Authors: Giuseppe Emanuele Lio, Antonio Ferraro, Tiziana Ritacco, Dante Maria Aceti, Antonio De Luca, Michele Giocondo, Roberto Caputo

Advanced Materials 2021, 2008644
DOI:  https://doi.org/10.1002/adma.202008644

Abstract: A novel technique is developed to improve the resolution of two‐photon direct laser writing lithography. Thanks to the high collimation enabled by extraordinary εNZ (near‐zero) metamaterial features, ultrathin dielectric hyper‐resolute nanostructures are within reach. With respect to the standard direct laser writing approach, a size reduction of 89% and 50%, in height and width respectively, is achieved with the height of the structures adjustable between 5 and 50 nm. The retrieved 2D fabrication parameters are exploited for realizing extremely thin all‐dielectric metalenses tailored through deep machine learning codes. The hyper‐resolution achieved in the writing process enables the fabrication of a highly detailed dielectric 3D bas‐relief (with full height of 500 nm) of Da Vinci's “Lady with an Ermine”. The proof‐of‐concept results show intriguing cues for the current and trendsetting research scenario in anti‐counterfeiting applications and ultracompact photonics, paving the way for the realization of all‐dielectric and apochromatic ultrathin imaging systems.

Image caption:Leonardo Da Vinci, Lady with an Ermine