Depolarization via Coherently Activated Plasmonic Metasurfaces

Precise control over the shapes and sizes of metallic nanoantennas (meta-atoms) in plasmonic metasurfaces has made them promising candidates for a wide range of applications, from optical devices to encryption and information processing. In this article, we investigate the coherent control of depolarization in the in-plane scattering of metasurfaces composed of unit cells ranging from flat Au nanoantennas to regions densely packed with randomly shaped and sized Au nanoislands. We demonstrate that when the nanoisland regions interact with light, they evolve into “coherent” domains through surface lattice resonances, forming coherently activated metasurfaces. Our analysis of the Stokes parameters of in-plane scattering reveals that such metasurfaces exhibit strong scattering with distinct depolarization characteristics, including the formation of zero degree-of-polarization states. We show that as the nanoislands grow larger and coalesce into highly flat nanoantennas, significant intensity and depolarization redistribution occur, fundamentally altering the in-plane scattering behavior and polarization properties. The results highlight the profound application of polarization analysis for tracing details of coherent processes and the potential of metasurfaces that leverage coherent engineering of plasmonic modes.