The discrete dipole approximation: An overview and recent developments

Yurkin, Maxim A.; Hoekstra, Alfons G.

doi:10.1016/j.jqsrt.2007.01.034

Cited by 773 publications

(477 citation statements)

References 138 publications

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“…For spherical particles function f is given by the Mie theory. For non-spherical particles the function is more complex and several methods such as the Discrete Dipole Approximation can be employed (Yurkin and Hoekstra, 2007). The GRIMM Spectrometer model EDM 164 employed in the present work uses multi-channel light scattering optics as the measuring principle; a detailed description with schematic diagrams of a similar instrument can be found in Grimm and Eatough (2009).…”

Section: The Grimm Aerosol Optical Spectrometermentioning

confidence: 99%

Seasonal variability of aerosol concentration and size distribution in Cape Verde using a continuous aerosol optical spectrometer

Pio

Cardoso

Cerqueira

et al. 2014

Front. Environ. Sci.

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One year of, almost continuous, measurements of aerosol optical properties and chemical composition were performed at the outskirts of Praia, Santiago Island, Cape Verde, within the framework of CV-DUST (Atmospheric aerosol in Cape Verde region: seasonal evaluation of composition, sources and transport) research project, during 2011. This article reports the aerosol number and mass concentration measurements using a GRIMM Optical Aerosol Spectrometer that provides number size discrimination into 31 size ranges from 0.25 to 32 μm. Time series of 5 min average PM 10 concentrations revealed peak values higher than 1000 μg.m −3 during winter dust storm events originating over Northern Africa. The 24 h average concentrations exceeded the World Health Organization (WHO) guidelines for PM 2.5 and PM 10 in 20 and 30% of the 2001 days, respectively. Annual average mass concentrations (±standard deviation) for PM 1 , PM 2.5 , and PM 10 were 5 ± 5, 19 ± 21, and 48 ± 64 μg.m −3 , respectively. The annual PM 2.5 and PM 10 values were also above the limits prescribed by the WHO (10 and 20 μg.m −3 , respectively). The aerosol mass size distribution revealed two main modes for particles smaller than 10 μm: a fine mode (0.7-0.8 μm), which possibly results of gas to particle conversion processes; and a coarse mode with maxima at 3-4 μm, which is associated with desert dust and sea salt sources. Within the coarse mode two sub-modes with maxima at 5-6 and 10-12 μm were frequently present.

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Section: The Grimm Aerosol Optical Spectrometermentioning

confidence: 99%

Seasonal variability of aerosol concentration and size distribution in Cape Verde using a continuous aerosol optical spectrometer

Pio

Cardoso

Cerqueira

et al. 2014

Front. Environ. Sci.

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“…3 shows that there is no response to a field parallel to the plates, and the parallel components of the permeability therefore take the value 1; thus we need only deal with the perpendicular component,  perp , which significantly reduces the complexity of the problem. We applied the discrete dipole approximation 13 to derive the total moment and demagnetization factor as a function of  perp for our sample geometries.…”

Section: mentioning

confidence: 99%

A d.c. magnetic metamaterial

et al. 2008

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Electromagnetic metamaterials 1 are a class of materials which have been artificially structured on a subwavelength scale. They are currently the focus of a great deal of interest because they allow access to previously unrealisable properties like a negative refractive index 2 . Most metamaterial designs have so far been based on resonant elements, like split rings 3 , and research has concentrated on microwave frequencies and above. In this work, we present the first experimental realisation of a non-resonant metamaterial designed to operate at zero frequency. Our samples are based on a recently-proposed template 4 for an anisotropic magnetic metamaterial consisting of an array of superconducting plates. Magnetometry experiments show a strong, adjustable diamagnetic response when a field is applied perpendicular to the plates. We have calculated the corresponding effective permeability, which agrees well with theoretical predictions. Applications for this metamaterial may include non-intrusive screening of weak DC magnetic fields. The first metamaterials 3,5 were designed to operate at microwave frequencies. Since then, while there has been some research on radio-frequency metamaterials 6 , most of the research effort has been focused on higher frequencies: technologically-important microwaves or visible light 7 . The low-frequency end of the spectrum has remained relatively unexplored. In addition, the majority of metamaterials devised to date consist of an arrangement of resonant components. There is a good reason for this: the response of a resonator varies greatly as a function of the frequency at which it is being driven. Close to the resonant frequency, the amplitude of the response can be very large, while the phase changes. The range of available values of the response function, or susceptibility, is therefore very wide. One of the crowning achievements of (and driving forces behind) metamaterials research is the realization of a negative refractive index 2,8 , and a simple argument shows that this cannot be achieved without relying on resonant structures. However, the price of working close to the resonant frequency is that losses and frequency dispersion are greatest here. When a negative response is not required then a non-resonant structure is advantageous. Another recent development means that there is new demand for metamaterials with nonnegative anisotropic parameters. Transformation optics 9 is a design paradigm that allows a new level of control over electromagnetic fields. For a given design, it provides a recipe for the material parameters as a function of position. The parameters generated in this way are always non-negative and anisotropic. A spectacular demonstration of the technique was provided by the construction of an electromagnetic cloak 10 using metamaterials. The interior of the cloak is shielded from microwaves with minimal disruption to the exterior fields.

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“…In order to compute the Green's tensors Gðr; r; ωÞ for the waveguide geometries, we adapt the discrete dipole approximation (DDA) [37,38]. The key idea behind DDA is to discretize only those parts of the system that differ from a background, i.e., free space or a planar substrate, with a known analytic solution.…”

Section: B Potential Simulationsmentioning

confidence: 99%

Coupling Thermal Atomic Vapor to Slot Waveguides

et al. 2018

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We study the interaction of thermal rubidium atoms with the guided mode of slot waveguides integrated in a vapor cell. Slot waveguides provide strong confinement of the light field in an area that overlaps with the atomic vapor. We investigate the transmission of the atomic cladding waveguides depending on the slot width, which determines the fraction of transmitted light power interacting with the atomic vapor. An elaborate simulation method has been developed to understand the behavior of the measured spectra. This model is based on individual trajectories of the atoms and includes both line shifts and decay rates due to atom-surface interactions that we have calculated for our specific geometries using the discrete dipole approximation. Furthermore, we investigate density-dependent effects on the line widths and line shifts of the rubidium atoms in the subwavelength interaction region of a slot waveguide.

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The discrete dipole approximation: An overview and recent developments

Cited by 773 publications

References 138 publications

Seasonal variability of aerosol concentration and size distribution in Cape Verde using a continuous aerosol optical spectrometer

Seasonal variability of aerosol concentration and size distribution in Cape Verde using a continuous aerosol optical spectrometer

A d.c. magnetic metamaterial

Coupling Thermal Atomic Vapor to Slot Waveguides

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