The Experts below are selected from a list of 114 Experts worldwide ranked by ideXlab platform

Guobin Ren - One of the best experts on this subject based on the ideXlab platform.

  • A generalized 2D FDTD model for photonic crystal fibers with frequency dependent media
    Optical and Quantum Electronics, 2007
    Co-Authors: Guobin Ren, G. Wang, P. P. Shum, K. T. V. Grattan, T. Sun
    Abstract:

    A generalized model based on the two-dimensional finite-difference time-domain (2D FDTD) method for photonic crystal fibers (PCF) with frequency dependent media is presented. The Maxwell’s curl equations are formulated using flux density and the magnetic field. Auxiliary differential equations are used with Complex-Conjugate Pole-residue pairs which incorporate the material dispersion of the dispersive media. The model is demonstrated to be a unified approach for arbitrary dispersive materials; therefore, it definitely reduces implementation cost when dealing with different frequency-dependent materials.

  • A compact 2D finite-difference time-domain method for full-vectorial analyses of photonic crystal fibers with material dispersion
    Journal of Optoelectronics and Advanced Materials, 2007
    Co-Authors: Ping Shum, Guobin Ren
    Abstract:

    We present a compact 2D finite-difference time-domain full-vectorial method by reformulating the time dependent Maxwell's curl equations with electric flux density and magnetic field intensity, with auxiliary differential equations using Complex-Conjugate Pole-residue pairs. The model is general and robust to treat general frequency-dependent material and it can be easily extended for nonlinearity analysis. As an example, the Sellmeier equation is implicitly incorporated as a special case of the general formulation to account for material dispersion of fused silica. The correlation results match well with multiPole method. The relative error is within 0.02%.

  • Generalized Finite-Difference Time-Domain Method Utilizing Auxiliary Differential Equations for the Full-Vectorial Analysis of Photonic Crystal Fibers
    IEEE Photonics Technology Letters, 2007
    Co-Authors: Ping Shum, Guobin Ren
    Abstract:

    We present the generalized finite-difference time-domain full-vectorial method by reformulating the time-dependent Maxwell's curl equations with electric flux density and magnetic field intensity, with auxiliary differential equations using Complex-Conjugate Pole-residue pairs. The model is generic and robust to treat general frequency-dependent material and nonlinear material. The Sellmeier equation is implicitly incorporated as a special case of the general formulation to account for material dispersion of fused silica. The results are in good agreement with the results from the multiPole method. Kerr nonlinearity is also incorporated in the model and demonstrated. Nonlinear solutions are provided for a one ring photonic crystal fiber as an example.

Bruno Palpant - One of the best experts on this subject based on the ideXlab platform.

  • Complex-Conjugate Pole-residue Pair-Based FDTD Method for Assessing Ultrafast Transient Plasmonic Near Field
    Plasmonics, 2020
    Co-Authors: Tadele Orbula Otomalo, Fabrice Mayran De Chamisso, Bruno Palpant
    Abstract:

    The study of the optical properties of plasmonic nanostructures in the stationary regime has greatly benefited from the development of numerical methods, among which Finite Difference Time Domain (FDTD) is popular. In contrast, the use of these numerical tools for assessing the transient plasmonic optical response triggered by ultrashort laser pulses is hampered by the difficulty to address small variations of the material optical properties with reasonable computational time. Yet, many of the developments based on this ultrashort response rely on the dynamics of the near-field topography around the nanostructures. In this article, we present a way to bridge this gap with the Complex-Conjugate Pole-residue pair (CCPRP) approach. A CCPRP-based FDTD simulator has been developed. First, a simple methodology to check the end-to-end accuracy of the FDTD simulation is provided. Then, in conjunction with a three-temperature model, the approach enables us to calculate the ultrafast transient near field inside and around a gold nanoparticle (AuNP) upon absorption of a subpicosecond laser pulse. The transient variation of the field intensity inside and around the AuNP is compared with the one determined by the Mie theory. The dependence of the transient field intensity on the distance away from the nanoparticle surface and on the delay time after laser pulse absorption is finally analyzed.

Guangxu Shen - One of the best experts on this subject based on the ideXlab platform.

  • Internal Network Boundary Condition Incorporated in TLM for Efficiently Modeling Thin Layer of Periodic Structures
    IEEE Transactions on Microwave Theory and Techniques, 2016
    Co-Authors: Ying Xiong, Wenquan Che, Desong Wang, Guangxu Shen
    Abstract:

    It is a problem when modeling the thin layer of periodic structures with numerical method by directly discretizing the inner part, because the fine mesh applied to simulate the thin layer would result in great computational data. The internal network boundary condition (INBC) incorporated in the transmission line matrix (TLM) scheme is proposed in this paper, to avoid the directly discretization of the thin layer and achieve a high accuracy. The thin layer of periodic structure is regarded as an easily analyzed two-port network. Vector fitting approach is used to approximate the network parameters into a series of rational expressions with either real term or Complex Conjugate Pole–residue pairs. The INBC equation with discrete-time form is derived and then incorporated in TLM scheme by introducing the approximate Pole–residue pairs to the TLM update equation. Compared with the extremely fine-discretized TLM unit cell used to deal with the thin layer by the conventional TLM scheme, a much larger coarse TLM unit cell is accurate enough to be used to discretize the structure by the proposed method. Compared with the conventional TLM scheme, substantial savings in computational storage are achieved. A common frequency selective surface (FSS) structure is first analyzed for the validation of the method. Good agreement in scattering characteristics is observed in frequency domain between the proposed method and simulation by HFSS software. To further demonstrate the validity of the proposed method, an aperture-coupled resonator-based FSS is designed and fabricated. Good agreement among the S-parameters from the proposed method, simulation, and measurement is observed, verifying the accuracy of the proposed method.

Ping Shum - One of the best experts on this subject based on the ideXlab platform.

  • A compact 2D finite-difference time-domain method for full-vectorial analyses of photonic crystal fibers with material dispersion
    Journal of Optoelectronics and Advanced Materials, 2007
    Co-Authors: Ping Shum, Guobin Ren
    Abstract:

    We present a compact 2D finite-difference time-domain full-vectorial method by reformulating the time dependent Maxwell's curl equations with electric flux density and magnetic field intensity, with auxiliary differential equations using Complex-Conjugate Pole-residue pairs. The model is general and robust to treat general frequency-dependent material and it can be easily extended for nonlinearity analysis. As an example, the Sellmeier equation is implicitly incorporated as a special case of the general formulation to account for material dispersion of fused silica. The correlation results match well with multiPole method. The relative error is within 0.02%.

  • Generalized Finite-Difference Time-Domain Method Utilizing Auxiliary Differential Equations for the Full-Vectorial Analysis of Photonic Crystal Fibers
    IEEE Photonics Technology Letters, 2007
    Co-Authors: Ping Shum, Guobin Ren
    Abstract:

    We present the generalized finite-difference time-domain full-vectorial method by reformulating the time-dependent Maxwell's curl equations with electric flux density and magnetic field intensity, with auxiliary differential equations using Complex-Conjugate Pole-residue pairs. The model is generic and robust to treat general frequency-dependent material and nonlinear material. The Sellmeier equation is implicitly incorporated as a special case of the general formulation to account for material dispersion of fused silica. The results are in good agreement with the results from the multiPole method. Kerr nonlinearity is also incorporated in the model and demonstrated. Nonlinear solutions are provided for a one ring photonic crystal fiber as an example.

Tadele Orbula Otomalo - One of the best experts on this subject based on the ideXlab platform.

  • Complex-Conjugate Pole-residue Pair-Based FDTD Method for Assessing Ultrafast Transient Plasmonic Near Field
    Plasmonics, 2020
    Co-Authors: Tadele Orbula Otomalo, Fabrice Mayran De Chamisso, Bruno Palpant
    Abstract:

    The study of the optical properties of plasmonic nanostructures in the stationary regime has greatly benefited from the development of numerical methods, among which Finite Difference Time Domain (FDTD) is popular. In contrast, the use of these numerical tools for assessing the transient plasmonic optical response triggered by ultrashort laser pulses is hampered by the difficulty to address small variations of the material optical properties with reasonable computational time. Yet, many of the developments based on this ultrashort response rely on the dynamics of the near-field topography around the nanostructures. In this article, we present a way to bridge this gap with the Complex-Conjugate Pole-residue pair (CCPRP) approach. A CCPRP-based FDTD simulator has been developed. First, a simple methodology to check the end-to-end accuracy of the FDTD simulation is provided. Then, in conjunction with a three-temperature model, the approach enables us to calculate the ultrafast transient near field inside and around a gold nanoparticle (AuNP) upon absorption of a subpicosecond laser pulse. The transient variation of the field intensity inside and around the AuNP is compared with the one determined by the Mie theory. The dependence of the transient field intensity on the distance away from the nanoparticle surface and on the delay time after laser pulse absorption is finally analyzed.