Merging Top‐Down and Bottom‐Up Approaches to Fabricate Artificial Photonic Nanomaterials with a Deterministic Electric and Magnetic Response

Artificial photonic nanomaterials made from densely packed scatterers are frequently realized either by top‐down or bottom‐up techniques. While top‐down techniques offer unprecedented control over achievable geometries for the scatterers, by trend they suffer from being limited to planar and periodic structures. In contrast, materials fabricated with bottom‐up techniques do not suffer from such disadvantages but, unfortunately, they offer only little control on achievable geometries for the scatterers. To overcome these limitations, a nanofabrication strategy is introduced that merges both approaches. A large number of scatterers are fabricated with a tailored optical response by fast character projection electron‐beam lithography and are embedded into a membrane. By peeling‐off this membrane from the substrate, scrambling, and densifying it, a bulk material comprising densely packed and randomly arranged scatterers is obtained. The fabrication of an isotropic material from these scatterers with a strong electric and magnetic response is demonstrated. The approach of this study unlocks novel opportunities to fabricate nanomaterials with a complex optical response in the bulk but also on top of arbitrarily shaped surfaces. The transformation of a subwavelength nanostructured metasurface with an electric and magnetic response to a photonic bulk material is investigated from morphological and optical perspectives. Departing from a periodic structure, a randomized orientation and arrangement of the meta‐atoms is forced that preserves their magnetic and electric response. The material combines the advantages of materials fabricated with both top‐down and bottom‐up techniques.