Title: Insight into High-order Harmonic Generation from Solids: The Contributions of the Bloch Wave-packets Moving on the Group and Phase Velocities,
Abstract: We study numerically the Bloch electron wavepacket dynamics in periodic
potentials to simulate laser-solid interactions. We introduce a new perspective
in the coordinate space combined with the motion of the Bloch electron
wavepackets moving at group and phase velocities under the laser fields. This
model interprets the origins of the two contributions (intra- and interband
transitions) of the high-order harmonic generation (HHG) by investigating the
local and global behavior of the wavepackets. It also elucidates the underlying
physical picture of the HHG intensity enhancement by means of carrier-envelope
phase (CEP), chirp and inhomogeneous fields. It provides a deep insight into
the emission of high-order harmonics from solids. This model is instructive for
experimental measurements and provides a new avenue to distinguish mechanisms
of the HHG from solids in diffrent laser fields.