Figure 4

Estimations of dynamic changes of the optical properties upon irradiation of Ti (a) and Mo (b) by a 213 fs laser pulse at λ = 1030 nm. Variations of the real and imaginary parts of the dielectric permittivity ε and the associated SPP decay length are shown at different laser fluences (colored lines with increasing fluence from right to left): 0.1, 0.2, 0.4, 0.6, 1.0 and 1.5 J/cm2 for titanium and 0.1, 0.2, 0.4, 0.69, 1.0 and 1.5 J/cm2 for molybdenum. In each graph, the green solid line corresponds to the experimental fluence (averaged over the irradiation spot) at which the reported LIPSS were produced.