Solitons, half-solitons and vortex lattices in a polariton fluid
This work is devoted to the study of polariton quantum fluids in semiconductor microcavities and in particular to the generation of solitons, half-solitons and vortex lattices in these systems. We develop an experimental setup allowing for the generation and the observation of dark solitons in a polariton fluid. We observe characteristic density and phase profiles, and study the stability of solitons. We show experimentally that using a linearly polarised pump, half-solitons are formed due to the effective magnetic field arising in presence of the two spin populations. After the characterization of the half-solitons in density and phase, we perform a complete tomography of the emission to extract the information stored in the pseudospin. These studies allow us to highlight a formal analogy between half-solitons and magnetic monopoles. Then we investigate vortex trapping techniques. We make use of metallic masks to create potential wells trapping hydrodynamically generated vortex in the wake of a defect. At low polariton density we used the masks to realise vortex and antivortex lattices with adjustable shape and size. The study of the polariton-polariton interaction at high density leads us to use an experimental setup with several pumps allowing for the observation of strong modifications and washing-out of the lattices.