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RF-Frequency Modes in Plasmonic Slot Waveguide

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Dear all,

I'm solving for the modes in a plasmonic slot waveguide. The waveguide consists of two gold slabs on silica substrate. The gap is filled with a nonlinear material. Between the air and the two gold slabs there is still a layer filled with the nonlinear material.

I want to solve for modes in the range of 1 GHz up to 1 THz, by using the frequency domain mode analysis. But the solutions look strange, because the modes are fringed (up to the air layer) and there is an electric field change in the air layer.

Does anyone have experience in simulating such problems? Any advice how to do this?

Thank you!

Regards,
David


2 Replies Last Post 05.11.2015, 07:44 GMT-5
Sven Friedel COMSOL Employee

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Posted: 9 years ago 05.11.2015, 07:21 GMT-5
Dear David,

please note that frequency domain theory is a linear theory. As nonlinear materials (nonlinear in their dependence on E) produce second harmonics, not all solution components will vary with one given frequency. Moreover, mode analysis is typically not normalized to a total energy, i.e. using nonlinear materials (in E) would not be reasonable either.

Are you really using nonliner materials (in E) or do you mean material properties that depend on the frequency (or wavelength)?

Best regards,

Sven Friedel
Dear David, please note that frequency domain theory is a linear theory. As nonlinear materials (nonlinear in their dependence on E) produce second harmonics, not all solution components will vary with one given frequency. Moreover, mode analysis is typically not normalized to a total energy, i.e. using nonlinear materials (in E) would not be reasonable either. Are you really using nonliner materials (in E) or do you mean material properties that depend on the frequency (or wavelength)? Best regards, Sven Friedel

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Posted: 9 years ago 05.11.2015, 07:44 GMT-5
Dear Sven,

Thanks answering!

My goal is to describe the Difference-Frequency-Generation in a given Plasmonic Slot Waveguide. The slot is filled with a chromophore such that the chi2 is not anymore negligible.

I want to generate a difference frequency in the range from 1GHz to 1THz. To describe the DFG-Process I need the modes at the respective frequencies. In order to do a accurate mode analysis: What is the permittivity of gold in this low region? Or is a mode analysis not possible anymore?

Best regards,

David
Dear Sven, Thanks answering! My goal is to describe the Difference-Frequency-Generation in a given Plasmonic Slot Waveguide. The slot is filled with a chromophore such that the chi2 is not anymore negligible. I want to generate a difference frequency in the range from 1GHz to 1THz. To describe the DFG-Process I need the modes at the respective frequencies. In order to do a accurate mode analysis: What is the permittivity of gold in this low region? Or is a mode analysis not possible anymore? Best regards, David

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