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Novel plasmonic structures are on the rise, with applications varying from sensing and spectroscopy to solar cells and biological therapies. In this work, we introduce a plasmonic metasurface with a very rich dispersion spectrum, measured both experimentally and numerically. It shows a tunable absorption that depends on the folding angle and periodicity. A detailed numerical analysis identifies the presence of quasi-omnidirectional absorption. This broad directional absorption mode matches a Fabry–Perot resonance of a surface plasmon polariton along an elementary segment of the periodic structure. This geometry induced wide directional absorption is highly promising for a variety of photonic, light harvesting, and sensing applications.

We propose an efficient and versatile optimization scheme, based on the combination of multi-objective genetic algorithms and neural-networks, to reproduce specific colors through the optimization of the geometrical parameters of metal-dielectric diffraction gratings. To illustrate and assess the performance of this approach, we tailor the chromatic response of a structure composed of three adjacent hybrid V-groove diffraction gratings. To be close to the experimental situation, we include the feasibility constraints imposed by the fabrication process. The strength of our approach lies in the possibility to simultaneously optimize different contradictory objectives, avoiding time-consuming electromagnetic calculations.