SPATIAL SOLITONS IN SEMICONDUCTOR MICROCAVITIES

We consider a semiconductor microcavity driven by a coherent and stati onary holding beam, in two distinct configurations. In the first, no c arriers are injected in the. multiple-quantum-well structure and the o ptical nonlinearity is governed by an excitonic resonance. The second corresponds to that of a vertical-cavity surface-emitting laser kept s lightly below threshold. We describe both configurations using a unifi ed model that includes both field diffraction and carrier diffusion. W e calculate numerically both the time evolution and the stationary pro file of the solitonic solutions, using a generalization of the radial integration technique introduced by Firth and Scroggie [Phys. Rev. Let t. 76, 1623 (1996)]. We analyze the instability that forms spatial pat terns and especially cavity spatial solitons. We predict the existence of these solitons in various parametric domains for both configuratio ns. 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 ca rrier diffusion, and even to some amount of self-defocusing. This pict ure points to the possibility of realizing arrays of solitonic pixels using semiconductor microresonators.