Strong Coupling of Molecular Absorption and Mid-Infrared Metamaterial Resonances

Here we present numerical, analytical, and experimental evidence for strong optical coupling between a mid-infrared perfect absorber thin-film metamaterial and a molecular absorption resonance within a dielectric medium. Clear anti-crossing behavior is exhibited numerically and experimentally when the metamaterial resonance is scanned through the dielectric molecular resonance; a coupled oscillator model is used to present a further analytical description. The anti-crossing is used to demonstrate and quantify the strength of the optical coupling within the thin film. Such a device can potentially be developed for mid-infrared sensing applications and actively tunable metamaterial optical components.