Metasurfaces are planar arrangements of resonant nano-objects carefully designed to shape an incident wavefront. This seminar will offer an overview of the basics and key applications of disordered optical metasurfaces [1] -- a specific class of nanostructured surface harnessing nanoscale optical resonances and multiple scattering for controlling light diffusion. As we will see, complexity offers many degrees of freedom to control the optical properties of surfaces, but also poses some challenges in theoretical and numerical modelling. Particular attention will be given to the relation between nanostructure parameters and the so-called "bidirectional scattering distribution function", which describes the optical response of a surface to an arbitrary illumination. Eventually, we will see how disordered optical metasurfaces can be used to create impressive visual effects at the macroscale thanks to coherent phenomena at the nanoscale [2] -- a result that may yield new opportunities in several branches of visual arts.
[1] P. Lalanne, M. Chen, C. Rockstuhl, A. Sprafke, A. Dmitriev, and K. Vynck, Adv. Opt. Photon. 17, 45-112 (2025).
[2] K. Vynck, R. Pacanowski, A. Agreda, A. Dufay, X. Granier, and P. Lalanne, Nat. Mater. 21, 1035-1041 (2022).
