1. The nature of light-matter interaction:
re-radiation of the electrons driven by the field.

2. + = Classical light-matter interaction
Bound-electron: the oscillator model
Motion of the “spring” (polarization)
In phase with the force (E-field)
Below resonance: “index of refraction” + =
Time P
Time

3. + = + = Classical light-matter interaction
Bound-electron: the oscillator model
Field of radiating electron
Below resonance: “index of refraction”
At resonance: “absorption”
Time P + = + =
Time P
Time

4. + = + = Classical light-matter interaction
“Free”-electron: the Drude model (plasma)
Below resonance: “index of refraction”
Time P + =
At resonance: “absorption”
“Negative index of refraction” + =
Time P
Time

5. The Drude Dude is not always applicable
The plasma frequency defined by
represent a real frequency:
the frequency for density fluctuations of electrons (see homework)
The characteristic period is ps
The Drude model is isotropic. At l> 800 nm, the ionization is anisotropic (tunnel)
With dude Drude, no difference between linear and circular polarization.
The error in the classical derivation:
Taking the ε out of the time derivative is not always the right approach.