Guillet, Thierry, Li, Feng, Orosz, Laurent, Kamoun, Olfa, Bouchoule, Sophie, Brimont, Christelle, Disseix, Pierre, Lafosse, Xavier, Leroux, Mathieu, Leymarie, Joël, Malpuech, Guillaume, Mexis, Meletios, Mihailovic, Martine, Patriarche, Gilles, Réveret, François, Solnyshkov, Dimitri, Zúñiga-Pérez, Jesús, Laboratoire Charles Coulomb (L2C), Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS), Centre de recherche sur l'hétéroepitaxie et ses applications (CRHEA), Université Nice Sophia Antipolis (1965 - 2019) (UNS), COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Centre National de la Recherche Scientifique (CNRS)-Université Côte d'Azur (UCA), Laboratoire des sciences et matériaux pour l'électronique et d'automatique (LASMEA), Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Centre National de la Recherche Scientifique (CNRS), Laboratoire de photonique et de nanostructures (LPN), Centre National de la Recherche Scientifique (CNRS), European Project: 235114,EC:FP7:PEOPLE,FP7-PEOPLE-ITN-2008,CLERMONT4(2009), Université Nice Sophia Antipolis (... - 2019) (UNS), Guillet, Thierry, and Exciton-polaritons in microcavities: physics and devices - CLERMONT4 - - EC:FP7:PEOPLE2009-09-01 - 2013-08-31 - 235114 - VALID
International audience; ZnO is a wide bandgap semiconductor with strong excitonic properties, in particular a large oscillator strength and a large exciton binding energy. It therefore raises a strong interest for the generation and control of polariton condensates up to room temperature. We have recently reported the condensation of polaritons in a bulk ZnO microcavity over an unprecedented range of exciton-photon compositions and of temperatures, up to room temperature [1]. The complete phase diagram of the ZnO polariton laser has been measured (cf figure 1a), showing that its threshold is only 6 times larger at 300 K than at 8 K. It is in a good qualitative agreement with the simulations of exciton and polariton relaxation in a kinetic model (figure 1b). Strongly excitonic (96% exciton fraction) as well as strongly photonic condensates (83% photon fraction) are realized (figure 1c). Moreover imaging of the condensate allows to evidence in-plane free propagation of the polariton condensate starting from the excitation spot. This tunability is obtained on a fully-hybrid microcavity with a high quality factor (Q>2000) and a large Rabi splitting (250 meV); it represents an important progress compared to our previous demonstration of a ZnO polariton laser in a Q=450 microcavity [2], as well as to other recent reports [3]. It also confers a strong advantage to ZnO microcavities compared to GaN [4], since strong excitonic condensates can here be investigated. Figure 1. (a) Detuning dependence of the polariton condensation threshold for a 2.5 polariton branch, under quasi-continuous excitation; (b) Polariton density at the condensation threshold deduced from the kinetic model; (c) Angle-resolved emission below and above threshold (T=300K, almost zero detuning). The authors acknowledge financial support from FP7 program through ITN networks CLERMONT4 (235114) and SPIN-OPTRONICS (237252). References [1] F. Li et al., Phys. Rev. Lett. 110, 196406 (2013) [2] T. Guillet et al., Appl. Phys. Lett. 98, 211105 (2011) [3] H. Franke et al., New J. Phys. 14, 013037 (2012); T.C. Lu et al., Optics Express 20, 5530 (2012) [4] J. Levrat et al., Phys. Rev. B 81, 125305 (2010)