We theoretically investigate interacting dark resonances in a plasmonic meta-molecule comprising a bright nano-antenna coupled to cascaded dark elements. This structure enables efficient energy transfer and exhibits sub-natural spectral response analogous to the atomic counterpart.
Detection and sensing of molecules via their interaction with light opens opportunities for studies ranging from nanoscale single-molecule readout to long-range experiments. Plasmonic antennas allow localized electromagnetic enhancement, allowing Raman-spectroscopic sensing with sub-nanometer spatial resolution. Further signal enhancement can be obtained through the use of molecular coherence - produced either through coherent Raman excitation or via direct infrared driving. The next level of improvements in signal-to-noise ratio will come with the use of properly engineered non-classical states of light.
The self-consistent model of coupled Maxwell-Liouville-von Neumann equations is used to scrutinize nonlinear dynamics of nano-materials comprised of interacting quantum emitters and plasmons. It is shown that ultra-short resonant laser pulses significantly modify optical properties of such hybrid systems. It is demonstrated that the energy transfer between interacting molecules and plasmons occurs on a femtosecond time scale. This energy transfer can be controlled with both materials parameters and laser radiation.