Abstract
Since the first demonstration of high-order harmonic generation (HHG) from solids in 2010 [1], there have been many works reported HHG from condensed matter and its spectroscopic applications. HHG has been shown first for a variety of materials, including semiconductors, insulators, epsilon-near-zero material, two-dimensional materials and recently topological surface states. In solids, HHG has been used as a probe of electronic properties, including the reconstruction of electronic bandstructure and Berry curvature. In addition, HHG from liquids has been demonstrated and it has a strong potential to probe electronic properties and dynamics of liquids using an all-optical approach. In this talk, we will discuss some emerging opportunities for scientific and industrial applications of high-order harmonic generation from condensed matter. In addition, we will discuss one example where high-harmonic spectroscopy can be used to probe lattice dynamics [2], obtaining both absolute electron-phonon coupling as well as anharmonic phonon-phonon coupling. Our technique is background-free and has extreme sensitivity directly in the energy domain. In combination with the optical deformation potential calculated from density functional perturbation theory and the absolute energy modulation depth, our measurement reveals the maximum displacement of neighboring oxygen atoms in α-quartz crystal to tens of picometres in real space. Our work opens a new realm for the accurate measurement of coherent phonons and their scattering dynamics, which allows for potential benchmarking ab initio calculations in solids.
References
- S. Ghimire et al., Nature Physics, 7, 138–141 (2011).
- J. Zhang et al., Nature Photonics, 18, 792-798 (2024).