Engineered Absorption Enhancement and Induced Transparency in Coupled Molecular and Plasmonic Resonator Systems

• Published in: Nano letters Vol. 13; no. 6; pp. 2584 - 2591
• Main Authors: Adato, Ronen, Artar, Alp, Erramilli, Shyamsunder, Altug, Hatice
• Format: Journal Article
• Language: English
• Published: Washington, DC American Chemical Society 12.06.2013
• Subjects: Analogies; Collective excitations (including excitons, polarons, plasmons and other charge-density excitations); Condensed matter: electronic structure, electrical, magnetic, and optical properties; Condensed matter: structure, mechanical and thermal properties; Coupled modes; Coupling (molecular); Electronic structure and electrical properties of surfaces, interfaces, thin films and low-dimensional structures; Exact sciences and technology; Fullerenes and related materials; Metamaterials; Molecular physics; Nanoscale materials: clusters, nanoparticles, nanotubes, and nanocrystals; Nanostructure; Optical properties and condensed-matter spectroscopy and other interactions of matter with particles and radiation; Physics; Plasmonics; Resonators; Structure of solids and liquids; crystallography; Surface and interface electron states; Visible and ultraviolet spectra; coupling; EIT; Fano resonance; SEIRA; vibrational spectroscopy; Plasmonics; EIA; critical coupling; Damping; External fields; Transparency; Symmetry property; Quantum effect; Quantum interference phenomena; Surface effect; Energy conservation; Experimental design; Plasmons; Resonance; Absorption spectra; Metamaterial; Resonators
• ISSN: 1530-6984; 1530-6992; 1530-6992
• DOI: 10.1021/nl400689q

Coupled plasmonic resonators have become the subject of significant research interest in recent years as they provide a route to dramatically enhanced light-matter interactions. Often, the design of these coupled mode systems draws intuition and inspiration from analogies to atomic and molecular physics systems. In particular, they have been shown to mimic quantum interference effects, such as electromagnetically induced transparency (EIT) and Fano resonances. This analogy also been used to describe the surface-enhanced absorption effect where a plasmonic resonance is coupled to a weak molecular resonance. These important phenomena are typically described using simple driven harmonic (or linear) oscillators (i.e., mass-on-a-spring) coupled to each other. In this work, we demonstrate the importance of an essential interdependence between the rate at which the system can be driven by an external field and its damping rate through radiative loss. This link is required in systems exhibiting time-reversal symmetry and energy conservation. Not only does it ensure an accurate and physically consistent description of resonant systems but leads directly to interesting new effects. Significantly, we demonstrate this dependence to predict a transition between EIT and electromagnetically induced absorption that is solely a function of the ratio of the radiative to intrinsic loss rates in coupled resonator systems. Leveraging the temporal coupled mode theory, we introduce a unique and intuitive picture that accurately describes these effects in coupled plasmonic/molecular and fully plasmonic systems. We demonstrate our approach’s key features and advantages analytically as well as experimentally through surface-enhanced absorption spectroscopy and plasmonic metamaterial applications.