FIB lithography of nanoporous gold slits for extraordinary transmission

► We performed dealloying of Ag-Au alloy films in order to get nanoporous gold layers. ► Nanoporous gold nanoslits were FIB milled with different techniques. ► Nanoporous gold nanoslits have been optically characterized in zero-order transmission. ► The plasmonic response of different samples has been analyzed. ► The optical response has been related to the porous structure and milling technique.