Optically Pumped Lasing Based on Vibrationally Dressed Exciton Polaritons in a Single-Crystal Molecular Cavity at Room Temperature
Takumi Matsuo, Yusuke Ueda, Hitoshi Mizuno, Fumio Sasaki, K. Yamashita, Hisao Yanagi
Abstract
Polaritonic photonics is one of the key technologies for future quantum-based information and communication. Here, we demonstrate strong evidence of vibrationally dressed exciton polaritons formed in a single-crystal planar cavity of 5,5″-bis(biphenylyl)-2,2′:5′,2″-terthiophene (BP3T) at room temperature. Under optical pumping, the BP3T crystals exhibit longitudinal multimode lasing at the primary and secondary vibronic progression bands based on Fabry–Pérot (F-P) resonation between side facets of the planar cavity. Each gain-narrowed vibronic band extraordinarily split into multiple peaks at excitation fluence around the lasing threshold, accompanied with time delay up to several tens of picoseconds, which is unexplainable for conventional photon lasing. Although those lasing characteristics are primarily interpreted as a regime of exciton-polaritons (EPs), the energy versus wavenumber plots of splitting spectra are well-explained by coupling with cooperative vibrations of the ordered BP3T molecules.