Multiresolution Time-domain Research Articles

Composite scattering characteristics analysis of micro-ellipsoidal periodic structure optical surface and microdefects

In order to adjust and detect micro-nano periodic structure optical surface accurately and efficiently, the problem of composite scattering between micro-ellipsoidal periodic structure optical surface and pore defects is studied use the multi-resolution time domain (MRTD) approach. A calculation model is established for the intensity distribution of composite scattering, which is modulated by the micro-ellipsoidal periodic structure optical surface and microdefects. Results are in good agreement with those obtained using CST Microwave Studio software and the finite-different time-domain (FDTD) approach, which demonstrates the effectiveness of the calculation model and method. By combining the field distribution of the micro-ellipsoidal periodic structure optical surface containing microdefects with the optical response at different wavelengths, it is necessary to study the influence of various parameters of the micro-ellipsoidal structure and microdefects on the optical system of metamaterials. The effects of the parameters such as roughness, structure of micro-ellipsoidal unit, defect sizes and buried depths on the composite scattering characteristics are analyzed numerically. The results provide technical support for the fields of functional surface design, ultrasensitive detection, scattering peak orientation and frequency selection.

Proposal and Analysis of Coaxial-Through-Glass Vias in 3-D Integration Using Multiresolution Time-Domain (MRTD) Technique

Proposal and Analysis of Coaxial-Through-Glass Vias in 3-D Integration Using Multiresolution Time-Domain (MRTD) Technique

Crosstalk noise analysis of coupled on-chip interconnects using a multiresolution time domain (MRTD) technique

Crosstalk noise analysis of coupled on-chip interconnects using a multiresolution time domain (MRTD) technique

Transient Analysis of Crosstalk Noise Effects in SWCNT Bundle On-Chip Interconnects Using MRTD Technique

Carbon nanotube bundles are being considered as a potential on-chip interconnect replacement for conventional copper on-chip interconnects in the nanoscale regime of recent IC technology. This paper analyzes the signal integrity analysis of CMOS gate-driven single-walled carbon nanotubes (SWCNTs) bundle on-chip interconnects. The wavelet-based numerical model Multiresolution Time Domain (MRTD) method is used for the transient analysis of SWCNTs bundles on-chip interconnects. The proposed MRTD model is used to perform transient analysis for parameters of signal integrity, peak crosstalk, and propagation delay estimations. The obtained results of the proposed MRTD model are compared with those of the conventional Finite Difference Time Domains (FDTD) model and it is validated with SPICE simulator at 32 nm technology node and also compared with multiwalled CNT (MWCNT) interconnects at 22 nm. The MRTD model results show excellent agreements to SPICE with less than 0.41% error. The elapsed CPU runtimes for the MRTD model are significantly less compared to SPICE. The MRTD model is used to interconnects the model with two and three lines and can be extended to an M-coupled line. The results of the proposed model are closely matched to those of SPICE simulations.

A study on reflection and transmission characteristics of magnetized plasma based on S-MRTD scheme

Employing symplectic algorithm in electromagnetic simulation enables the advantages of energy conservation, high stability, low dispersion and high accuracy to be maintained. A new numerical scheme for simulating magnetized plasma, which is symplectic multi-resolution time-domain (S-MRTD) scheme is presented. First, the discrete iterative process of S-MRTD scheme for magnetized plasma is constructed based on the symplectic operator technique. Then, the correctness and effectiveness of the S-MRTD scheme framework are verified by the numerical simulation of left-handed circular polarized wave (LCP) and right-handed circular polarized wave (RCP). Finally, the influence of electron cyclotron frequency(wb) on reflection and transmission coefficients is analyzed based on S-MRTD scheme.

Studies on photonic bandgap and its defect mode characteristics of plasma photonic crystals based on S-MRTD scheme

Photonic bandgap (PBG) and its defect mode are two representative characteristics of plasma photonic crystals (PPC), which make them have important industrial applications in photonic crystal waveguides, filters, antennas, and other devices. In this paper, we apply the symplectic multi-resolution time-domain (S-MRTD) scheme to analyze these two properties. Firstly, the characteristics of PBG are analyzed. Secondly, the characteristics of defect mode in the case of a single defect layer and multi-defect layers are adequately studied. Finally, two types of ternary PPC are further simulated. Numerical simulations demonstrate the feasibility and effectiveness of the proposed scheme, a desirable PBG and its defect mode can be obtained by altering the corresponding plasma parameters and dielectric parameters.

A conformal symplectic multi-resolution time-domain method with ADE-PML

In this paper, the conformal finite-difference time-domain (CFDTD) technique and the concept of effective dielectric constant are applied to symplectic multi-resolution time-domain (SMRTD) algorithm based on Daubechies scaling functions, resulting in a conformal SMRTD (C-SMRTD) method. Moreover, a novel implementation of perfect matched layer with auxiliary differential equation (ADE-PML) is presented for the SMRTD method. Numerical results of the radar cross section (RCS) of a dielectric sphere verify the effectiveness of the C-SMRTD method, which shows good agreement with the results derived by analytical methods. It is also shown that the accuracy of the C-SMRTD method has been significantly improved compared with the MRTD method with step approximation, and the proposed method has an advantage over CFDTD at saving the CPU time and memory. Furthermore, a vault-top tunnel model is established with the proposed method, and the characteristic of the field cross-section distribution of the electromagnetic pulse (EMP) propagation in the tunnel model is also presented and discussed.

Study on electromagnetic characteristics of plasma model-based on the symplectic multiresolution time-domain scheme

A novel numerical computation scheme, which is symplectic multiresolution time-domain (S-MRTD) scheme, for modeling plasma model is proposed. The loss plasma dispersive model is taken into account in S-MRTD scheme, and the detailed formulations of the proposed S-MRTD scheme are also provided. A one-dimensional perfectly matched layers (PML) are used to terminate the computational domain. The analyses of stability and numerical dispersion demonstrate that S-MRTD scheme is more efficient than traditional finite-different time-domain (FDTD) and MRTD methods. The energy conservation characteristics of S-MRTD scheme in electromagnetic simulation are proved by the propagation of pulse in free space for long-term simulation. In the end, the S-MRTD formulations are confirmed by computing the electric field intensity, reflection and the transmission coefficients for the pulse wave through an unmagnetized plasma slab. A favorable agreement between the numerical solutions is demonstrated, and the efficiency of the proposed scheme is verified. Meanwhile, numerical results show that plasma frequency, collision frequency and thickness are important factors affecting reflection and transmission coefficients.

基于优化辛时域多分辨率算法的光子晶体传输特性分析

基于优化辛时域多分辨率算法的光子晶体传输特性分析

An efficient one-dimensional time-domain algorithm for obliquely incident plane wave in BOR-SMRTD

In this paper, the concept of body of revolution (BOR) finite-difference time-domain method time-domain (BOR-FDTD) method is applied to symplectic multi-resolution time-domain (SMRTD) algorithm to propose a BOR-SMRTD method. In order to solve the problem that the obliquely incident pulse wave cannot be directly introduced into BOR-SMRTD method, an efficient one-dimensional time-domain algorithm for propagating obliquely incident pulse plane wave in BOR-SMRTD method is also proposed. The numerical results show that the proposed algorithm runs 51 times faster than the algorithm based on fast Fourier transform (FFT) completely. Moreover, the scattering problem of a perfect electric conductor (PEC) cylinder with finite length is calculated to verify the effectiveness of the algorithm. The surface current density distribution along a generatrix of the cylinder at a giving frequency was extracted, and the results are in good agreement with that obtained with the methods of moment (MoM) and BOR-FDTD. Finally, the radar cross section (RCS) of a PEC sphere was calculated, and the results agree well with the theoretical values.

Symplectic MRTD for solving three‐dimensional Maxwell equations based on optimised operators

A new set of symplectic operators for the symplectic multi-resolution time-domain (S-MRTD) method is obtained by using the time reversible constraint and the growth factor. Then, the perfectly matched layer absorbing boundary condition based on splitting field technique is introduced into the S-MRTD method and its iterative formula is derived. The stability and numerical dispersion of S-MRTD method with optimised symplectic operators are discussed in detail. Finally, the optimal S-MRTD method is applied to the calculation of electromagnetic radiation and scattering. Numerical calculation and simulation results show that the S-MRTD is more accurate and efficient than the traditional FDTD method.

A novel symplectic MRTD scheme studies on numerical characteristics of plasma photonic crystals

A novel symplectic multi-resolution time-domain (S-MRTD) scheme is put forward for simulating the one-dimensional unmagnetized plasma photonic crystals (PPCs). The lossless plasma model is taken into account in S-MRTD scheme, and the detailed calculation formulas of the proposed scheme are provided. An one-dimensional perfectly matched layers (PML) technique is used to truncate the computational domain, and the corresponding formulas are also derived. From the perspective of numerical stability and dispersion characteristics, it is shown that the S-MRTD scheme is more effective than the traditional time-domain methods. The propagation process of electromagnetic (EM) waves in one-dimensional PPCs structure are simulated by S-MRTD scheme, and from the perspective of frequency domain, the reflection and transmission cofficients of EM pulse waves through the PPCs are analyzed. Meanwhile, The characteristics of photonic band gaps (PBGs) are studied based on different parameters. Numerical simulations show that plasma frequency, dielectric constant, periodic thickness, number of periods, the thickness ratio of plasma and medium are important factors affecting the characteristics of PBGs.

Design and Validation of the Invariant Imbedded T-Matrix Scattering Model for Atmospheric Particles with Arbitrary Shapes

Light scattering by non-spherical particles is an important factor influencing atmospheric radiative transfer. To accurately simulate the scattering properties of non-spherical particles, the Invariant Imbedded T-matrix method (IIM T-Matrix) is developed by combining the Lorenz–Mie theory and invariant imbedding technique. In this model, the non-spherical particle is regarded as an inhomogeneous sphere and discretized into multiple spherical layers in the spherical coordinate system. The T-matrix of the inscribed sphere is firstly calculated by the Lorenz–Mie theory, and then taking it as the initial value, the T-matrix is updated layer by layer by using the invariant imbedding technique. To improve the computational efficiency, the model is further parallelized by the OpenMP technique. To verify the simulation accuracy of the IIM T-Matrix method, the results of the model are compared with those of the EBCM (Extended Boundary Condition Method) T-Matrix method, DDA (Discrete Dipole Approximation) and MRTD (Multi-Resolution Time Domain). The results show that the scattering phase matrix simulated by the IIM T-Matrix method closely agrees with that of the well-tested models, indicating that the IIM T-Matrix method is a powerful tool for the light scattering simulation of non-spherical particles. Since the IIM T-Matrix method is derived from the volume integral equation, compared to the T-Matrix method which is based on surface integral principles (i.e., “EBCM” or the “null field method”), it can be applied to the scattering calculations of particle with arbitrary shapes and inhomogeneous compositions, which can greatly expand the application scope of the T-Matrix method.

A Multiresolution Time Domain (MRTD) Method for Crosstalk Noise Modeling of CMOS-Gate-Driven Coupled MWCNT Interconnects

In this paper, the multiresolution time domain (MRTD) method with its unique features is tailored for modeling interconnects. To build further credence to this and its profound existence in the recent state-of-the-art, simulations for inclusive crosstalk noise, on complementary metal-oxide semiconductor gate-driven mutually coupled multi-walled carbon nanotube interconnect lines, using MRTD method and conventional finite-difference time-domain (FDTD) model for 32-nm technology are executed. The results demonstrate the dominance of MRTD model over conventional FDTD in terms of accuracy with respect to recursive simulations of Synopsys HSPICE tool. An average error of less than 0.2% is observed in the estimation of dynamic crosstalk noise analysis. The proposed method is used to model interconnects with two and three mutually coupled lines and can be extended for N-coupled lines. The results of the transient analysis prove the efficiency of MRTD method over HSPICE with respect to computational time. The proposed method can also be used to address the issues of electromagnetic compatibility and electromagnetic interference of on-chip interconnects.

Stability and numerical dispersion analysis of symplectic multi-resolution time-domain method

In this paper, first, the theoretical framework of symplectic multi-resolution time-domain (S-MRTD) method is mentioned, and the order condition of pth-order symplectic integrator is given. Then, the stability and dispersion analysis for symplectic multi-resolution time-domain (S-MRTD) methods are presented. To the best of our knowledge, there is a comperhensive study on the dispersion characteristics for pth-order S-MRTD scheme in the temporal direction, and this study will be useful for the selection and evaluation of various order symplectic integrator propagators. In addition, it is compared with the alternating direction implicit multi-resolution time-domain (ADI-MRTD) and runge-kutta multi-resolution time-domain (RK-MRTD) based on the Daubechies scale functions. Numerical results show high efficiency and accuracy of the S-MRTD method.

Research on resolution test system of LLL and infrared fusion equipment

Based on the analysis of the resolution test system for low-light level(LLL) vision equipment and the multi-resolution time domain (MRTD) test system for infrared equipment, the conception of resolution test scheme for LLL and infrared image fusion equipment was proposed. The exiting equipment of infrared MRTD test system was utilized, the resolution test system of the LLL and infrared fusion image was established by modifying light source, incident light path and target plate, and the analysis on the scheme was conducted.Results indicate that the modified test system can both realize infrared reflection and low-light projection. The measurement accuracy of infrared temperature difference is close to 0.01 K, and the measurement accuracy of low-light illumination can reach 1 lx. The test of fusion image resolution meets the requirement of multiple decrement(1/62≈0.891).

ADI-MRTD Algorithm for Periodic Structures Analysis

In this paper, a novel algorithm based on the alternating direction implicit (ADI) multiresolution time-domain (MRTD) method for periodic structure simulation is proposed. By applying the multiresolution analysis in accordance with wavelet theory, the spatial sampling rate of the conventional finite-difference time-domain (FDTD) is significantly reduced by the MRTD method. The ADI method is then used to remove the Courant-Friedrich-Levy (CFL) limit that the MRTD method experiences. The periodic boundary condition (PBC) is directly implemented in the time domain using a constant transverse wave-number (CTW) wave. Numerical results are presented to confirm the efficiency and accuracy of the proposed method.

A novel MRTD model for signal integrity analysis of resistive driven coupled copper interconnects

PurposeThis paper aims to model the coupled on-chip Copper (Cu) interconnects by using the multiresolution time-domain (MRTD) method.Design/methodology/approachThe proposed model is a wavelet-based numerical method for analyzing signal integrity and propagation delay of coupled on-chip interconnects. Moreover, the dependency of crosstalk noise and delay on coupling parasitics (L12, C12) are analyzed.FindingsThe proposed MRTD method captures the behaviour of propagation delay and peak crosstalk noise on victim line against coupling parasitics, which is in close agreement with that of H simulation program with integrated circuit emphasis (HSPICE). The average error for the proposed model is less than 1 per cent with respect to HSPICE for the estimation of peak crosstalk noise voltage.Practical implicationsSimulations are performed using HSPICE and compared with those performed using the proposed MRTD method for global interconnect length with 130-nm technology, where the computations of the proposed model are carried out using Matlab.Originality/valueThe MRTD method with its unique features is tailored for modelling interconnects. To build further credence to this and its profound existence in the latest state-of-art works, simulations of crosstalk noise and propagation delay, for coupled Cu interconnect lines, using MRTD and finite-difference time-domain (FDTD) are executed. The results illustrated the dominance of MRTD method over FDTD in terms of accuracy.

Simultaneously simulating the scattering properties of nonspherical aerosol particles with different sizes by the MRTD scattering model.

In order to improve the computational efficiency of multi-resolution time domain (MRTD) scattering model, a multi-size synchronous-computational scheme (MSCS) is proposed. By using MSCS, the scattering properties of the particles with different sizes can be simultaneously calculated by MRTD model in one wave-particle interaction simulation. In this model, the pulse plane wave with a wide spectrum is taken as the incident light, and the light scattering simulation for particles with different sizes is transformed into the scattering calculation for a size-fixed particle at different wavelengths. To guarantee the stability and precision of the improved MRTD (IMRTD) model, the method to design model's input parameters, such as the spatial resolution, discrete time interval and pulse width, is proposed. To validate the accuracy of IMRTD model, its results are compared with those of Mie and T-Matrix theory, and the influence of spatial resolution on the precision of IMRTD is analyzed as well. At last, model's computational efficiency is also discussed. The simulation results show that, IMRTD method can calculate the scattering parameters of particles with different sizes simultaneously and accurately, where, in case that the pulse width is 5.56 × 10-8ns, and the radius of the size-fixed particle is 0.5μm (its size parameter is 6.28), light scattering process by particles with size parameters up to 12.56 can be successfully simulated. With the increasing of spatial resolution, the simulation accuracy is improved for all particles, and the improvement for large particles is more notable than that for small ones. It can also be found that the computational efficiency of IMRTD is much higher than that of traditional version.

Application of Convolution Perfectly Matched Layer in MRTD scattering model for non-spherical aerosol particles and its performance analysis

The performance of absorbing boundary condition (ABC) is an important factor influencing the simulation accuracy of MRTD (Multi-Resolution Time-Domain) scattering model for non-spherical aerosol particles. To this end, the Convolution Perfectly Matched Layer (CPML), an excellent ABC in FDTD scheme, is generalized and applied to the MRTD scattering model developed by our team. In this model, the time domain is discretized by exponential differential scheme, and the discretization of space domain is implemented by Galerkin principle. To evaluate the performance of CPML, its simulation results are compared with those of BPML (Berenger's Perfectly Matched Layer) and ADE-PML (Perfectly Matched Layer with Auxiliary Differential Equation) for spherical and non-spherical particles, and their simulation errors are analyzed as well. The simulation results show that, for scattering phase matrices, the performance of CPML is better than that of BPML; the computational accuracy of CPML is comparable to that of ADE-PML on the whole, but at scattering angles where phase matrix elements fluctuate sharply, the performance of CPML is slightly better than that of ADE-PML. After orientation averaging process, the differences among the results of different ABCs are reduced to some extent. It also can be found that ABCs have a much weaker influence on integral scattering parameters (such as extinction and absorption efficiencies) than scattering phase matrices, this phenomenon can be explained by the error averaging process in the numerical volume integration.