Modeling Floating Potential Conductors Using Discontinuous Galerkin Method

Chen, Liang; Dong, Ming; Bağcı, Hakan

doi:10.1109/access.2020.2964385

Cited by 13 publications

(27 citation statements)

References 22 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…To compare the number of arithmetic operations required by the two implementations, one should first note that the curl operator C is the same in both formulations. Computation ofC requires those of the spatial derivatives and the numerical flux [34]- [36]. Here, the memory access time is much more significant than the time required to carry out these computations because data from neighboring elements, which are discontinuous in memory, is required.…”

Section: B Computational Complexitymentioning

confidence: 99%

A Memory-Efficient Implementation of Perfectly Matched Layer With Smoothly Varying Coefficients in Discontinuous Galerkin Time-Domain Method

Chen¹,

Ozakin²,

Ahmed³

et al. 2021

IEEE Trans. Antennas Propagat.

Self Cite

View full text Add to dashboard Cite

Wrapping a computation domain with a perfectly matched layer (PML) is one of the most effective methods of imitating/approximating the radiation boundary condition in Maxwell and wave equation solvers. Many PML implementations often use a smoothlyincreasing attenuation coefficient to increase the absorption for a given layer thickness, and, at the same time, to reduce the numerical reflection from the interface between the computation domain and the PML. In discontinuous Galerkin time-domain (DGTD) methods, using a PML coefficient that varies within a mesh element requires a different mass matrix to be stored for every element and therefore significantly increases the memory footprint. In this work, this bottleneck is addressed by applying a weight-adjusted approximation to these mass matrices. The resulting DGTD scheme has the same advantages as the scheme that stores individual mass matrices, namely higher accuracy (due to reduced numerical reflection) and increased meshing flexibility (since the PML does not have to be defined layer by layer) but it requires significantly less memory.

show abstract

Section: B Computational Complexitymentioning

confidence: 99%

A Memory-Efficient Implementation of Perfectly Matched Layer With Smoothly Varying Coefficients in Discontinuous Galerkin Time-Domain Method

Chen¹,

Ozakin²,

Ahmed³

et al. 2021

IEEE Trans. Antennas Propagat.

Self Cite

View full text Add to dashboard Cite

show abstract

“…For the Poisson equation, a potential-drop boundary condition is used along the x direction to mimic the bias voltage, periodic boundary conditions (PBCs) are used along the y direction, and a homogeneous Neumann boundary condition is used along the z direction. For the stationary DD equations, PBCs are used along x and y directions, and a homogeneous Robin boundary condition is used on the surfaces of the LT-GaAs layer (transverse to the z direction) [46], [47]. PBCs are used along the x and y directions for the timedependent Maxwell and DD equations.…”

Section: Mobilitymentioning

confidence: 99%

Analysis of Screening Effects on Terahertz Photoconductive Devices Using a Fully-Coupled Multiphysics Approach

Chen

Bağcı

2021

J. Lightwave Technol.

Self Cite

View full text Add to dashboard Cite

The terahertz current generated by a photoconductive device (PCD) saturates as the power of the input optical pump is increased. This behavior is induced by various screening effects that stem from the interactions between electromagnetic (EM) fields and semiconductor carriers. In this work, these screening effects are numerically analyzed for the first time using a fully-coupled multiphysics approach. Unlike the previously developed simulation frameworks, this approach rigorously models the nonlinear coupling between the EM fields and the carriers and therefore is capable of accounting for the screening effects. It is demonstrated that the results obtained using this multiphysics approach and actual experiments are in excellent agreement. The optical-and radiation-field screening effects are identified in the simulation results and the optical-field screening is found to play a more dominant role in the saturation of the PCD output under high optical pump power levels.

show abstract

“…The surfaces of the nanostructures are modeled as floating potential surfaces for the stationary state simulation (i.e., for solution of the Poisson equation) [22], [52]. Note that in the case of nanostructures being used as electrodes [53], one could use Dirichlet boundary condition with the bias voltage on the surface of the nanostructure.…”

Section: B Plasmonic Pcdmentioning

confidence: 99%

Multiphysics Simulation of Plasmonic Photoconductive Devices Using Discontinuous Galerkin Methods

Chen

Bağcı

2020

IEEE J. Multiscale Multiphys. Comput. Tech.

Self Cite

View full text Add to dashboard Cite

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 driftdiffusion (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.

show abstract

Modeling Floating Potential Conductors Using Discontinuous Galerkin Method

Cited by 13 publications

References 22 publications

A Memory-Efficient Implementation of Perfectly Matched Layer With Smoothly Varying Coefficients in Discontinuous Galerkin Time-Domain Method

A Memory-Efficient Implementation of Perfectly Matched Layer With Smoothly Varying Coefficients in Discontinuous Galerkin Time-Domain Method

Analysis of Screening Effects on Terahertz Photoconductive Devices Using a Fully-Coupled Multiphysics Approach

Multiphysics Simulation of Plasmonic Photoconductive Devices Using Discontinuous Galerkin Methods

Contact Info

Product

Resources

About