Spatial solitons in semiconductor microcavities

We consider a semiconductor microcavity driven by a coherent and stationary holding beam, in two distinct configurations. In the first, no carriers are injected in the multiple-quantum-well structure and the optical nonlinearity is governed by an excitonic resonance. The second corresponds to that of a vertical-cavity surface-emitting laser kept slightly below threshold. We describe both configurations using a unified model that includes both field diffraction and carrier diffusion. We calculate numerically both the time evolution and the stationary profile of the solitonic solutions, using a generalization of the radial integration technique introduced by Firth and Scroggie [Phys. Rev. Lett. 76, 1623 (1996)]. We analyze the instability that forms spatial patterns and especially cavity spatial solitons. We predict the existence of these solitons in various parametric domains for both configurations. We demonstrate that these results are independent of the periodic boundary conditions used in the simulations. We show that, introducing a simple phase modulation in the holding beam, one can eliminate the motions of solitons that arise from noise and from amplitude gradients. The solitons are robust with respect to parametric variations, to carrier diffusion, and even to some amount of self-defocusing. This picture points to the possibility of realizing arrays of solitonic pixels using semiconductor microresonators.