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Finding epsilon_r in the Drude-Lorentz model

Posted Aug 6, 2018, 9:59 p.m. EDT Version 5.2 2 Replies

Larnii Booth
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Hi,

I am calculating plasmonic resonance of gold nanoparticles (a bow tie-shaped structure, with light enhancement occuring between the two triangles that make up the bow tie).

I want to calculate the mode volume, and need the permittivty of the gold to do so, which in this case is frequency dependent (at visible wavelength).

I am using the Drude Lorentz model in the optics package. It calculates the frequency-dependent permittivity epsilon_r.

How can I make COMSOL tell me this value?

Thank you for your help, and sorry if this is an obvious question.

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2 Replies Last Post Aug 8, 2018, 12:19 a.m. EDT
Ulf Olin COMSOL Employee

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Posted: 6 years ago Aug 7, 2018, 10:24 a.m. EDT
Updated: 6 years ago Aug 7, 2018, 10:30 a.m. EDT

Hi,

There is a variable for the relative permittivity that you can use. It is called tag.epsilonrxx, where tag is the tag of your physics interface, for instance emw for the Electromagnetic Waves, Frequency Domain interface in the RF Module. This variable is defined based on your input parameters for the Drude-Lorentz model.

Best regards,
Ulf

Hi, There is a variable for the relative permittivity that you can use. It is called tag.epsilonrxx, where tag is the tag of your physics interface, for instance emw for the Electromagnetic Waves, Frequency Domain interface in the RF Module. This variable is defined based on your input parameters for the Drude-Lorentz model. Best regards, Ulf
Larnii Booth
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Posted: 6 years ago Aug 8, 2018, 12:19 a.m. EDT

Hi Ulf,

Thank you very much for your reply. The variable works. It gave a complex relative permittivity as expected.

Larnii

Hi Ulf, Thank you very much for your reply. The variable works. It gave a complex relative permittivity as expected. Larnii

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