Near-Field Gain and Far-Field Control via a Plasmonic Time Crystal Slab

Light-matter interactions can be substantially altered in the presence of time-varying media. We study the interaction between a harmonic electric dipole and a plasmonic time crystal slab. Temporal modulation of the plasma frequency enables near-field gain, allowing the dipole to absorb rather than emit energy, suppressing nonradiative losses. At the parametric resonance condition, the slab radiates strongly to the far field, producing 100% oscillations in the radiated power at distances up to 10^{3} times the ε-near-zero wavelength. These findings reveal a new mechanism for controlling light-matter interaction in time-varying plasmonic systems.