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NanoComp / meep

free finite-difference time-domain (FDTD) software for electromagnetic simulations
GNU General Public License v2.0
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Using your own functions to permittivity #2748

Closed leSemaleon closed 9 months ago

leSemaleon commented 9 months ago

Why can you specify your materials only through the Lorentz Drude model? Is this something important? Can I make an artificial material with fixed real and imaginary parts of the permittivity over the entire frequency range?

stevengj commented 9 months ago

No. This is a FAQ.

The problem is that an arbitrary ε(ω) function, e.g. a constant imaginary part, does not correspond in the time domain to a causal, passive material.