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Gaussian beam illuminated on thin films

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Hi, I got a question about setting gaussian beam in the wave-optical module.

My structure composes of a thin Fe layer (5 nm) on the SiO2 substrate, laser wavelength 800 nm.

The COMSOL tutorial "Nanorod" shows we can directly set the gaussian beam conveniently using the scattering wave formulation, and surrounding PML are adopted to absorb any reflection.

However, I am not sure if this method is correct since my structure is not a isolated scatter, but a large thin film, and I am sure how to set gaussian beam in the port function.

Any suggestions are quite welcome.


1 Reply Last Post Jan 13, 2020, 4:53 a.m. EST
Lars Dammann COMSOL Employee

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Posted: 5 years ago Jan 13, 2020, 4:53 a.m. EST

Hi Song Sun,

strictly speaking, the background field formulation is only valid for isolated scatterers. It does not work for infinite substrates.

You could use the scattering boundary condition instead. Since version 5.5 it is possible to define an incoming wave in the shape of a gaussian beam on those.

Best wishes, Lars Drögemüller

Hi Song Sun, strictly speaking, the background field formulation is only valid for isolated scatterers. It does not work for infinite substrates. You could use the scattering boundary condition instead. Since version 5.5 it is possible to define an incoming wave in the shape of a gaussian beam on those. Best wishes, Lars Drögemüller

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