Lithography-free fabrication of extraordinary transmission plasmonic metasurfaces over large areas employing ultrafast lasers

Plasmonic metasurfaces based on the extraordinary optical transmission effect (EOT) can be deliberately designed to efficiently transmit specific spectral bands from the visible to the long-infrared regimes, but can also provide high electric field confinement in regions much smaller than the operation wavelength [1] . Such nano/microphotonic devices (which, as shown in Fig. 1(a) , consist of subwavelength periodically or randomly arranged apertures on ultrathin metallic films) could therefore find applications in important technological fields such as compact multispectral imaging, biosensing, transmissive colour displays, non-linear optics or enhancement of the Raman signal. However, due to their subwavelength nature, fabrication of EOT metasurfaces operating in the visible and infrared spectral regimes is typically conducted through expensive, micro- and nanofabrication techniques carried out in strict cleanroom environments. Therefore, patterning of large areas required for applications currently dominated by conventional optical elements are translated into several fabrication steps and long lithography writing times: procedures that significantly increase the operation cost and energy consumption to a non-acceptable level for most industrial entities.