Optimization of surface high-order harmonic generation by tailoring nanostructures

Abstract

Many applications in attosecond science, lensless imaging, and industrial metrology need coherent extreme-ultraviolet pulses from high-order harmonic generation (HHG) in solids. However, the efficiency of the HHG plateau and the higher cutoff energy are nontrivial due to the limitation of the lower damage threshold of solids irradiated by laser fields. Here, we propose nanoengineered solid bowtie samples to overcome this limitation, which enables one to tailor the characteristic spacing between two nanotips. The near-field effect combined with recombined emissions with multiple scatterings can robustly increase conversion efficiencies and extend the cutoff energies of the HHG plateau. Our result paves the way to the manipulation of harmonic emissions in nanostructures and introduces imaging of the sub-cycle resolution of ultrafast electronic dynamics.