Structure-insensitive zero refraction effect based on a two-dimensional annular photonic crystal

The zero refraction (ZR) effect based on a two-dimensional square lattice air-ring photonic crystal (PC) provides a powerful mean for beam steering. However, most previous studies have reported ZR performance mainly for transverse-magnetic polarization. This paper proposes a typical non-accidental triple degeneracy at Dirac-like point for transverse-electric polarization, which in case of the structure-insensitive parameters. As compared to conventional PCs, the proposed PC exhibits a totally different performance attributed to its robust structure, which greatly reduces the difficulty of processing technology.