This work is devoted to the study of the properties of polaritons, half-matter/half-light particles, in a semiconductor microcavity. Their bosonic behaviour enables to reach macroscopic coherence regimes such as Bose-Einstein condensation and super uflidity which we have experimentally demonstrated. We also developed a way to optically engineer the polariton landscape by creating arti cial defects on the sample, which will help finding some fancy behaviours such as turbulence. Thanks to the strong spin-dependant interactions between polaritons and the very high propagation speeds due to their photonic component, we could build an all-optical, ultra-fast spin switch device operating at low injected power. We managed to control the spatial distribution in spin of the polaritonic beam and con fine a pure spin state within a micrometer-sized region. The bistability of the system led us to reconsider the sign of the interaction constant between cross-polarized polaritons. Finally, we carried on investigating the possibility of generating twin photons in the parametric oscillation regime by four-wave mixing, with correlations measures and transverse-mode noise distribution analysis, in di fferent planar cavity types and in micropillars (0D).
