High harmonic generation (HHG) is a highly non-linear phenomenon where a system (for example, an atom) absorbs many photons of a laser and emits photons of much higher energy, whose frequency is a ...

Nonlinear optics is a branch of optics that deals with the complex nonlinear relationships between the optical response of the medium and the incident light when it interacts with the optical medium.

High-order harmonic generation (HHG) — a technique that converts light into much higher frequencies — is an essential tool for exploring otherwise inaccessible parts of the electromagnetic spectrum.

Figure 1 Schematic diagram of a nonlinear metasurface composed of asymmetric meta-atoms based on guided mode resonance and bound states in the continuum. Nonlinear optics is a branch of optics that ...