All-optical control of high-order harmonic generation in correlated systems

Solid-state high-order harmonic generation (HHG) presents a promising approach for achieving controllable broadband coherent light sources and dynamically detecting materials. In this study, we demonstrate the all-optical control of HHG in a strongly correlated system, vanadium dioxide ( VO 2 ), through photo-carrier doping. It has been discovered that HHG can be efficiently modified using a pump laser, achieving modulation depths approaching 100% (extinction ratio ≥40 dB ) on femtosecond timescales. Quantitative analysis reveals that the driving forces behind pump-dependent HHG are attributed to two distinct many-body dynamics: the scattering-induced dephasing and the insulator-to-metal transition (IMT) caused by photo-induced electron shielding. These two dynamics play a crucial role in defining the intensity and transient response of the HHG. Furthermore, we demonstrate that it is possible to quantitatively extract the metallic phase fraction from time-resolved HHG (tr-HHG) signals throughout the IMT. This study highlights the benefits of utilizing many-body dynamics for controlling HHG and underscores the necessity for further theoretical research on HHG in strongly correlated systems.