Drude-like dielectric function

Theoretical modelling shows that this configuration is more favourable for the achievement of a full photonic band-gap, provided that there is a dielectric contrast of at least 2.8 [30]. This requirement is hard to achieve, and it has only been reported for silicon [31] and germanium [32] inverse opals. An alternative can be the use of metals with a Drude-like behavior of the dielectric function. When the dielectric contrast of the photonic crystal becomes extremely... 

Despite of its simplicity the Drude model correctly describes the optical properties of simple metals. In Fig. 1.4 we report the experimental dielectric constant, the refractive index and the reflectance for aluminum. Figure 1.4 closely resembles Fig. 1.3 with (Op 15 eV. The best agreement of the dielectric function of metal with that obtained in the framework of the free electron model can be obtained for the alkali metals (Li, Na, K, Cs, Rb), whose response seems to be weakly affected by the contribution from the core electrons. Notably, alkali metals, such as sodium, have an almost free-electron-like response and thus, in accordance... 

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