3D FDTD Algorithm Research Articles

Optimization of gold square-shaped nanopillars arrays for high-efficiency optronics

Parametric optimization of gold (Au) square-shaped nanopillars (AuNPLs) arrays deposited on glass substrate (AuNPLs/glass) was performed through optical characteristics for high-performance optical detection and biosensing purpose from visible to very near-infrared spectral (0.5 ≤λ≤0.8μm). This is aimed at predicting optimum parameters which result in strong enhancement for next-generation optronic devices. The optimization parameters were limited to the AuNPLs height (H), the interslit distance (W1), and the slit width (W2) in investigating the optical characteristics of reflectance, transmittance, and absorption. In achieving this, the extraordinary surface plasmon resonance (SPR) mechanism was explored using 3D finite-differential time-domain (3D-FDTD) algorithm. Based on the periodical nature of the AuNPLs array, periodic boundary conditions (PBCs) and stretched coordinate perfectly matched layers (SCPML) boundaries were employed for the computation region with a plane wave source injection at normal incidence (θ=0°). The results revealed new insights on the AuNPLs/glass structure and might inspire potential applications such as photodetectors and biosensors with optimum device achieved by controlling H from 0.1 to 1.0μm while W1=0.25μm and W2=0.1μm are kept constants and spectroscopy with optimum device by controlling W1 from 0.1 to 1.0μm while H=0.4μm and W2=0.1μm are maintained constants. Besides, application of biosensor performs sensitivity (S) of 380.14 nm/RIU (nanometer/refractive index unit) and 377.32 nm/RIU with corresponding highest figure of merit (FOM) of 8.02 RIU−1 and 11.11 RIU−1 for H=400 nm and H=600 nm, respectively.

The Three Dimension First-Order Symplectic Partitioned Runge-Kutta Scheme Simulation for GPR Wave Propagation in Pavement Structure

Numerical simulation of three-layer layered electromagnetic waves is key problem for nondestructive testing of ground penetrating radar (GPR) pavement. In this paper, the difference iterative scheme of three-dimensional first-order symplectic partitioned Rung-Kutta is derived, which is applied to pavement detection of ground penetrating radar by using Higdon ABC boundary condition. Incident waves are considered as line sources. The accuracy and efficiency of the proposed algorithm are verified by the traditional 3D-FDTD algorithm. The results indicate that the accuracy and efficiency between the two methods are consistent. Unlike the traditional 3D-FDTD algorithm, the CPU time of the proposed method is reduced by 30%. The diseases location of the pavement structure is directly reflected by the numerical simulation result of the proposed method. This provides a three-dimensional symplectic partitioned Rung-Kutta algorithm, which can be applied to the forward simulation of GPR. It provides a three-dimensional symplectic partitioned Rung-Kutta algorithm, which can be applied to the forward simulation of GPR. The accurate electromagnetic response information of the target can be obtained by the proposed method.

Accurate development of the UPML absorbing boundary conditions in a 3D-FDTD algorithm for CPW and microstrip line on silicon substrate

We present a theoretical investigation and application of an unsplit formulation of the perfectly matched layer absorbing boundary conditions (PML ABC), developed here especially for lossy-media FDTD simulations. From the uniaxial PML (UPML) theory, and unlike Berenger's technique, in this paper the anisotropic absorbing medium is based on a Maxwellian formulation. In order to validate the theoretical findings, we have investigated a coplanar waveguide (CPW) on low-cost and low-resistivity silicon substrate. Moreover, we compare our results with other published works. © 2005 Wiley Periodicals, Inc. Microwave Opt Technol Lett 44: 334–338, 2005; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20627

A 3D multimodal FDTD algorithm for electromagnetic and acoustic propagation in curved waveguides and bent ducts of varying cross‐section

This paper presents a curvilinearly‐established finite‐difference time‐domain methodology for the enhanced 3D analysis of electromagnetic and acoustic propagation in generalised electromagnetic compatibility devices, junctions or bent ducts. Based on an exact multimodal decomposition and a higher‐order differencing topology, the new technique successfully treats complex systems of varying cross‐section and guarantees the consistent evaluation of their scattering parameters or resonance frequencies. To subdue the non‐separable modes at the structures' interfaces, a convergent grid approach is developed, while the tough case of abrupt excitations is also studied. Thus, the proposed algorithm attains significant accuracy and savings, as numerically verified by various practical problems.

Light transmission by subwavelength annular aperture arrays in metallic films

We study the spectral response of a metallic film with an engraved 2D periodic structure of annular apertures. We show that an enhanced transmission can be obtained and can reach 90%. The variation of the spectral response as a function of the film thickness from 150 nm to a value of 1.8 μm is also studied. We show that a guided mode in the subwavelength coaxial structure is responsible for this large transmission. A wavelength cut-off exists. We study the transmission characteristics on the optical and geometrical parameters of the array (period, coaxial radii, incident polarization and dielectric constants) using a 3D-FDTD algorithm.

Simulation of cellular phone antennas by using inductive lumped elements in the 3D-FDTD algorithm

Simulation of cellular phone antennas by using inductive lumped elements in the 3D-FDTD algorithm

A Fast FDTD Analysis of Guided Wave Structures Using a Continuously Variable Mesh with Second Order Accuracy

This paper describes some important improvements to the FDTD method. First, a two-dimensional FDTD algorithm for hybrid mode analysis is described. By using a phase shift of β.Δz along the z-direction for the limiting case of Δz → 0, the propagation constant of hybrid modes can be calculated with only a two-dimensional mesh and a truly two-dimensional grid size. Second, a continuously variable grading scheme is introduced in which the first order error term is eliminated and a second order accuracy is achieved without using additional wave equations at the boundary of neighbouring lattices. This grading scheme can be applied to the 2D as well as to the 3D FDTD algorithm. Both developments represent important improvements in terms of computational efficiency of the FDTD method.