Effect of photoexcitation on high-harmonic generation in semiconductors

Solid-state high-harmonic generation is intrinsically sensitive to band structure, carrier population, and carrier scattering. As such, solid-state high-harmonic generation is increasingly used as a probe for femtosecond time-resolved pump-probe experiments. So far, most experimental pump-probe studies have reported photoexcitation-induced amplitude suppression of high-harmonic generation in solid-state media, yet the origins of this phenomenon remain elusive. Through simulations based on the semiconductor Bloch equations, we identify the dephasing of the coherent carrier population as the primary mechanism driving this suppression. Furthermore, we find band gap renormalization to be a source for phase shifts of high harmonics. We introduce an analytical model, based on a semi-classical action, that supports our numerical outcomes.