Extreme nonlinear optics in solids: Linking High Harmonics from gases and solids


Extreme Nonlinear Optics in Solids

When intense light interacts with an atomic gas, recollision between an ionizing electron and its parent ion creates high-order harmonics of the fundamental laser frequency. This sub-cycle effect generates coherent soft X-rays and attosecond pulses and provides a means to image molecular orbitals. We generate high harmonics from bulk ZnO (a direct band gap semiconductor) and Si (an indirect band gap semiconductor) crystals and demonstrate their origin in a generalized recollision between electrons and their associated holes [1-3]. In addition, we find that solid state high harmonics are perturbed by fields so weak that they are present in conventional electronic circuits, thus opening a route to integrate electronics with attosecond and high-harmonic technology [4]. Finally, we devise a technique that extracts the solid’s band structure from the high harmonic signal [5]. This all-optical technique will be applicable to study matter under extreme conditions, surface reactions at ambient pressures and ultrafast modifications to band structures.

[1] Vampa, G., et al. Nature 522.7557 (2015): 462-464.
[2] Vampa, G., et al. PRL 113.7 (2014): 073901.
[3] Vampa, G., et al. PRB 91.6 (2015): 064302.
[4] Vampa, G., et al. Nature Photonics 12.8 (2018): 465-468.
[5] Vampa, G., et al. PRL 115.19 (2015): 193603.

Attosecond Science at uOttawa and NRC