Plasmonic nanostructures significantly improve the performance of photoconductive devices (PCDs) in generating terahertz radiation. However, they are geometrically intricate and result in complicated electromagnetic (EM) field and carrier interactions under a bias voltage and upon excitation by an optical EM wave. These lead to new challenges in simulations of plasmonic PCDs, which cannot be addressed by existing numerical frameworks. In this work, a multiphysics framework making use of discontinuous Galerkin (DG) methods is developed to address these challenges. The operation of the PCD is analyzed in stationary and transient states, which are described by coupled systems of the Poisson and stationary drift-diffusion (DD) equations and the time-dependent Maxwell and DD equations, respectively. Both systems are discretized using DG schemes. The nonlinearity of the stationary system is accounted for using the Gummel iterative method while the nonlinear coupling between the time-dependent Maxwell and DD equations is tackled during time integration. The DG-based discretization and the explicit time marching help in handling space and time characteristic scales that are associated with different physical processes and differ by several orders of magnitude. The accuracy and applicability of the resulting multiphysics framework are demonstrated via simulations of conventional and plasmonic PCDs.

中文翻译：

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使用不连续伽辽金方法对等离子体光电导器件进行多物理场仿真

等离子体纳米结构显着提高了光电导器件 (PCD) 在产生太赫兹辐射方面的性能。然而，它们在几何上是复杂的，并且在偏置电压和光学 EM 波的激发下导致复杂的电磁 (EM) 场和载流子相互作用。这些给等离子体 PCD 的模拟带来了新的挑战，这是现有数值框架无法解决的。在这项工作中，开发了一个利用不连续伽辽金 (DG) 方法的多物理场框架来解决这些挑战。PCD 的运行在稳态和瞬态下进行分析，这分别由泊松和稳态漂移扩散 (DD) 方程以及瞬态麦克斯韦方程和 DD 方程的耦合系统描述。两个系统都使用 DG 方案进行离散化。固定系统的非线性使用 Gummel 迭代方法来考虑，而时间相关的麦克斯韦方程和 DD 方程之间的非线性耦合在时间积分过程中得到解决。基于 DG 的离散化和显式时间推进有助于处理与不同物理过程相关且相差几个数量级的空间和时间特征尺度。通过对传统和等离子体 PCD 的模拟，证明了所得多物理场框架的准确性和适用性。基于 DG 的离散化和显式时间推进有助于处理与不同物理过程相关且相差几个数量级的空间和时间特征尺度。通过对传统和等离子体 PCD 的模拟，证明了所得多物理场框架的准确性和适用性。基于 DG 的离散化和显式时间推进有助于处理与不同物理过程相关且相差几个数量级的空间和时间特征尺度。通过对传统和等离子体 PCD 的模拟，证明了所得多物理场框架的准确性和适用性。