Rainbow Trapping with Long Oscillation Lifetimes in Gradient Magnetoinductive Metasurfaces

In ``rainbow trapping'', waves of different wavelengths are spatially separated, which is interesting for $e.g.$ optical buffers, multiplexers, and energy harvesting. It is difficult to realize such trapping without reflections, though. Unlike previous designs, this study proposes a hybrid metamaterial--transmission-line structure with gradient resonant channels to trap waves with a long oscillation lifetime, enhancing wave-structure interaction. The trapped energy can be absorbed perfectly via the inherent losses of the materials. This phenomenon could be exploited in designs for mechanical waves as well.