Exploring correlation, nondipole, and propagation time effects of high-order harmonic generation in solids.

We consider high-order harmonic generation (HHG) in solid and nanoscale systems. The significance of laser-induced correlation effects is studied with time-dependent density functional theory on a linear chain model of a generic band gap material [1,2]. Certain regimes are identified, where these effects may alter the harmonic yield by an order of magnitude. We give a guideline for identifying such regimes, as well as regimes where such effects are negligible.

The significance of (1) propagation time from the point of emission at the source to the point of detection, and (2) beyond-electric-dipole corrections to the light-matter interaction are investigated with the semiclassical model [3]. These effects inherit additional information regarding the dispersion of the material and can result in e.g., even-ordered harmonics from systems with space and time-inversion symmetry.