Strong Coupling and Laser Action of Ladder‐Type Oligo( p ‐phenylene)s in a Microcavity

We investigate the coupling of ladder‐type quarterphenyl to the photon modes of a dielectric ZrO x /SiO x microcavity at ultraviolet wavelengths. For a relatively long cavity (≈10 μm) with high‐reflectivity mirrors (0.998), optically pumped laser action is demonstrated in the weak‐coupling regime. We observe single‐mode operation with a threshold of 0.4 mJ cm −2 . Strong coupling is achieved by using a short λ /2 cavity. We find pronounced anti‐crossing features of the molecular (0,0) and (0,1) vibronic transitions and the cavity mode in angle‐dependent reflectivity measurements providing Rabi splittings of (90±10) meV. All these features occur spectrally resonant to the exciton transition of ZnO demonstrating the potential of ladder‐type oligo( p ‐phenylene)s for the construction of inorganic/organic hybrid microcavities.