At this point, we shortly want to take a look at the impact of the power broadening on the shell permittivity. As directly seen in a comparison between eq 2 and eq 3, the only difference of the permittivities in the classical Lorentz and the HQM model is the additional term Ω 2 in the denominator. Since it does not show up in the imaginary part of the nominator, it cannot be interpreted as a classical damping term. The classical permittivity ϵ class (ω) can be either matched to the real or the imag- inary part of ϵ two-level (ω). Figure exemplifies the situation by comparing the classical and HQM permittivity for the four different Ω that were used to successfully reproduce the experimental data in Figure . To match either the real or the imaginary part of the permittivity of the classical model to the well fitting HQM model, a different choice of the oscillator strength f and damping γ would be required for each Ω (see legend).