Metasurfaces contain structured matter at the subwavength scale which allow unprecedented optical properties and functionalities compared to naturally occurring materials. One emerging technology in this field has been nonlinear optics which use ultrathin planarized devices that can generate higher harmonic frequencies while simultaneously imparting a locally tailored, spatially dependent engineered amplitude and phase on the generated wavefront. To date, most metasurfaces have relied on localized nanoscale resonances, however, more recently, nonlocal wave-matter interactions have been demonstrated. But, so far these have been limited to the linear regime. Recently, new work has demonstrated that it is possible to tailor the local optical properties of a nonlinear metasurface that relies on nonlocal, lattice supported phenomena.
This new work was reported by Michele Cotrufo, Luca Carletti, Adam Overvig, and Andrea Alù in a collaborative effort from Advanced Science Research Center, GC/CUNY, The City University of New York, The Institute of Optics at the University of Rochester, University of Brescia, Italy, National Institute of Optics, Italy, and Stevens Institute of Technology.
The work was performed in part using an STS-Elionix ELS 50kV electron beam lithography system at the Advanced Science Research Center, GC/CUNY facility.
For more information see https://doi.org/10.1186/s43593-025-00116-7.
Image: Scanning electron micrograph of the fabricated amorphous silicon nonlocal metasurface (scale bar = 2 μm) on a glass substrate. The two insets show zoomed-in views of the super unit-cell (blue-edged rectangle) with dimensions ax = 7.12 μm and ay = 0.89 μm, and of the unit-cell (red-edged rectangle) with dimensions A = 0.445 μm and 2A. The dimensions of the two apertures in the red-edged unit cell are 126 nm by 371 nm. (Image use is made available under the terms of the Creative Commons Attribution 4.0 International License.)