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We present a beyond-mean-field approach to predict the nature of organic polariton lasing, accounting for all relevant photon modes in a planar microcavity. Starting from a microscopic picture, we show how lasing can switch between polaritonic states resonant with the maximal gain, and those at the bottom of the polariton dispersion. We show how the population of non-lasing modes can be found, and by using two-time correlations, we show how the photoluminescence spectrum (of both lasing and non-lasing modes) evolves with pumping and coupling strength, confirming recent experimental work on the origin of blueshift for polariton lasing., 6 pages, 4 figures, plus supplemental material

We study two-dimensional charge-imbalanced electron-hole systems embedded in an optical microcavity. We find that strong coupling to photons favors states with pairing at zero or small center of mass momentum, leading to a condensed state with spontaneously broken time-reversal and rotational symmetry, and unpaired carriers that occupy an anisotropic crescent-shaped sliver of momentum space. The crescent state is favoured at moderate charge imbalance, while a Fulde--Ferrel--Larkin--Ovchinnikov-like state --- with pairing at large center of mass momentum --- occurs instead at strong imbalance. The crescent state stability results from long-range Coulomb interactions in combination with extremely long-range photon-mediated interactions., Comment: 6 pages, 4 figures, plus supplemental material

Following experimental realizations of room temperature polariton lasing with organic molecules, we present a microscopic model that allows us to explore the crossover from weak to strong matter-light coupling. We consider a non-equilibrium Dicke-Holstein model, including both strong coupling to vibrational modes and strong matter-light coupling, providing the phase diagram of this model in the thermodynamic limit. We discuss the mechanism of polariton lasing, uncovering a process of self-tuning, and identify the relation and distinction between regular dye lasers and organic polariton lasers., 6 pages, 4 figures, plus supplemental material

The experimental investigations of plasmon-polaritons propagating along the metal surface can be found in numerous published papers. In this paper, the theory of the dispersion of the surface plasmon-polaritons propagating along the surface of metals covered with dielectric resonant thin films, developed in [1] , [2] , [3] , has been made more precise and complete. The calculations presented in this work enable now to evaluate not only the qualitative dependence of the surface plasmon-polaritons splitting value upon the layer thickness l and resonant wavelength λ , but also to determine the numerical value of the gap. The layer thickness l is assumed to be l ⪯i λ and we also assume that the film thickness is much larger than the lattice constant. To demonstrate the results of the theory we consider the plasmon-polariton dispersion relations when metal is covered with the layer comprising molecular J-aggregates.

Strong coupling between cavity photons and molecular vibrations can lead to the formation of vibron-polaritons. In a recent experiment with PVAc molecules in a metal-metal microcavity [A.Shalabney et al., Ang.Chem.Int.Ed. 54 7971 (2015)], such a coupling was observed to enhance the Raman scattering probability by several orders of magnitude. Inspired by this, we theoretically analyze the effect of strong photon-vibron coupling on the Raman scattering amplitude of organic molecules. This problem has recently been addressed in [J.del Pino, J.Feist and F.J.Garcia-Vidal; J.Phys.Chem.C 119 29132 (2015)] using exact numerics for a small number of molecules. In this paper we derive compact analytic results for any number of molecules, also including the ultra-strong coupling regime. Our calculations predict a division of the Raman signal into upper and lower polariton modes,with some enhancement to the lower polariton Raman amplitude due to the mode softening under strong coupling., 11 pages, 4 figures