Résumé
Spatial observation and optical manipulation of polariton quantum liquids are raising a large interest in the studies of polariton condensates in microcavities [1]. In this work, we report the study of polariton condensates in a semi-hybrid ZnO microcavity where the condensation of polaritons up to room temperature has been achieved. This cavity is based on high quality AlN/AlGaN DBRs on 200µm ∗ 200µm mesas. The obtention of a low condensation threshold in a microcavity is related to its local quality factor Q. However the generation of the condensate also strongly depends on the photonic disorderof the cavity i.e. on polariton localization. The purpose of this work is to demonstrate the influence of this last parameter using different large excitation shapes. Figure 1.a shows a cross sectional energy mapping below threshold of polaritons at negative detuning. It is done by scanning the sample with a focused CW excitation spot. The energy fluctuation is less than 4 meV and the local quality factor is above 1900. We then excite the sample with large excitation areas. The photoluminescence profile created by an elongated excitation (60µm ∗ 5µm) is shown on figure 1.b. The intensity profile indicates that the polariton condensate is not uniform. In fact we can clearly see the localization of polaritons on sitesthat can be separated by more than 10 µm . We assume that this effect is related to the photonic disorder. The impact of size and shape of the excitation area on the condensate intensity profile will be discussed.