Browsing by Author "Loke, Vincent L. Y."

Now showing 1 - 5 of 5

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Comparison between discrete dipole approximation and other modelling methods for the plasmonic response of gold nanospheres
(Springer Science+Business Media, 2014-05) Loke, Vincent L. Y.; Huda, G. M.; Donev, E. U.; Schmidt, V.; Hastings, J. T.; Mengüç, Mustafa Pınar; Wriedt, T.; Mechanical Engineering; MENGÜÇ, Mustafa Pınar
We investigate the plasmonic response of gold nanospheres calculated using discrete dipole approximation validated against the results from other discretization methods, namely the finite-difference time-domain method and the finite-element methods. Comparisons are also made with calculations from analytical methods such as the Mie solution and the null-field method with discrete sources. We consider the nanoparticle interacting with the incident field both in free space and sitting on a planar substrate. In the latter case, discrete dipole approximation with surface interaction is used; this includes the interaction with the 'image dipoles' using Sommerfeld integration.
Open Access
Discrete dipole approximation of gold nanospheres on substrates: considerations and comparison with other discretization methods
(AAPP Physical, Mathematical, and Natural Sciences, 2011) Loke, Vincent L. Y.; Donev, E. U.; Huda, G. M.; Hastings, J. T.; Mengüç, Mustafa Pınar; Wriedt, T.; Mechanical Engineering; MENGÜÇ, Mustafa Pınar
We embark on this preliminary study of the suitability of the discrete dipole approximation with surface interaction (DDA-SI) method to model electric field scattering from noble metal nano-structures on dielectric substrates. The refractive index of noble metals, particularly due to their high imaginary components, require smaller lattice spacings and are especially sensitve to the shape integrity and volume of the model. The results of DDA-SI model are validated against those of the well-established finite element method (FEM) and the finite difference time domain (FDTD) method.
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Discrete-dipole approximation with surface interaction: computational toolbox for MATLAB
(Elsevier, 2011-07) Loke, Vincent L. Y.; Mengüç, Mustafa Pınar; Nieminen, T. A.; Mechanical Engineering; LOKE, Vincent L. Y.; MENGÜÇ, Mustafa Pınar
We describe a MATLAB toolbox that utilizes the discrete-dipole approximation (DDA) method for modelling light interaction with arbitrarily-shape scatterers in free space as well with planar surface interaction (DDA-SI). The range of applicable models range from optical micromanipulation, plamonics, nano-antennae, near-field coupling and general light interaction with scatterers ranging from a few nanometers to several microns in size.
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Surface waves and atomic force microscope probe-particle near-field coupling: discrete dipole approximation with surface interaction
(Optics InfoBase, 2010-10) Loke, Vincent L. Y.; Mengüç, Mustafa Pınar; Mechanical Engineering; LOKE, Vincent L. Y.; MENGÜÇ, Mustafa Pınar
Evanescent waves on a surface form due to the collective motion of charges within the medium. They do not carry any energy away from the surface and decay exponentially as a function of the distance. However, if there is any object within the evanescent ﬁeld, electromagnetic energy within the medium is tunneled away and either absorbed or scattered. In this case, the absorption is localized, and potentially it can be used for selective diagnosis or nanopatterning applications. On the other hand, scattering of evanescent waves can be employed for characterization of nanoscale structures and particles on the surface. In this paper we present a numerical methodology to study the physics of such absorption and scattering mechanisms. We developed a MATLAB implementation of discrete dipole approximation with surface interaction (DDA-SI) in combinationwith evanescent wave illumination to investigate the near-ﬁeld coupling between particles on the surface and a probe. This method can be used to explore the effects of a number of physical, geometrical, and materialproperties for problems involving nanostructures on or in the proximity of a substrate under arbitrary illumination.
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T-matrix method for modelling optical tweezers
(Taylor & Francis, 2011) Nieminen, T. A.; Loke, Vincent L. Y.; Stilgoe, A. B; Heckenberg, N. R.; Rubinsztein-Dunlop, H.; Mechanical Engineering; LOKE, Vincent L. Y.
We review the use of the T-matrix description of scattering, or the T-matrix method, for the calculation of optical forces and torques, especially for the computational modelling of optical tweezers. We consider both simple particles such as homogeneous isotropic spheres, spherical shells, spheroids, and so on, and complex particles, including anisotropic particles, inhomogenous particles, and geometrically complex particles.