This talk provides a brief overview of recent progress in understanding the fundamentals of solid-state HHG. It also includes details of an experiment, where a robust interferometric approach is employed to characterize high-harmonics from bulk crystals.
We switch the valley pseudospin in monolayer WSe2 and drive all-ballistic Dirac currents on a topological insulator on subcycle scales. A lightwave-driven scanning-tunneling microscope allows for the first-ever femtosecond single-molecule videography and reaction microscopy.
Extreme ultraviolet (EUV) pulses are produced through high-order harmonic generation in few micrometre thick liquid sheets operating in vacuum. The underlying mechanisms, including the extent of generation in liquid rather than surrounding gas, are characterized by scanning a number of laser and target parameters.
In centrosymmetric materials, even order harmonics that are normally forbidden can be produced in the presence of a symmetry-breaking electric field. This allows optical measurements of fields in semiconductors with high temporal and spatial resolution.
Recently, we have observed the generation of ionization harmonics by irradiating a fused silica sample with an intense (TW/cm$^2$ range) pump laser beam. We established that in our experiments, the conventional mechanism of Brunel-type emission only plays a marginal role in the production of ionization harmonics.
