A Spatial Beam Splitter Consisting of a Near-Zero Refractive Index Medium

A novel metamaterial-based beam splitter is demonstrated in this communication. The metamaterial is a three-dimensional (3 D) fishnet structure arranged in a two-dimensional (2 D) square lattice. According to Snell´s law, the refracted wave from medium into air tends to be normal to the interface if the effective refractive index of medium is approximately zero. In light of this concept, the study presents a metamaterial with near-zero effective refractive index and an internal line source inside as excitation. Metallic flares with specific tilting angle were installed at four sides of the beam splitter to reduce reflection coefficient and match the impedance of the fishnet structure and free space. In addition to calculating the phase relation of eigenwaves in the metamaterial, this study measures the radiation patterns to verify its spatially beam-splitting characteristics.