Fractal plasmonic metamaterials: physics and applications

We review our recent works on a particular type of metamaterials (MTMs), which are metallic plates drilled with periodic arrays of subwavelength apertures typically in fractal-like complex shapes. We first show that such MTMs can well mimic plasmonic metals in terms of surface plasmon properties, but with plasmon resonances solely dictated by their aperture geometries rather than the constitutional materials. We then develop an effective-medium description for such plasmonic MTMs based on the mode expansion theory. Based on these theoretical understandings, we show that such MTMs exhibit several interesting applications, such as superlensing, hyperlensing, and enhancing light-matter interactions, which are demonstrated by microwave experiments or full-wave simulations.