We have developed an ab-initio multi-scale simulation for the
generation of solid-state high harmonics self-consistently. We combine
the microscopic non-linear response treated within the frameworks of
TDDFT or multiband Bloch equations with mesoscopic propagation and
source distribution effects providing novel insights in HHG in solids.
Microscopic simulation of the non-linear response of a single cell of
the periodic system alone fails to yield a well-defined harmonic
spectrum irrespective of the level of the underlying approximation.
We find the spatio-temporal distribution of the emission events on the
mesoscopic scale to lead to the formation of a clean high-harmonic
spectrum with pronounced peaks at odd harmonics by way of