다중혈관 관상동맥 환자에서 y-문합을 이용하여 양쪽 내흉동맥만을 사용한 우회술의 조기 성적

Numerical Initial Value Problems in Ordinary Differential Equations

Using the finite-difference time-domain method, we show that the plasmons of a nanostar result from hybridization of plasmons of the core and tips of the nanoparticle. The nanostar core serves as a nanoscale antenna, dramatically increasing the excitation cross section and the electromagnetic field enhancements of the tip plasmons. Our analysis demonstrates that the plasmon hybridization picture can be combined with numerical approaches to interpret the physical origin of the plasmons of highly complex nanostructures.

Plasmon resonances of a gold nanostar.

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Power Electronics Converters Applications And Design

Metallic nanostructures now play an important role in many applications. In particular, for the emerging fields of plasmonics and nanophotonics, the ability to engineer metals on nanometric scales allows the development of new devices and the study of exciting physics. This review focuses on top-down nanofabrication techniques for engineering metallic nanostructures, along with computational and experimental characterization techniques. A variety of current and emerging applications are also covered.

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Engineering metallic nanostructures for plasmonics and nanophotonics

We perform a simple sensitivity analysis of a W1 waveguide bend in a photonic crystal (PhC) where we use the information obtained to optimize the PhC bend's frequency response. Within a single optimization step we already achieve very low power reflection coefficients over almost the entire frequency range of the photonic bandgap (PBG), i.e., an achromatic bend. A further analysis shows that there is a single critical rod in the optimized bend structure that exhibits an extraordinary high sensitivity at a given frequency. Hence power reflection becomes tunable from 0 % up to 100 % involving only small changes in the critical rod's properties. This opens the door to novel topologies for compact switches and sensor applications.

Design and optimization of an achromatic photonic crystal bend.

Numerical simulations of plasmonic structures are very demanding and expensive in terms of memory and CPU time, making the selection of a suitable numerical method for the field computation important. To examine this problem, we applied several numerical methods to a group of 2D plasmonic nanowire problems. In particular, we examine the Finite Element Method (FEM) and the Finite Difference Time-Domain (FDTD) method from the family of domain-discretization methods. We also look at the Multiple Multipole Program (MMP), the Method of Auxiliary Sources (MAS), and the Mesh-less Boundary Integral Equation (BIE) method from the family of boundary-discretization methods. We quantitatively compare several results generated from each method to make some conclusions about their applicability and accuracy for plasmonic simulations. Domain-discretization methods (FEM and FDTD) can reach a high level of accuracy only with a high discretization. This is affordable on modern computer hardware in 2D. Recommendations for improving this are provided. The boundary-discretization techniques have a clear advantage in terms of speed, matrix size, and accuracy in 2D. This advantage may disappear in the full 3D analysis of geometrically complicated structures. This happens because matrices become denser or more ill-conditioned. Therefore the most efficient method depends on the problem dimension and complexity.

Comparison of Numerical Methods for the Analysis of Plasmonic Structures

We report on the numerical structural optimization of two-dimensional photonic crystal (PhC) power dividers by using two different classes of optimization algorithms, namely, a modified truncated Newton (TN) gradient search as deterministic local optimization scheme and an evolutionary optimization representing the probabilistic global search strategies. Because of the severe accuracy requirements during optimization, the proper PhC device has been simulated by using the multiple-multipole program that is contained in the MaX-1 software package. With both optimizer classes, we found reliable and promising solutions that provide vanishing power reflection and perfect power balance at any specified frequency within the photonic bandgap. This outcome is astonishing in light of the discrete nature inherent in the underlying PhC structure, especially when the optimizer is allowed to intervene only within a very small volume of the device. Even under such limiting constraints structural optimization is not only feasible but has proven to be highly successful.

Optimization of photonic crystal structures

We propose a general design methodology for photonic crystal (PhC) diplexers, which is carried out along a filtering T-junction. The diplexer operation is investigated while carefully analyzing the dispersion relations of the three different waveguide channels. All simulations are carried out using the multiple multipole method (MMP), which offers perfect excitation and matching conditions for all waveguide ports involved. The resulting diplexer is highly compact (it covers an area of 13 x 9 lattice constants) and simple when compared to other PhC diplexer designs.

On the design of photonic crystal multiplexers

This paper presents: 1) a novel method for accurate high-frequency modeling of dry-type transformer windings based on magnetic and electric field simulations for parameter extraction of the detailed equivalent circuit of the entire winding system; 2) a method for fast and accurate transient solution of the circuit differential equations that describe the voltage distribution over the winding system; 3) an efficient, cheap, and nondestructive low-voltage measurement system based on a self-developed lightning-impulse generator; and 4) verification of the simulation results by comparison with measurement.

Jasmin Smajic

Papers

Design and optimization of an achromatic photonic crystal bend.

Comparison of Numerical Methods for the Analysis of Plasmonic Structures

Optimization of photonic crystal structures

On the design of photonic crystal multiplexers

Simulation and Measurement of Lightning-Impulse Voltage Distributions Over Transformer Windings