The Plasma (Drude) Material Model and some corrections to the model

trobertstroberts Ansys Employee Posts: 11

The Plasma model, or more commonly called Drude model is a simple, and widely used analytical expression for to describe the optical properties of materials with free charge carriers. Particularly metallic substance such as Au, Ag and some alloys.

Lumerical’s material database offers several models from different references, and we encourage users to apply these widely cited models. However if users want to use analytical expression for some materials with the Drude model, they will need to find those parameters:

ε: permittivity
ωP: plasma resonance in units of rad/s
νC: plasma collision in units of rad/s


Please note that such a model is most accurate in a narrow-band around the plasma resonance, since other physical phenomenon become important further from the resonance. For examples, the values at visible light range will not be the same as middle infrared. This page tabulates a list of metals and their plasma resonance/collision data, but without specifying the applied wavelength range, so use them with caution.

Due to the power, accuracy and simplicity of this model many groups have extended it to more accurately account for other effects such as.

  • Very small enough nanoparticles.

Surface Plasmons and Nonlocality: A Simple Model, Physical Review Letters – 26 Aug 13

  • Some have applied quantum-corrected models:

Bridging quantum and classical plasmonics with a quantum-corrected model, Nature Communications -  08 May 12

  • And their are many other examples where this model has been used, and extended to include additional physics.


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