Control of the Stokes Shift with Strong Coupling

Abstract

Strong coupling of excitons in macroscopic ensembles of quantum emitters and cavities (or surface plasmons) can lead to dramatic change of the optical properties and modification of the dispersion curves, characterized by the normal mode splitting of the order of 1 eV. Such gigantic alteration of the hybrid energy states enables scores of unparalleled physical phenomena and functionalities, ranging from enhancement of electrical conductivity to control of chemical reactions. While coupling of single emitters to a cavity is a pure quantum mechanical phenomenon, the origin of the strong coupling involving large ensembles of molecules is the subject of controversy. In this work, the strong coupling of rhodamine 6G dye molecules with silver Fabry–Perot cavities is studied and the significant increase of the Stokes shift between the excitation and the emission bands of hybridized molecules is demonstrated. The proposed empirical model of the underlying physics calls for the quantum mechanical parity selection rule.