Sliding metasurfaces: a two-in-one meta-device for frequency filtering and beam steering.

Metasurfaces are considered the backbone of the ongoing photonics revolution to shape the electromagnetic waves on demand via a flat array of resonators. The beauty of metasurfaces lies in their ability to simultaneously control multiple waves. However, obtaining such multi-functionality often requires active components, such as active electronics and complex tuning mechanisms. A recent study demonstrates a fully passive architecture, composed of sliding metasurfaces that combines two distinct functionalities, i.e. frequency-selective filtering with wide-angle beam steering in a single platform. By replacing local phase reconfiguration with a simple geometric translation between complementary phase profiles, the work introduces a simple yet innovative route to a two-dimensional frequency-angle selection window. It opens new opportunities for passive wave-based information processing.