Design of single-phase chiral metamaterials for broadband double negativity via shape optimization

Double negative elastic metamaterials are a kind of novel artificial materials with unique ability to manipulate wave propagation in the subwavelength scale. They generally designed by inducing combination multiple resonance different effective parameters. However, due limitation empirical structural shape and design tools, these made complex multiphase but possess relatively narrow frequency range double negativity, which is unsuitable for practical engineering applications. In this work, optimization single-phase chiral (EMMs) based strategy presented designing EMMs broadband negativity (negative mass density bulk modulus). Several numerical examples validate method considering initial shapes, target ranges variables. Besides, simulations related including refraction imaging investigated using optimized EMMs. Interestingly, mode conversion super-resolution 0.28? observed. The proposed metamaterial combined approach very efficient way obtain over broad band it may thus have great potential new metamaterials.