Cooper minimum of high-order harmonic spectra from an MgO crystal in an ultrashort laser pulse

Abstract

Cooper minimum structure of high-order harmonic spectra from atoms or molecules has been extensively studied. In this paper, we demonstrate that the crystal harmonic spectra from an ultrashort mid-infrared laser pulse also exhibit the Cooper minimum characteristic. Based on the accurate band dispersion and k-dependent transition dipole moment (TDM) from the first-principle calculations, it can be found that the harmonic spectra from MgO crystal along Γ-X direction present a dip structure in the plateau, which is originated from the valley of TDM by examining the distribution of the harmonic intensity at the k-space. The Cooper minimum feature in crystal HHG will pave a new way to retrieve the band information of solid materials by using HHG from the ultrashort mid-infrared laser pulse.PACS numbers:

Ab Initio Cluster Approach for High Harmonic Generation in Liquids

“…This should be investigated in future work. We emphasize that this is the first prediction of a structural minimum in the HHG spectra of a liquid system, which is equivalent to those seen in gases − and solids and which can potentially be used to probe correlations or other dynamical effects.…”

“…We have also shown that the HHG spectra from liquid methane exhibit some interesting characteristics that may be useful for ultrafast spectroscopy: (i) a local minimum in the perturbative harmonic region that might originate from shape resonances, which is enhanced in the liquid phase. (ii) An electronic-structure minimum that appears at 15–17 eV, which is the equivalent to those observed in gases − and solids . Both of these features could be utilized to study the various chemical and physical properties of liquids with ultrafast temporal resolution (e.g., dynamical correlations, dynamical polarizability, ion motion, etc.…”

“…(ii) An electronic-structure minimum that appears at 15–17 eV, which is the equivalent to those observed in gases 89 − 91 and solids. 92 Both of these features could be utilized to study the various chemical and physical properties of liquids with ultrafast temporal resolution (e.g., dynamical correlations, dynamical polarizability, ion motion, etc.).…”

“…(ii) An electronicstructure minimum that appears at 15−17 eV, which is the equivalent to those observed in gases 89−91 and solids. 92 Both of these features could be utilized to study the various chemical and physical properties of liquids with ultrafast temporal resolution (e.g., dynamical correlations, dynamical polarizability, ion motion, etc.). Apart from the specific predictions presented here, we believe that our approach might pave the way for feasible and accessible calculations of HHG in liquids, as well as other nonlinear processes including photoionization.…”

Laser ablation in air and its application in catalytic water splitting and Li-ion battery

“…Meanwhile, the development of energy materials is of equal importance, which helps the harvest, conversion, and storage of clean sources. Pulse laser has been widely used in time-resolved characterization methods, such as transient absorption or fluorescence spectrum, which facilitates greatly the development of fundamental science ( Tien et al., 1999 ; Zhao et al., 2019 , 2020 ). Meanwhile, in the field of nanomaterial fabrication, pulse laser has been also adopted broadly in a technology termed as laser ablation ( Zeng et al., 2012 ; Li et al., 2016 ).…”