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fancompute / legume

🌱 Guided-mode expansion of photonic crystal slabs
https://legume.readthedocs.io/
MIT License
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questions about the dielectric constant setup #61

Closed HenryTang0127 closed 4 months ago

HenryTang0127 commented 4 months ago

I noticed that the data type of your model is float, in some special cases, dielectric constant is complex, which means there is some loss in the material (such as metal). So, are there methods to apply the imaginary part dielectric constant into Legume model? Is it possible to calculate a PhC slab with loss? Thank you!

momchilmm commented 4 months ago

Unfortunately no, legume currently only accepts real permittivity. There are various complications with lossy modes, specifically with properly ortho normalizing the basis set.

I think what you may have seen as complex is the Fourier transform of the permittivity. For a real valued field this is still complex, but has the property that e(G) = e(-G)*

HenryTang0127 commented 4 months ago

Thank you for your reply! What I want to do is to calculate the band stucture of a PhC slab with loss, which means the permittivity has imagniary part. I will find other ways to do ti.Thank you again.