# I AC/Optical conductivity

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1. Oct 16, 2017

### DeathbyGreen

Maybe someone can help me out; I've been seeing conflicting information on the meaning behind optical conductivity vs AC conductivity. Some papers seem to post plots of transmission and reflectivity, and others a Drude-like $\sigma(\omega)$. In many textbooks I can't seem to find a satisfactory answer.

If we start with a system under a field $E(t) = Ee^{i\omega t}$, solve the Drude model to get $\sigma(\omega)$, is this an expression for optical conductivity or AC? And what are the geometries of both?

2. Oct 17, 2017

### DrDu

I think this depends on frequency (radio- vs. optical).

3. Oct 19, 2017

### Chandra Prayaga

By optical conductivity, do you mean photo-conductivity, which is a material becoming conducting when exposed to light, or do you just mean conductivity at very high frequencies?

4. Oct 20, 2017

### DeathbyGreen

I mean conductivity induced by irradiation; I've seen this called both optical and AC conductivity. Maybe it's just called AC because the light has a frequency and an analogy can be drawn between that and actual AC electricity with connected leads?