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Pokročilé simulace fotonických struktur metodou FDTD / Pokročilé simulace fotonických struktur metodou FDTDVozda, Vojtěch January 2015 (has links)
Finite-Difference Time-Domain method (FDTD) is based on numerical solution of Maxwell's equations, nowadays widely used for simulating optical response of photonic structures. This paper provides brief introduction to the FDTD method and several important extensions which make the basic code much more versatile. In order to broaden analysis of photonic structures, transfer matrix method (TMM) is also involved. The code is firstly tested using simple model structures which optical response might be compared with different numerical or even analytical approaches. Debugged code is used to improve photonic crystals for enhanced sensitivity of biosensing devices based on refractive index changes of sensed medium. Last but not the least, properties (sensitivity and Q-factor of resonant peak) of holey waveguide are investigated in one-, two- and three-dimensional simulation. It is shown here, that even this simple structure may compete with complex photonic crystals in the field of biosensors. Powered by TCPDF (www.tcpdf.org)
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Finite-Difference Time-Domain (FDTD) Modeling of Nanoscale Plasmonic Substrates for Surface-Enhanced Raman Spectroscopy (SERS)Gorunmez, Zohre 19 November 2019 (has links)
No description available.
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Computation of Electromagnetic Fields in Assemblages of Biological Cells using a Modified Finite-Difference Time-Domain SchemeAbd-Alhameed, Raed, Excell, Peter S., See, Chan H. January 2007 (has links)
Yes / When modeling objects that are small compared with the wavelength, e.g., biological cells at radio frequencies, the standard finite-difference time-domain (FDTD) method requires extremely small time-step sizes, which may lead to excessive computation times. The problem can be overcome by implementing a quasi-static approximate version of FDTD based on transferring the working frequency to a higher frequency and scaling back to the frequency of interest after the field has been computed. An approach to modeling and analysis of biological cells, incorporating a generic lumped-element membrane model, is presented here. Since the external medium of the biological cell is lossy material, a modified Berenger absorbing boundary condition is used to truncate the computation grid. Linear assemblages of cells are investigated and then Floquet periodic boundary conditions are imposed to imitate the effect of periodic replication of the assemblages. Thus, the analysis of a large structure of cells is made more computationally efficient than the modeling of the entire structure. The total fields of the simulated structures are shown to give reasonable and stable results at 900,1800, and 2450 MHz. This method will facilitate deeper investigation of the phenomena in the interaction between electromagnetic fields and biological systems.
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Modeling Harmonic Generation from Nanostructured SurfacesThompson, Jesse 05 December 2022 (has links)
In this thesis, I develop a novel time-domain approach for nonlinear scattering theory (NLST), a previously frequency domain method for estimating the nonlinear generation from a nanostructure. Due to a gap in literature, I then perform a full comparison of this novel time domain approach to the existing one in the frequency domain. Using the example scenario of third harmonic generation from various media in 1D and 3D, I compare - quantitatively - the NLST estimated nonlinear spectra to two types of direct nonlinear simulations: one using an experimental value for the nonlinear optical susceptibility, and, for plasmonic systems, another using a hydrodynamics model for the nonlinear plasmonic response. Through testing differing NLST approaches on these systems, I demonstrate the effectiveness of the novel time-domain NLST and assess the use cases for this method as well as the pre-existing ones. Lastly, I discuss the applicability of NLST in future works involving the inverse design process, and high-order harmonic generation.
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Numerical Modeling and Inverse Design of Complex Nanophotonic SystemsBaxter, Joshua Stuart Johannes 10 January 2024 (has links)
Nanophotonics is the study and technological application of the interaction of electromagnetic waves (light) and matter at the nanometer scale. The field's extensive research focuses on generating, detecting, and controlling light using nanoscale features such as nanoparticles, waveguides, resonators, nanoantennas, and more. Exploration in the field is highly dependent on computational methods, which simulate how light will interact with matter in specific situations. However, as nanophotonics advances, so must the computational techniques. In this thesis, I present my work in various numerical studies in nanophotonics, sorted into three categories; plasmonics, inverse design, and deep learning. In plasmonics, I have developed methods for solving advanced material models (including nonlinearities) for small metallic and epsilon-near-zero features and validated them with other theoretical and experimental results. For inverse design, I introduce new methods for designing optical pulse shapes and metalenses for focusing high-harmonic generation. Finally, I used deep learning to model plasmonic colour generation from structured metal surfaces and to predict plasmonic nanoparticle multipolar responses.
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Analytical Path to Improved RF Field Homogeneity for High Field MRIChen, Xin 19 March 2009 (has links)
No description available.
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Modeling the Behavior of Gold Nanoparticles and Semiconductor Nanowires for Utilization in Nanodevice ApplicationsMakepeace, Andrew W. 21 August 2013 (has links)
No description available.
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Development of hybrid explicit/implicit and adaptive h and p refinement for the finite element time domain methodSrisukh, Yudhapoom 06 January 2006 (has links)
No description available.
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SIMULATION OF OPTICAL DEVICES AND CIRCUITS USING TIME DOMAIN METHODSHan, Lin 04 1900 (has links)
<p>A new model, referred to as the Rational Dispersion Model is proposed for modeling of dispersive materials in wide wavelength range using the Finite-Difference Time-Domain(FDTD) method. A hardware-accelerated FDTD method combined with the matrix pencil method is proposed to solve both guided and leaky modes. A circuit model based on the complex mode theory is proposed for analysis of large scale structures with non-negligible radiation effects.</p> / Doctor of Philosophy (PhD)
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SELF-ADJOINT S-PARAMETER SENSITIVITY ANALYSIS WITH FINITE-DIFFERENCE TIME-DOMAIN (FDTD) METHODLi, Yan 06 1900 (has links)
<p> This thesis contributes to the development of a novel electromagnetic (EM) time-domain computational approach, the self-adjoint variable method, for the scattering parameter (S-parameter) sensitivity analysis of high frequency problems. </p> <p> The design sensitivity analysis provides sensitivity information in the form of the response gradient (response Jacobian). For that, various techniques are used, ranging from finite-difference approximations to quadratic and spline interpolations. However, when the number of design parameters becomes large, the simulation time would become unaffordable, which is especially the case with EM simulations. The proposed self-adjoint sensitivity analysis (SASA) approach aims at providing sensitivity information efficiently without sacrificing the accuracy. Its efficiency lies in the fact that regardless of the number of design parameters, only one simulation of the original structure is required- the one used to compute the S-parameters. Thus, the sensitivity computation has negligible overhead. At the same time, it has second-order accuracy. </p> <p> Currently, commercial EM simulators provide only specific engineering responses, such as Z- or S-parameters. No sensitivity information is actually made available. With the SASA approach, the only requirement for the EM solver is the ability to access the field solution at the perturbation grid points. This feature is generally available with all time-domain EM simulators. The manipulation of the field solutions in this approach is simple and it adds practically negligible overhead to the -simulation time. </p> <p> We confirm the validity of this approach for both the shape and constitutive parameters of the design structures. 2-D examples including metallic and dielectric details are presented, using the field solutions from an in-house time-domain solver. We also explore the feasibility of implementing this approach with one of the commercial solvers, XFDTD v. 6.3. </p> <p> Suggestions for future research are provided. </P> / Thesis / Master of Applied Science (MASc)
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