High-Harmonic Generation Using a Single Dielectric Nanostructure

Abstract

High-harmonic generation (HHG) from solids is a novel method used to emanate coherent extreme-ultraviolet (EUV) pulses. The efficiency of plasmonic HHG can be improved by enhancing the field of nanostructures. However, the nanostructures used for plasmonic HHG have a limitation owing to the damage caused by the amplified field. This study presents a single conical sapphire nanostructure used as a compact HHG emitter that generates high-order harmonics with wavelengths up to approximately 60 nm without causing severe damage. We compare the structure with a gold-layered conical sapphire structure and a bulk sapphire. The conical sapphire structure has a higher damage threshold and reusability for EUV generation even though it has a lower HHG intensity than that of the gold-layered conical sapphire structure because of the lower intensity enhancement. The measured signal intensity of the high-order harmonics in the EUV band from the conical sapphire structure is ten times higher than that of the bulk sapphire. The results confirm the possibility of creating a compact EUV light source for nanoscale applications.