Figure 4.

Dispersion relations for electromagnetic (EM) waves propagating along the metal-dielectric interface for metals of properties represented by various models of the dielectric functions. Blue lines represent the dispersion relations $Re{k}_{\Vert }\left(\omega \right)$ (Equation (4)), (a) and $Rek\left(\omega \right)$ (Equation (14)) (b) found for ${\epsilon }_m\left(\omega \right)$ which accounts for ohmic losses and frequency dependent interband transitions in gold (left column) and silver (right column).