High harmonic generation assisted by the field enhancement near rough metallic surface

High harmonic generation (HHG) has been extensively studied in the last decade due to its potential for various applications. Recently demonstrated HHG in the vicinity of bowtie nanoantennae utilizes the high field enhancement provided by metal nanostructures due to excitation of plasmonic resonances, which made it possible to achieve HHG at MHz repetition rates with very low pump intensities. Rough metallic surface can provide significant field enhancement and are known to yield a dramatic increase of the efficiency of nonlinear processes such as Raman scattering. Such surface is easily manufactured and can serve as a promising system for HHG at megahertz repetition rates. In this contribution, we develop a theory of the high harmonic generation in the vicinity of the rough metallic surface.