Linear and nonlinear optical processes in GaAs semiconductor microcavities

In this thesis, polariton dynamics in GaAs semiconductor microcavities are investigated. Insertion of layers of active material within a Fabry-Perot resonator leads to strong coupling between excitons and photons, giving rise to new eigenmodes called excitonpolaritons. Bose-Einstein condensation, the ability for massive occupation of a quantum state is considered a fascinating property of polaritons, due to their bosonic character. A full study of polariton condensation in 2D and 0D microcavities is included in this thesis. Formation of a ground state condensation in a planar cavity is resolved by studying the spatial, angular, coherence, energy and transient dynamics of polariton photoluminescence, as well as the transition from the weak- to the strong-coupling regime in the time-domain. The role of longitudinal optical phonons in the relaxation dynamics is also investigated. Encouraging experimental results confirm the efficiency of this mechanism towards the formation of a ground state condensate. Polariton condensation in 0D GaAs quantum well microcavities is facilitated by etching the 2D semiconductor microcavity sample into pillars, removing the wavevector conservation. The spontaneous formation of a condensate in ground and non-ground states in 0D microcavities is investigated experimentally. A complete kinematic model that satisfactorily describes the spectral and temporal behaviour of polaritons in 0D structures completes this study. Finally, the observation of the all optical spin Hall effect, the separation of spin polarised carriers in real and momentum space, in a pure photonic cavity is included in this thesis. Experimental findings suggest that the excitonic contribution in similar observations in the strong coupling regime with polaritons acting as spin carriers, is not essential for the observation of the anisotropic polarisation flux.