Enhanced high-harmonic generation (HHG) from Cr-doped MgO crystals *

HHG from crystals is a new source of coherent extreme ultraviolet (XUV) attosecond radiation [1], which also allows the retrieval of band structure information [2]. Increasing the HHG yield and cutoff are fundamental to developing efficient XUV sources. We investigate an alternative way of boosting the HHG yield based on doping. The presence of dopants results in new electronic states in the band gap, as well as lattice defects, which modify the minimum band gap. Since the interband HHG yield depends exponentially on the minimum band-gap energy EG of the solid [3], one can expect a substantial change of the HHG yield by reducing EG [4]. We show the first experimental observation of impurity-enhanced HHG yields that is supported by our numerical solutions of the Semiconductor Bloch Equations [5].

 

[1] G. Vampa, et al., IEEE J. Sel. Top. Quantum Electron. 21, 8700110 (2015).

[2] N. Tancogne-Dejean, et al., Phys. Rev. Lett. 118, 087403 (2017).

[3]  Navarrete, et al., Phys. Rev. A 100, 033405 (2019).

[4] T. Huang, et al., Phys.Rev. A 96, 043425 (2017).

[5] Nefedova, et al., arXiv:2001.00839 (2020).