We present measurements on plasmonic metamolecules under local excitation using cathodoluminescence which show a spatial redistribution of the local density of optical states at the same frequency where a sharp spectral Fano feature in extinction has been observed. Our analytical model shows that both nearand far-field effects arise due to interference of the same two eigenmodes of the system. We present quantitative insights both in a bare state, and in a dressed state picture that describe Fano interference either as near-field amplitude transfer between coupled bare states, or as interference of uncoupled eigenmodes in the far field. We identify the same eigenmode causing a dip in extinction to strongly enhance the radiative local density of optical states, making it a promising candidate for spontaneous emission control.

Phys. Rev. Lett.
Resonant Nanophotonics

Frimmer, M., Coenen, T., & Koenderink, F. (2012). Signature of a Fano Resonance in a plasmonic metamolecule's local density of optical states. Phys.Rev.Lett., 108(Article number: 77404), 1–5. doi:10.1103/PhysRevLett.108.077404