Abstract
High-order harmonics generation (HHG) has caused a wide interest because besides direct scientific studies, it is a powerful ultrashort coherent XUV and soft x-ray source, which has an excellent temporal and spatial resolution [1]. An important research direction of HHG is to obtain HHG with higher efficiency, including higher cutoff photon energy and higher conversion efficiency. A recent numerical model shows that the HHG from gases can be well modulated and controlled by pressure or gas density [2]. Stimulated by this idea, we propose a gas experiment working with a differentially pumped gas cell. We hope that this will provide the highest photon energy from gases. Another idea is to enhance the HHG by realizing quasi-phase-matching with periodic modulation. [3] To investigate this idea in solids, numerical simulations, such as the semiclassical Boltzmann equation and the semiconductor bloch equations and Maxwell equations, are employed. We are hopeful that this approach efficiently improve the HHG generation performance.
Reference :
[1] Winterfeldt, C., Spielmann, C., Gerber, G., 2008. Colloquium: Optimal control of high-harmonic generation. Reviews of Modern Physics 80, 117–140.. doi:10.1103/revmodphys.80.117
[2] Major, B., Varju, K., 2021. Extended model for optimizing high-order harmonic generation in absorbing gases. Journal of Physics B: Atomic, Molecular and Optical Physics.. doi:10.1088/1361-6455/ac3fbe
[3] Geissler, M., Tempea, G., Brabec, T., 2000. Phase-matched high-order harmonic generation in the nonadiabatic limit. Physical Review A 62.. doi:10.1103/physreva.62.033817
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