CPM Seminar

Organic polariton lasers: quantum fluids of light

Stéphane Kéna-Cohen

École Polytechnique

All of the optical processes we are familiar with: absorption, emission and the scattering of light can be understood by assuming that the incident light does not significantly modify the underlying molecular electronic states. The extreme case where light-matter interaction is so strong that it must be treated non-pertubatively has been termed the strong-coupling regime. Polaritons, the resulting mixed light-matter particles, can then exhibit a number of unique phenomena. We will describe how these quasiparticles can be exploited to enhance the photoluminescence quantum yield of emitters, realize low-threshold lasing[1] and create room-temperature analogs to Bose-Einstein condensates[2]. In particular, we will describe recent experiments with organic microcavities containing the oligomer 2,7-bis[9,9-di(4-methylphenyl)-fluoren-2-yl]-9,9-di(4-methylphenyl)fluorene that show fascinating phenomenology such as the spontaneous formation of vortices, dynamic instabilities, repulsive interactions between polaritons and excitons and polariton flow for distances of up to 20 \μm: orders of magnitude longer than the exciton diffusion length.[2,3]

References
[1] Kéna-Cohen S., Forrest S.R., Room-temperature polariton lasing in an organic single-crystal microcavity, Nature Photonics, 4, (2010), p. 371.
[2] Daskalakis K.D., Maier S.A., Murray R., Kéna-Cohen S. Nonlinear interactions in an organic polariton condensate, Nature Materials, 13, (2014), p. 271.
[3] Daskalakis K.D., Maier S.A, Kéna-Cohen S. Spatial coherence and stability in a disordered organic polariton condensate, Phys. Rev. Lett., 115, (2015), p. 035301