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Compositional arrangement of rod/shell nanoparticles: an approach to provide efficient plasmon waveguides

Ahmadivand A., Golmohammadi S.

Opto-Electronics Review

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2014

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Vol. 22, No. 2

101-108

EN

In this work, we investigated the optical properties of a novel compositional configuration of gold nanorod and silver nanoshell which is embedded in a SiO₂ substance. The proper geometrical sizes for compositional rod/shell arrangement have been obtained based on the position and peak of plasmon resonance at λ~1550 nm. Adjusting the plasmon resonance position at declared spectrum helps us to provide an arrangement which shows high efficiency and minimum losses. The influence of destructive components such as internal damping and scattering on the rod/shell combination is demonstrated by corresponding diagrams. Moreover, we proposed a nano-array based on examined configuration and the quality of light transmission along the array is studied. We figured out and depicted optical properties of the array such as transmission loss factors, group velocities, transmitted power, transmission quality, and two-dimensional snapshots of surface plasmons (Sps) coupling between nanoparticles arrangements under transverse and longitudinal modes excitations. Ultimately, it is shown that the suggested nanostructure based on studied nanoparticles configuration has a potential to utilize in designing nanophotonic devices such as splitters, couplers, and routers. Finite-difference time-domain method (FDTD) as a major simulation model has been employed to study the features of the waveguide.

2

Analysis of the arm spacing effect on symmetric and asymmetric Y-shape optical power splitters: plasmonic interactions between gold nanorings

Ahmadivand A.

Optica Applicata

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2014

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Vol. 44, nr 1

123--133

EN

In this paper, we investigated specific properties and features of several kinds of Y-splitters based on gold nanorings arrays which are surrounded by SiO2 host substance, to be used at C-band spectrum (λ ~ 1550 nm). The comparison between two kinds of splitters shows that the symmetric splitter demonstrates better performance than the asymmetric splitter at given wavelength with high efficiency and transmittance (power ratio). Calculations proved that the transmitted power percentage was approximately ~47.5% in the well-organized splitter. It is shown that the offset distance plays an important role in the quality of the optical energy division and transmission through the plasmonic waveguide. The influence of increasing and decreasing in the offset distance was demonstrated numerically by snapshots. Hence, choosing and determining the appropriate value for the offset distance lead to the structure with lower losses and higher percentage in energy transmission. Ultimately, the optical behavior of an asymmetric nanostructure with unequal distances between the arms and the main array is investigated and its applications and possible purposes are introduced.

3

Routing properties of the T-structure based on Au/SiO2 nanorings in optical nanophotonic devices

Ahmadivand A.

Optica Applicata

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2012

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Vol. 42, nr 3

659-666

EN

In the present paper, we have utilized Au nanoring arrays in an SiO2 host to provide a T-structure for the purpose of routing and switching optical energy in optical integrated devices to operate at optical communication band (? ? 1550 nm). To employ this router at spectral region considered, localized surface plasmons resonance (LSPR) must be red-shifted around 1550 nm. This T-shaped router includes Au nanorings with a 175 nm inner diameter, a 35 nm thickness and a 35 nm height, and the intercenter distance between two nanorings is 330 nm. To demonstrate the routing properties, we utilized the finite-difference time-domain (FDTD) method. It is shown that the non-straight chain can transport and route the optical energy with certain velocity of light and transmission coefficient. In addition, the percentage of transmitted or power ratio for this structure has been calculated as almost 90%. The optical energy transport can take place at group velocity of approximately 25% of the velocity of light (0.25c0, where c0 is the velocity of light in the vacuum). The router based on nanoring chains shows better performance in switching and transporting the optical energy in comparison to other nanoparticles (nanospheres, nanodisks and nanorods).