Faraday Waves in Highly Nonlocal Nonlinear Metasurfaces

ABSTRACT Metasurfaces composed of thin, densely packed planar arrays of resonant subwavelength elements are central to emerging photonic technologies operating beyond the diffraction limit. While their steady‐state functionalities are well‐documented, the potential for complex, high‐speed temporal control remains largely untapped. Here, we bridge this gap by investigating the spatiotemporal nonlinear dynamics of a metasurface consisting of a two‐dimensional array of nonlinear meta‐atoms. We formulate a general theoretical model to describe the nonlinear dynamical behavior of such systems and demonstrate that the interplay between the nonlinear resonant response of individual elements and strong dipole–dipole coupling triggers a modulation instability. This instability gives rise to long‐lived Faraday waves in the form of flat, beaded, and breaking stripes, as well as chaotic‐like patterns. We find that these patterns emerge and reconfigure on timescales as short as fs. Our results suggest that Faraday‐wave dynamics can serve as a physical foundation for petahertz‐scale all‐optical processors, programmable light routing, and ultrafast optical neural networks, enabling complex signal processing at the fundamental limits of light‐matter interaction.