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Subcycle interference in high-order harmonic generation from solids
摘要： Different from the high-order harmonic generation (HHG) from gases, we ?nd that the yield of HHG from solids exhibits unexpected modulations as a function of the driving laser intensity and wavelength. Its mechanism can be unraveled by the interference between currents inside the solids induced by two adjacent Zener tunneling events. Our simulations agree well with the experimental measurements of HHG from ZnSe and solid Ar. We also ?nd that the dephasing time plays a key role in this subcycle interference and can turn it on or off by controlling the overlap between the channels. It provides an avenue to optimize the ultrafast electron dynamics and HHG emission processes in solids, which will be useful for the compact ultrafast EUV light sources. We also propose an experimental scheme by using ultrashort lasers to explore this interference in other solid materials.
关键词： high-order harmonic generation,solids,ultrafast electron dynamics,Zener tunneling,dephasing time
更新于2025-09-04 15:30:14
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Wavelength dependence of high-order harmonic yields in solids
摘要： We theoretically investigate the wavelength dependence of high-order harmonic yields in solids driven by a mid-infrared laser field. By solving the three-dimensional two-band density matrix equations in the wavelength range of 2.0–7.5 μm, it is shown that, in the limit of slow dephasing (dephasing time T2 → ∞), the high-order harmonic yield from a crystal follows a scaling of λ?4 for a fixed energy interval. The λ?4 scaling is attributed to the wave-packet spreading (λ?3) for the overall yield and the energy distribution effect (λ?1) due to the increase of the cutoff. For the crystal with a finite dephasing time T2, we find that the exponential factor x of λ?x increases with a decay of T2. An apparent and rapid fluctuation on a fine wavelength mesh is also observed in the harmonic yields. The fine-scale oscillation originates from the quantum interference effect, and the corresponding modulation period δλ scales as λ?1.
关键词： high-order harmonic generation,solids,wavelength dependence,mid-infrared laser field,quantum interference
更新于2025-09-04 15:30:14