Extracting electron dynamics in solids via observation of low-order harmonics of tailored strong fields.

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Recent advances in attosecond science herald a paradigm change in solid-state physics. The old framework, based on long pulses and a frequency domain analysis is being currently replaced by the new one, relying on a time-based picture and strong ultrashort pulses. In this project we aim to look inside the optical cycle to reconstruct the attosecond inter- and intraband dynamics in solids using temporally and polarizationally tailored two-color fields as well as tailored sample geometries based on photonic crystals and nanostructures to facilitate phase-matching and symmetry breaking. We use the intracavity enhanced near-infrared driving fields available from the first QUTIF period. In these tailored fields, lowest radiation harmonics are efficiently generated. The harmonics are carefully analyzed with a scheme developed in the previous QUTIF period as well, the so-called all-optical attoclock, allowing to reconstruct the details of electron dynamics such as ionization delay on attosecond time scales. Theory predicts that the all-optical attoclock is capable of disentangling the different mechanisms behind the generation of low-order harmonics, namely the susceptibility contribution (bound-bound), the Brunel radiation (bound-free), and finally the re-collision harmonics (bound-free-bound). Aim of this project is the first experimental demonstration of the all-optical attoclock and the investigation of the nonlinear electron dynamics in semiconductors and dielectrics on the sub-cycle scale in close interplay between experiment and theory. This leads not only to a better understanding of the nonlinear optical properties of solids, but also to efficient harmonic sources e.g. in the THz spectral range.