Numerically such a propagation is achieved via combining finite-difference time-domain (FDTD) methodology for Maxwell's equations ( ) with the split-operator propagation of the Schrodinger equations (6). In general, full three-dimensional calculations are extremely memory and time consuming. While three dimensional calculations can be made more efficient by 3D domain decomposition parallelization, this work considers a one-dimensional optical cavity as schematically depicted in Fig. . The cavity is formed by two parallel golden plates. The electrodynamics of the cavity follows the Maxwell equations ( ) that, for the chosen geometry, reduce to (9) where it is assumed that the cavity size is significantly smaller compared to its transverse directions (i.e., all spatial dependencies of the electromagnetic field with respect to x and y are neglected). The macroscopic polarization inside the metal is simulated using the conventional Drude model 34 (10) with parameters describing gold: eV and eV. The molecular part of the model (6) retains only and the corresponding matrix elements . Results reported in this manuscript pertain to the cavity driven by the CW field at normal incidence propagating along z from right to left, i.e., exciting the right metal plate first. By adjusting plates' thickness and the cavity size (distance between plates) we can tune the fundamental cavity mode to a desired frequency. We note that the thickness of the plates controls how much electromagnetic energy can penetrate the cavity and remain inside at resonant conditions. The thickness also influences the cavity losses, which include two channels -radiation to the far field and Ohmic losses in the metal. Eqs. ( ) and ( ) are discretized in space and time following the FDTD approach. To simulate an open system, we enclose the