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Modeling 2D Gaussian beam

Posted Aug 21, 2015, 3:24 p.m. EDT Wave Optics Version 5.1 1 Reply

Li-Fan Yang
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Hi,

I am encountering a problem when simulating a Gaussian beam in 2D system. I use the built-in model in Comsol from background field implementation and self-defined Gaussian profile but just the same as the built-in equation. The computational domain is surrounded by perfect matched layers.

It looks fine when the material is vacuum or air, but goes very weird when changing the material from air to water. It has clear fringe, looks like interference or reflection, on the Gaussian beam itself but it should not be.

Do anyone encounter the same problem or can answer the question when simulating Gaussian beam in non-air material?

Thanks,
Li-Fan
1 Reply Last Post Oct 27, 2015, 9:41 a.m. EDT
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Hello Li-Fan Yang

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Taha Benyattou
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Posted: 9 years ago Oct 27, 2015, 9:41 a.m. EDT
The fringes that appears in your simulation are related to the wave number k used by default by comsol (k is set to ewfd.k0). This parameter is set for propagation within the vacuum. If, the propagation occurs in a medium with a refactive index n0, set the wavenumber parameter k to ewfd.k0*n0 and the fringes will disappear.
T. Benyattou
The fringes that appears in your simulation are related to the wave number k used by default by comsol (k is set to ewfd.k0). This parameter is set for propagation within the vacuum. If, the propagation occurs in a medium with a refactive index n0, set the wavenumber parameter k to ewfd.k0*n0 and the fringes will disappear. T. Benyattou

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