GPU-Accelerated Hybrid Discontinuous Galerkin Time Domain Algorithm With Universal Matrices and Local Time Stepping Method

Ban, Zhen Guo; Shi, Yan; Yang, Qi; Wang, Peng; Zhu, Shi Chen; Li, Long

doi:10.1109/tap.2020.2972404

Cited by 21 publications

(1 citation statement)

References 27 publications

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“…By applying the dispersive model into full-wave transient electromagnetic simulation algorithm, for instance discontinuous Galerkin time domain method [59,60], the macroscopic electromagnetic characteristics of the metamaterial modulators based on the photo-excited GaAs in THz regime can be solved, such as the near-field effect [1,61] and far-field response [48]. On the other hand, for the widely used 800 nm laser, the thickness of which the GaAs can be excited is about L = 1 µm [25,28].…”

Section: Numerical Examples and Discussionmentioning

confidence: 99%

A unified photo-excited GaAs model from ab initio simulation in terahertz regime

Huang,

Shi,

Meng

et al. 2024

J. Phys. D: Appl. Phys.

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In this paper, we present a uniﬁed model for gallium arsenide (GaAs) based on ab initio simulations which characterizes its terahertz (THz) properties when excited by optical pump. We use density functional perturbation theory (DFPT) to calculate the dielectric properties of GaAs, and investigate the relaxation time of photo-excited GaAs through electron-phonon interactions (EPIs). In light of the complexities arising from the mixed absorption mechanisms and the sensitivity of GaAs to laser parameters, we have developed a method that leverages time-dependent density functional theory (TDDFT) and Boltzmann transport theory. This approach enables us to establish an accurate relationship between the pump laser intensity and the carrier concentration by introducing the percentage of excited electrons, facilitating the quantitative characterization of GaAs’s response under different optical pump intensities. Using the microscopic material parameters solved by ﬁrst principles, we develop a uniﬁed Drude model to describe the macroscopic electromagnetic responses of photo-excited GaAs. We simulate several reported numerical examples of photo-excited GaAs, including a GaAs wafer and GaAs-based THz metamaterial modulators, to validate the proposed uniﬁed model as a reliable approach for predicting the THz properties of GaAs. The good agreement between the simulation and measurement results demonstrates that our model successfully captures the dynamic responses of photo-generated carriers and provides guidance for the design of optoelectronic devices based on GaAs. Furthermore, our modeling approach based on ab initio simulations is free from empirical parameters, providing a solid THz modeling method for other photo-excited semiconductor materials.

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Section: Numerical Examples and Discussionmentioning

confidence: 99%

A unified photo-excited GaAs model from ab initio simulation in terahertz regime

Huang,

Shi,

Meng

et al. 2024

J. Phys. D: Appl. Phys.

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Metal-like monoclinic phase and terahertz characteristics in ultrafast phase transition of photoexcited VO2

Guo Ban,

Shi,

Qian Huang

et al. 2024

Journal of Applied Physics

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Photoexcitation is a powerful way to induce phase transition of strongly correlated materials and dynamically control terahertz (THz) devices integrated with photoinduced phase transition (PIPT) materials. To clarify controversies over the physical mechanism between electronic insulator-metal transition (IMT) and structural phase transition (SPT) of photoexcited vanadium dioxide (VO2), the underlying atomic and electronic state changes during photoinduced monoclinic-to-rutile phase transition are illustrated, and the separation with different thresholds between the quasi-instantaneous IMT and the ultrafast SPT is discovered. Below the SPT threshold, there exist metastable states exhibiting the metal-like monoclinic phases, i.e., the strongest metallicity and weak monoclinic phases, when the bond lengths of the V–V pairs are closest. By analyzing the electronic transport properties of these metal-like monoclinic phases, the THz response of the whole phase transition process can be characterized for first time through the quantum-electromagnetic dispersion modeling method. The THz properties of the practical VO2 film are simulated and the great alignments between the measurements and the simulations verify the proposed analysis method, which provides a powerful exploration path and insights for the theoretical analysis and design verification of PIPT materials and their optoelectronic THz devices.

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Modeling Terahertz Properties of Vanadium Dioxide by Ab Initio Computational Scheme and its Experimental Verification

et al. 2022

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GPU-Accelerated Hybrid Discontinuous Galerkin Time Domain Algorithm With Universal Matrices and Local Time Stepping Method

Cited by 21 publications

References 27 publications

A unified photo-excited GaAs model from ab initio simulation in terahertz regime

A unified photo-excited GaAs model from ab initio simulation in terahertz regime

Metal-like monoclinic phase and terahertz characteristics in ultrafast phase transition of photoexcited VO2

Modeling Terahertz Properties of Vanadium Dioxide by Ab Initio Computational Scheme and its Experimental Verification

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