Collective Resonances in gold nanoparticles arrays

[Laux]

Hi everyone,

I’m trying to reproduce the results found in a paper to verify my OptiFDTD settings.
http://journals.aps.org/prl/pdf/10.1103/PhysRevLett.101.143902
I entered the settings described Figure 4
Gold nanorods 123x85x35 (nm)
Pitch of the array 540 nm (between the centers)
Homogeneous index n=1.46

On my curves, the positions of the diffractive orders are correct (~560 nm for <1,1> and ~790 nm for <1,0>)
My curves show the coupling between the LSPR and the Rayleigh anomalies but it looks like the LSPR is strongly redshifted by 200 nm !

This is my first utilisation of FDTD and I can’t find the reason of this shift, if anyone could check the settings in my design, it would help me a lot.

[Aurelien Duval]

Hi,

Thanks for trying OptiFDTD. A shift in resonances is likely to be due to a difference in defining the material model. We use a Lorentz-Drude fit on data from Rakic et.al “optical properties of metallic Films for vertical-cavity optoelectronic devices”, Applied Optics, Aug, 1998, Vol. 37, N0.22, pp.5272. There’s a least 4-5 sources in the litterature for gold.

Unfortunately I don’t have access to the article you mention. If you can send me a copy, I will be happy to try and see if we can reproduce the results.

Aurelien

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