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MON: Monday Contributed Sessions

MON 23: Poster Session: Fundamental Aspects and Model Systems

MON 23.28: Poster

Monday, September 8, 2025, 18:30–20:30, ZHG Foyer 1. OG

Probing High-Order Susceptibilities of monolayer MoS₂ via High Harmonic Generation: TDDFT approach — Yeganeh Alvankar^1,2, •Elnaz Irani², Hamid Talkhabi², and Mohammad Monfared³ — ¹3ICMM, Centro Superior de Investigaciones Cientficas, Sor Juana Ines de la Cruz, 3 Cantoblanco, 28049 Madrid, Spain — ²Department of Physics, Faculty of Basic Sciences, Tarbiat Modares University, P.O. Box 14115-175, Tehran, Iran — ³Institute of Theoretical Physics, Leibniz University Hannover, Appelstraße 2, 30167 Hannover, Germany

High-harmonic generation (HHG) is a powerful method for probing high-order nonlinear optical responses in solids, across both perturbative and non-perturbative regimes.

Here, we use time-dependent density functional theory (TDDFT) to calculate the nonlinear susceptibilities (χ⁽⁵⁾, χ⁽⁷⁾, χ⁽⁹⁾) of monolayer MoS₂ via HHG. Simulations employ intense ultrafast laser pulses (λ₀ = 600,nm) with peak intensities from 0.2-1.2 TW/cm².

Our results exhibit power-law scaling Yield_N = A_N I^N and interband polarization, enabling direct extraction of higher-order susceptibilities. We also observe strong crystal orientation dependence, with anisotropic behavior across harmonic orders, emphasizing the role of polarization control in 2D material characterization.

Unlike previous methods (e.g., attosecond streaking) that inferred lower-order susceptibilities indirectly, HHG directly reveals higher-order responses without broad spectra or indirect analysis. Quantifying such nonlinearities is key to advancing ultrafast photonics.

Keywords: High Harmonic Generation; Nonlinear Optics; 2D materials; High-Order Susceptibilities