Béatrice Dagens

Integrated plasmonic nanotweezers for nanoparticle manipulation

We numerically demonstrate that short gold nanoparticle chains coupled to traditional SOI waveguides allow conceiving surface plasmon-based nanotweezers. This configuration provides for jumpless control of the trapping position of a nano-object as a function of the excitation wavelength, allowing for linear repositioning. This novel feature can be captivating for the conception of compact integrated optomechanical nanoactuators.

Plasmonic nanotweezers composed by a gold dimer for ultra-effective nanoparticles trapping

A plasmonic nanotweezers based on the coupling between a gold dimer and a SOI waveguide is here numerically investigated. By optimizing the dimer gap size, an ultra-high value of the stiffness is achieved.

Ultra-efficient nanoparticle trapping by integrated plasmonic dimers

We numerically demonstrate that gold dimers coupled with a silicon-on-insulator waveguide enable an efficient plasmonic tweezing of dielectric nanobeads, having radii down to 50xa0nm. By means of a rigorous 3D finite difference time domain and simplified gradient force-based calculations, we investigate the effect of the gap size involved on the tweezing action. We also demonstrate that the scattering force helps the trapping in the proximity of the dimer, thanks to the establishment of light vortices.

Strong coupling and vortexes assisted slow light in plasmonic chain-SOI waveguide systems

A strong coupling regime is demonstrated at near infrared between metallic nanoparticle chains (MNP), supporting localized surface plasmons (LSP), and dielectric waveguides (DWGs) having different core materials. MNP chains are deposited on the top of these waveguides in such a way that the two guiding structures are in direct contact with each other. The strong coupling regime implies (i) a strong interpenetration of the bare modes forming two distinct supermodes and (ii) a large power overlap up to the impossibility to distinguish the power quota inside each bare structure. Additionally, since the system involves LSPs, (i) such a strong coupling occurs on a broad band and (ii) the peculiar vortex-like propagation mechanism of the optical power, supported by the MNP chain, leads to a regime where the light is slowed down over a wide wavelength range. Finally, the strong coupling allows the formation of guided supermodes in regions where the bare modes cannot be both guided at the same time. In other words, very high k modes can then be propagated in a dielectric photonic circuit thanks to hybridisation, leading to extremely concentrated propagating wave. Experimental work gives indirect proof of strong coupling regime whatever the waveguide core indexes.

Integrated plasmonic nanoantenna for out-of-plane beam steering

We numerically study the giant coupling between a Si3N4 waveguide and a silver nanoparticle chain at visible wavelengths and the resulting integrated nanoantenna showing tunable out-of-plane beaming in both angle and intensity.

Design of metallic nanoparticle gratings for filtering properties in the visible spectrum

Plasmonic resonances in metallic nanoparticles are exploited to create efficient optical filtering functions. A finite element method is used to model metallic nanoparticle gratings. The accuracy of this method is shown by comparing numerical results with measurements on a two-dimensional grating of gold nanocylinders with an elliptic cross section. A parametric analysis is then performed in order to design efficient filters with polarization dependent properties together with high transparency over the visible range. The behavior of nanoparticle gratings is also modeled using the Maxwell-Garnett homogenization theory and analyzed by comparison with the diffraction of a single nanoparticle. The proposed structures are intended to be included in optical systems that could find innovative applications.