Light-responsive organic polaritons from first principles

Controlling the optical properties of light-responsive organic molecules is essential for their application in photonics. We demonstrate how light-responsive organic polaritons formed inside an optical cavity can be used to modify these properties based on first principles. Specifically, we study the excited state properties of the trans-azobenzene molecule and the free base tetraphenyl porphyrin (H₂TPP) molecule under weak to strong light-matter coupling. Our results show that the cavity can modulate the dispersion and absorption properties of organic molecules. Compared to the case outside the cavity, the anomalous dispersion of the trans-azobenzene molecule inside the cavity is suppressed and this suppression decreases with increasing coupling strength, showing the potential of strong light-matter coupling in manipulating the optical dipole trap of organic molecules. Moreover, by adjusting the cavity parameters to tune the strength of the light-matter coupling, we achieve free switching between symmetric Lorentz and asymmetric Fano line shapes for H₂TPP polaritonic excitations. During the switching between these spectral features, we also find that the cavity can be used to control the spontaneous radiation of organic molecules via the Purcell effect. These findings provide a new pathway to manipulate the optical properties of light-responsive organic molecules.