two-dimensional photonic crystal slab

We simulate Gaussian beam propagation in two-dimensional photonic crystal slab (PCS). The found results show that character of beam propagation depends on the refractive index modulation on PCS boundaries. We observe a non-reciprocal beam behavior for PCS with different modulations on the boundaries. The non-reciprocity reaches its maximum at maximum of the refractive index modulation on the one boundary and minimum one on another boundary.