Design for quality: reconfigurable flat optics based on active metasurfaces

TLDR

Optical metasurfaces are planar subwavelength nanoantenna arrays that can sculpt wavefronts arbitrarily, and active metasurfaces add dynamic tunability, but designing reconfigurable optics requires optimizing optical quality across multiple states. The article reviews design principles and algorithms for active meta‑optics across scales from single meta‑atoms to full devices. These design approaches are illustrated with examples of reconfigurable metasurfaces that employ optical phase‑change materials.

Abstract

Abstract Optical metasurfaces, planar subwavelength nanoantenna arrays with the singular ability to sculpt wavefront in almost arbitrary manners, are poised to become a powerful tool enabling compact and high-performance optics with novel functionalities. A particularly intriguing research direction within this field is active metasurfaces, whose optical response can be dynamically tuned postfabrication, thus allowing a plurality of applications unattainable with traditional bulk optics. Designing reconfigurable optics based on active metasurfaces is, however, presented with a unique challenge, since the optical quality of the devices must be optimized at multiple optical states. In this article, we provide a critical review on the active meta-optics design principles and algorithms that are applied across structural hierarchies ranging from single meta-atoms to full meta-optical devices. The discussed approaches are illustrated by specific examples of reconfigurable metasurfaces based on optical phase-change materials.