Figure shows the permittivity of the six metals from UV-visible to mid-infrared. Although the data in the 1000-1700 nm range are missing, the Drude-Lorenz model obtained a smooth and continous permittivity over the entire measurement range from 200 to 2 × 10 4 nm by fitting via the least-squares method over the entire measurement range. With Lorenz model over the full measurement range, we obtained permittivity from 200 nm to 2 × 10 4 nm over this wide spectral window. Figure also shows plots of the first three terms (Eqn. 1) of the Drude-Lorenz equation used in the analysis, and Lorenz terms separately. Note that ε ∞ is a constant term that should be included in the Drude and Lorenz terms independently. However, for analytical reasons, it is difficult to separate them; therefore, it was treated as a single constant. The results show that the permittivity of HEA is closer to those of Pd and Pt than those of Au, Ag, and Cu. However, as shown in the imaginary part of the Lorentz model, the loss-related contributions are smaller than those of Pt and Pd. Table lists parameters obtained from the analysis using the Drude-Lorentz model for the experimentally measured permittivity and extracted via fit. As mentioned above, ε ∞ is We confirmed that fixing these parameters to, for example, the ideal metal permittivity did not significantly affect the analytical results.