Maxwell-Hydrodynamic Model for Simulating Nonlinear Terahertz Generation from Plasmonic Metasurfaces

TL;DR

This paper introduces a comprehensive time-domain hydrodynamic model coupled with Maxwell's equations to simulate both linear and nonlinear terahertz generation in plasmonic metasurfaces, enabling better design of THz emitters.

Contribution

It presents a novel coupled Maxwell-hydrodynamic simulation framework that captures full-wave physics and electron dynamics for nonlinear plasmonic nanostructures.

Findings

Accurately simulates linear plasmonic responses compared to Drude model.

Validates nonlinear terahertz emission via difference-frequency generation.

Provides a tool for designing broadband THz emitters.

Abstract

The interaction between the electromagnetic field and plasmonic nanostructures leads to both the strong linear response and inherent nonlinear behavior. In this paper, a time-domain hydrodynamic model for describing the motion of electrons in plasmonic nanostructures is presented, in which both surface and bulk contributions of nonlinearity are considered. A coupled Maxwell-hydrodynamic system capturing full-wave physics and free electron dynamics is numerically solved with the parallel finite-difference time-domain (FDTD) method. The validation of the proposed method is presented to simulate linear and nonlinear responses from a plasmonic metasurface. The linear response is compared with the Drude dispersion model and the nonlinear terahertz emission from a difference-frequency generation process is validated with theoretical analyses. The proposed scheme is fundamentally important to design nonlinear plasmonic nanodevices, especially for efficient and broadband THz emitters.