New Routes for Label-Free Super-Resolution Microscopy and Attosecond Science via Transient High-Harmonic Generation

While the upconversion of infrared driving lasers into soft-X-ray pulses by high-harmonic generation (HHG) in gases has become an established technique for attosecond science and nanoscale imaging [1-3], HHG in solids is less explored. Gas-phase HHG is highly sensitive and thus controllable with regards to the microscopic generation mechanism, and the macroscopic buildup of emission via phase matching [4,5]. Parallels between solid and gas-phase HHG suggest that solid-state HHG may be controlled in similar manners, which would enable a generally applicable all-optical light switch with wide application potential.

In this talk I will introduce femtosecond resolved solid-state HHG and highlight the applications of solid-state HHG for metrology, spectroscopy and imaging with recent examples from our group.
On the nanoscale, we controlled HHG via engineering the surface topography of solids, which in turn demonstrates how solid HHG can be used for metrology on surfaces and tailored as a light source [6].
On the femtosecond time scale, we used the sensitivity of HHG to electronic band structure to follow ultrafast phase transitions in strongly correlated materials [7], and photocarrier dynamics in perovskites [8].
While the first set of measurements mentioned above showed nanoscale sensitivity, the second set of experiments demonstrated that photoexcitation can be used to control light emission via solid-state HHG.
Combining both efforts, I will outline and show first results how ultrafast control of solid HHG enables harmonic deactivation microscopy (HADES) - a label-free super-resolution microscopy below the diffraction limit of light [9].

Thinking ahead, the development of these techniques may enable resolution on the nanometer and femto- to attosecond scale fitted into a regular microscopy setting, with application potential ranging from strongly correlated materials to semiconductor metrology, photosynthetic processes, and medical imaging.

References:
[1] P.M. Kraus, H.J. Wörner, Angewandte Chemie International Edition 57, 5228 (2018).
[2] P.M. Kraus, M. Zurch, S.K. Cushing, D.M. Neumark, S.R. Leone, Nature Reviews Chemistry 2, 144 (2018).
[3] P.M. Kraus et al., Science 350, 790 (2015).
[4] S. Roscam Abbing, F. Campi, F.S. Sajjadian, N. Lin, P. Smorenburg, P.M. Kraus, Physical Review Applied 13, 054029 (2020).
[5] S. Roscam Abbing, F. Campi, A. Zeltsi, P. Smorenburg, P.M. Kraus, Scientific Reports 11, 24253 (2021).
[6] S.D.C. Roscam Abbing, et. al., P.M. Kraus; Physical Review Letters 128, 223902 (2022).
[7] Z. Nie et al., Peter M. Kraus, Physical Review Letters, in review (2023).
[8] M. v.d. Geest, J.J. de Boer, K. Murzyn, P. Juergens, B. Ehrler, P.M. Kraus, Journal of Phys. Chem. Lett., in review (2023).
[9] K. Murzyn et al., P.M. Kraus, in preparation.