Figure 1

(a) Model of the 2D non-Hermitian systems (infinitely long in the z direction) composed of cylindrical rods embedded vertically in water. Rods labeled L and G represent the loss and gain regions respectively. (b) Plane schematic diagram of a 2 × 1 super cell in the structure. (c) Band structure of 2D Hermitian PCs for a rectangular lattice with α = 0. The first Brillouin zone of the rectangular lattice is indicated in the inset. (d) Real part of the band structure in the non-Hermitian system for a rectangular lattice with α = 0.25.