Enhanced High Harmonic and Terahertz Generation from LiNbO3 Metasurface

All-dielectric metasurfaces exhibit high damage thresholds and strong enhancement of the driving field, making them attractive platforms to control the high-field processes at the nanoscale. Here we report enhanced non-perturbative high-harmonic and terahertz emission from a LiNbO3 metasurface. The harmonic and terahertz intensity are enhanced by more than one order of magnitude compared to unpatterned samples. The enhanced high harmonics and terahertz waves are highly anisotropic with respect to the excitation polarization and are selective by the excitation wavelength due to its resonant features.