Modal approximation for strictly convex plasmonic resonators in the time domain: The Maxwell's equations

We study the possible expansion of electromagnetic field scattered by a strictly convex metallic nanoparticle with dispersive material parameters placed in homogeneous medium low-frequency regime as sum modes oscillating at complex frequencies (diverging infinity), known physics literature quasi-normal expansion. show that such an is valid static and we can approximate electric finite number modes. then use perturbative spectral theory to existence, certain regime, plasmonic resonances poles resolvent for Maxwell's equations non-zero frequency. that, time domain, be written frequencies. introduce renormalised quantities do not diverge exponentially infinity.