Abstract
In this work, we discuss the stability of roll solutions for exciton-polariton condensates in wide aperture semiconductor microcavities operated in the strong coupling regime when pumped with a coherent beam. From which, we progress to study the behavior of vortices and solitons on a Gaussian background. Individually, all vortices with winding number |m| > 1 are found to be unstable and decay into the appropriate number of stable m = 1 vortices.Using these stable vortices, we propose new classes of vortex lattices that are supported through the parametric conversion of polaritons. Both the honeycomb and square lattices are determined to be robust in practically relevant settings, for an appropriate angle of the probe beam, seeding in the signal region of momentum space. For other angles, we discuss the two possible melting scenarios.
Through the introduction of polarization into the system, it is seen that multiple bistability regions exist. By extending the study of honeycomb lattices to include these effects, we show that stable lattices can only exist for a circular or linearly polarized pump and probe. In the linearly polarized system, vector solitons are observed, where the existence of stable vector solitons, in one dimension and two dimensions, is demonstrated along all three branches. Under an elliptically polarized pump, it is seen that only the first of the two bistability regimes hosts a family of stable vector dark bright solitons, whilst the second higher energy branch is generally unstable.
In two dimensions, we observe that perpendicular to the pump axis, all forms of vector solitons will either contract or expand dependent upon the pump intensity, mirroring the dynamics of scalar solitons. Finally, we discuss the potential for coherent control of these solitons is then demonstrated the switching of the polarization state.
| Date of Award | 24 Feb 2012 |
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| Original language | English |
| Awarding Institution |
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| Supervisor | Dmitry Skriabin (Supervisor) |
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