  Modulating electronic structure of two-dimensional (2D) materials represents
an exciting avenue for tailoring their optoelectronic properties. Here, we
identify a strain-induced, cooperative effect of intraband and interband
excitations contributing to high harmonic generation (HHG) in prototype
dichalcogenide MoS2 monolayer. We find that besides the dominant intraband
contributions, interband current is also indispensable in modulating HHG. The
HHG yields increase linearly with the compressive strain since flatter band
dispersion and Berry curvature enhance both interband and intraband dynamics.
Band structure can be retrieved with high reliability by monitoring the
strain-induced evolution of HHG spectra, suggesting that strain not only
provides an additional knob to control HHG in solids, but also marks a way
towards a complete understanding of underlying microscopic mechanisms.
