Ultrahigh Angular Selectivity of Disorder-Engineered Metasurfaces

Metastructures hold promises for the realization of novel optical functions. Common topologies utilized in the form of metasurfaces featuring simple periodicities, however, are not exploiting the full potential such platform can offer. On the other hand, disordered metasurfaces consisting of strongly coupled elements can provide a versatile platform with large degrees of freedom to be exploited in an inverse design process. Here, we investigate a new class of disordered metasurfaces; a disordered network of scattering elements strongly connected through interelement free space coupling and excited guided waves. Such a highly connected network of scatterers exhibits very strong angular sensitivity for the plane waves illuminating the structure at arbitrary angles; a minute deviation in the angle of incidence results in a drastic change in the radiation profile both in near and far-field regions. This peculiar feature is harnessed by engineered disorder implemented through a rigorous near-optimal freeform inverse design algorithm to realize arbitrarily large metasurfaces with unexpected angular single/multifunctionality. Our proposed scheme is extendable to implement novel functions demanded by emerging applications such as LiDARs and highly secure communication systems.