Coherent Retroreflectors for Realization of Bound States in Waveguides

Metasurfaces provide very efficient tools to control electromagnetic waves in all frequency ranges. Unfortunately, their capabilities to control several waves simultaneously is very scarcely discussed in the literature. However, control of two coherent waves might provide additional functionalities to metasurfaces and can bring up new applications. In this talk, we present our recent results on single-sheet metasurfaces which act as retroreflectors when illuminated from both sides by two coherent plane waves. We call these sheets “coherent retroreflectors”. In particular, we discuss an application of these metasurfaces for realization of a bound state in a waveguide.