Abstract: 

The interplay of intense ultrashort laser fields with bulk solids transcends the perturbative regime, giving rise to extreme nonlinear optics hallmarked by the emission of high-order harmonics. Since the pioneering demonstration of solid-state HHG in 2011, substantial strides have been made in unraveling the fundamental mechanisms underlying this phenomenon.

In this presentation, we delve into the relationship between laser-induced excitation and HHG in bulk solids. Through the utilization of a two-color wave-mixing experiment we gain insights into excitation-driven harmonic generation and strong-field-induced carrier dynamics on sub-cycle timescales. In further experiments we reveal intensified harmonic emission and enhanced excitation along specific lattice directions in crystalline targets and thereby identify a direct correlation betwen strong-field excitation and HHG.

Beyond these fundamental investigations a potential application of time-resolved high-harmonic spectroscopy for tracking ultrafast phase transitions in strongly correlated oxides will be showcased. The ability to resolve ultrafast dynamics in such materials holds promise for understanding electronic correlations and phase transitions on unprecedented timescales.