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How to define frequency/wavelength dependent refractive index of gold in COMSOL 5.1?

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I want to simulate the scattering through nanodisc of gold for that i have to assigned the refractive index of gold as a function of wavelength.

How can we assign it in COMSOL 5.1 ?

2 Replies Last Post 18.09.2016, 14:24 GMT-4
Daniel Smith COMSOL Employee

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Posted: 9 years ago 06.07.2015, 08:59 GMT-4
Hi Jalpa, you can use the new Optical material library which was added in V5.1. Simply go to Add Material>Optical>Inorganic Materials>Au (...). There are several different entries for gold. All entries have the real and imaginary part of the refractive index as a function of wavelength.

The Optical material library requires either the Ray Optics Module or Wave Optics Module.
Hi Jalpa, you can use the new Optical material library which was added in V5.1. Simply go to Add Material>Optical>Inorganic Materials>Au (...). There are several different entries for gold. All entries have the real and imaginary part of the refractive index as a function of wavelength. The Optical material library requires either the Ray Optics Module or Wave Optics Module.

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Posted: 8 years ago 18.09.2016, 14:24 GMT-4
Hi Daniel,

I think you can help me for which I am struggling for so long.

I am simulating a gold antenna in RF time domain. My operating frequency is 100 THz or above. In this case, the permittivity (frequency-dependent) of the gold antenna becomes complex valued.

The complex valued permittivity of gold at THz regime,

eps=-eps_real+eps_imag

My problem is how can I define negative real permittivity in time domain ? If I put negative real number in the permittivity then this gives be unrealistic results.

I would like to know what is the approach to define negative complex valued permittivity of metals (gold, copper) in Comsol TIME DOMAIN Module.

Please kindly let me know or refer me to some other resources which can be helpful to implement in Comsol.

Thanks,
Rishad
Hi Daniel, I think you can help me for which I am struggling for so long. I am simulating a gold antenna in RF time domain. My operating frequency is 100 THz or above. In this case, the permittivity (frequency-dependent) of the gold antenna becomes complex valued. The complex valued permittivity of gold at THz regime, eps=-eps_real+eps_imag My problem is how can I define negative real permittivity in time domain ? If I put negative real number in the permittivity then this gives be unrealistic results. I would like to know what is the approach to define negative complex valued permittivity of metals (gold, copper) in Comsol TIME DOMAIN Module. Please kindly let me know or refer me to some other resources which can be helpful to implement in Comsol. Thanks, Rishad

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