Implementation of the critical points model in a SFM-FDTD code working in oblique incidence

Hamidi, Mahdi; Baida, Fadi; Belkhir, Abderrahmane; Lamrous, Omar

doi:10.1088/0022-3727/44/24/245101

Cited by 23 publications

(10 citation statements)

References 16 publications

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“…The code takes into account the periodicity of the structure in x and y directions via Bloch's boundary conditions [43] and the upper and lower semi-infinite media in z direction through perfectly matched layer (PML) conditions of Berenger [44]. The implemented Critical Points Drude model [45] deals with the dispersive nature of gold and ITO using different fitted parameters to match experimental values. The structure is illuminated, with a plane wave, at normal incidence from the substrate.…”

Section: Methodsmentioning

confidence: 99%

Surface Enhanced Raman Scattering on Regular Arrays of Gold Nanostructures: Impact of Long-Range Interactions and the Surrounding Medium

et al. 2020

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Long-range interaction in regular metallic nanostructure arrays can provide the possibility to manipulate their optical properties, governed by the excitation of localized surface plasmon (LSP) resonances. When assembling the nanoparticles in an array, interactions between nanoparticles can result in a strong electromagnetic coupling for specific grating constants. Such a grating effect leads to narrow LSP peaks due to the emergence of new radiative orders in the plane of the substrate, and thus, an important improvement of the intensity of the local electric field. In this work, we report on the optical study of LSP modes supported by square arrays of gold nanodiscs deposited on an indium tin oxyde (ITO) coated glass substrate, and its impact on the surface enhanced Raman scattering (SERS) of a molecular adsorbate, the mercapto benzoic acid (4-MBA). We estimated the Raman gain of these molecules, by varying the grating constant and the refractive index of the surrounding medium of the superstrate, from an asymmetric medium (air) to a symmetric one (oil). We show that the Raman gain can be improved with one order of magnitude in a symmetric medium compared to SERS experiments in air, by considering the appropriate grating constant. Our experimental results are supported by FDTD calculations, and confirm the importance of the grating effect in the design of SERS substrates.

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Section: Methodsmentioning

confidence: 99%

Surface Enhanced Raman Scattering on Regular Arrays of Gold Nanostructures: Impact of Long-Range Interactions and the Surrounding Medium

et al. 2020

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“…The main object studied in this paper is two-dimensional SFM-FDTD, its algorithm prototype can refer to the Ref. [5,6,[8][9][10][11] . Some transformations are made on the original Maxwell equations and overcoming the time bias generated from the time-frequency conversion under oblique incidence [8] .…”

Section: Theory Of Sfm-fdtdmentioning

confidence: 99%

Study the ISO-FDTD algorithm to processing higher-order dielectric function in SFM-FDTD

Xie

Yang

2022

Preprint

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In this paper, we use an ISO-FDTD (improved shift operator finite-difference time-domain, proposed by others) algorithm to further process some more complex dielectric functions like critical models, and several higher order Lorentz models fitted by ourselves, these function models totally have 6 ~ 8 susceptibility terms, and each term was consisted by two complex poles (Lorentz model). Our working supporting the universal applicability of ISO-FDTD for processing higher-order complex dispersive materials. And we applied this ISO-FDTD algorithm in SFM-FDTD (split-field method FDTD) to simulate dispersion media under oblique incidence. The simulation results meet well with the analytical solutions. Researchers can have an alternate option besides ADE and PLRC methods when processing high-order dispersive media in SFM-FDTD.

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“…6b and their values are given in the caption. The glass substrate optical refractive index is fixed to n s = 1.458 and the dispersion of the silver film is described through a Drude-Critical Points (DCP) model [35] which has been adapted to the studied spectral range (λ ∈[600 nm,1400 nm]).…”

Section: Appendix B: Optimization Of the Geometrymentioning

confidence: 99%

Contactless optical spinning tweezers with tunable rotation frequency

Hameed¹,

Zeghdoudi²,

Guichardaz³

et al. 2021

Preprint

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Advances in optical trapping design principles have led to tremendous progress in manipulating nanoparticles (NPs) with diverse functionalities in different environments using bulky systems. However, efficient control and manipulation of NPs in harsh environments require a careful design of contactless optical tweezers. Here, we propose a simple design of a fibered optical probe allowing the trapping of dielectric NPs in a contactless regime as well as a transfer of the angular momentum of light to the NP inducing its mechanical rotation. A polarization conversion from linear (guided fundamental mode) to circular one is provoked geometrically by breaking the cylindrical symmetry of a coaxial nano-aperture that is engraved at the apex of a tapered metal coated optical fiber. Numerical simulations show that this simple geometry tip allows powerful light transmission with efficient polarization conversion. This guarantees a very stable trapping in non-contact regime together with potentially highly tunable positive or negative rotation frequencies (up to 45 Hz in water and 5.3 MHz in air for 10 mW injected 1 power in the fiber). This type of fiber probe opens the way to a new generation of miniaturized tools for total manipulation (trapping, sorting, spinning) of NPs.

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Implementation of the critical points model in a SFM-FDTD code working in oblique incidence

Cited by 23 publications

References 16 publications

Surface Enhanced Raman Scattering on Regular Arrays of Gold Nanostructures: Impact of Long-Range Interactions and the Surrounding Medium

Surface Enhanced Raman Scattering on Regular Arrays of Gold Nanostructures: Impact of Long-Range Interactions and the Surrounding Medium

Study the ISO-FDTD algorithm to processing higher-order dielectric function in SFM-FDTD

Contactless optical spinning tweezers with tunable rotation frequency

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