Reconstruction of Strong-Field-Driven Carrier Generation Dynamics from Injection Harmonics in Solid Dielectrics

Abstract

Non-perturbative low-order harmonics can be dominated by the nonlinearity of strong-field-ionization. We demonstrate the reconstruction of strong-field-driven carrier generation dynamics from ionization-related harmonics in fused silica using a phase-retrieval algorithm.

Linking High-Harmonic Generation and Strong-Field Ionization in Bulk Crystals

“…the transition from one atom to a neighbouring atom) is not included in the dipole momenta used in the SBE calculations the additionally emerging peaks leading to the eight-fold symmetry cannot be seen in the SBE results. Since the injection current is directly associated with interband excitations and thus contributes to P (ω) and since the recollision mechanism can be excluded due to the below-bandgap photon energy, we attributelike in our previous work [19,25] -the emission of H3 in the strong-field regime to the injection mechanism, the emission of harmonics due to the spatial displacement of electrons during the excitation process.…”

“…However, the strength of these velocity harmonics is expected to be insignificant under typical experimental conditions due to the modest photon energies that result in small excess velocities. Finally, the previously overlooked injection current, originating from the spatial displacement of an electron wavepacket during laser-driven tunneling ionization, was identified as the dominant source of low-order harmonic generation in fused silica [19,25]. The highly anisotropic angular dependence of the HHG process in crystalline solids has been correlated to the electronic band structure [13], petahertz photocurrents [26], real-space trajectories of electronic wavepackets [27] and van-Hove singularities [28,29].…”

“…Fourth, the nonlinearity that is inherent to the process of photoionization was proposed as a possible origin for harmonic generation [16,17]. Three possible ionization-related mechanisms have been * juergens@mbi-berlin.de discussed in the context of HHG [18,19]. Brunel harmonics, arising from the acceleration of quasi-free carriers excited by photoionization have been analyzed in gases, clusters, bulk solids and thin films [20][21][22][23][24].…”