Metasurfaces for engineering the dispersion and mode profile of guided waves

Metasurfaces can enable exotic phenomena in guided-wave structures when used as waveguide boundaries or when incorporated as elements perpendicular to the propagation direction. Here, we showcase the potential of metasurfaces for engineering the dispersion and mode profile of guided waves through two examples. The first concerns a multiresonant meta-surface that is designed to exhibit a purely quadratic spectral phase profile across a (fundamentally) arbitrarily-broad bandwidth. The proposed ultrathin metasurface can fit on a waveguide facet and interacts with the normally-incident electromagnetic field through a single pass. It can enable dispersion compensation and applications requiring control over the instantaneous frequency (chirp). The second example concerns a parallel-plate waveguide formed by metasurface boundaries which are both electrically and magnetically polarizable and support multiple resonances. They allow to shape the mode profile from concave, to flat, to convex and enable both superluminal and subluminal propagation, as well as both normal and anomalous group velocity dispersion. Our work highlights the potential of multiresonant metasurfaces for the advanced control of guided waves.