Tuning Vibrational Strong Coupling with Co-Resonators

Strong coupling of molecular vibrations to optical resonances is a promising route toward photonic control over chemical reactions. Due to their narrow line widths and close energy proximity, vibrational transitions afford intriguing opportunities for strong coupling of multiple matter states with the same optical state to form polaritons with significant hybridization. Solutions of three organometallic ions were used to control the number, energy, and intensity of molecular resonances in a 200 cm(-1) window, allowing for a systematic investigation of the formation of three, four, and five polaritons. The presence of additional molecules simultaneously coupled to an optical mode did not significantly affect the Rabi splitting energy of a given molecular resonance, but did substantially alter the Hopfield mixing coefficients of the resulting polaritons. The introduction of a co-resonator is therefore an alternative means for the modification of the properties of polaritons.