We study the temperature-dependent optical properties of gold over a broad
energy spectrum covering photon energies below and above the interband
threshold. We apply a semi-analytical Drude-Lorentz model with
temperature-dependent oscillator parameters. Our approximations are based on
the distribution of electrons over the active bands with a density of states
provided by density functional theory. This model can be easily adapted to
other materials with similar band structures and can also be applied to the
case of occupational nonequilibrium. Our calculations show a strong enhancement
of the intraband response with increasing electron temperature while the
interband component decreases. Moreover, our model compares well with density
functional theory-based calculations for the reflectivity of highly excited
gold and reproduces many of its key features. Applying our methods to thin
films shows a sensitive nonlinear dependence of the reflection and absorption
on the electron temperature. These features are more prominent at small photon
energies and can be highlighted with polarized light. Our findings offer
valuable insights for modeling ultrafast processes, in particular, the pathways
of energy deposition in laser-excited samples