Broadband subwavelength imaging using non-resonant metamaterials

Previous subwavelength imaging using hyperlens is based on negative constitutive parameters that are realized by strongly dispersive materials and work only in a narrow frequency band. Here, we demonstrated that subwavelength imaging can be achieved in a broad frequency band using non-resonant magnetic metamaterials. The metamaterial shows an elliptical dispersion relation and can be fabricated by metallic closed-rings with a broadband magnetic response. With this elliptically dispersive material, most of the evanescent waves with high-k modes can be converted to propagating modes and the subwavelength information is reconstructed. Both simulation and experiment results show that this kind of metalens can achieve a broadband subwavelength imaging effect.