We demonstrate what we believe to be the first experimental observation of self-trapping and self-deflection of a planar optical beam by the photorefractive effect in a semiconductor. The semiconductor material is indium phosphide doped with iron. We show that the observed focusing and defocusing effects follow the component of the two-wave-mixing space charge field that is in phase with the intensity pattern, whereas the spatial beam deflection effects follow the 90 degrees -shifted component.

We demonstrated an experimental observation of self-trapping and self-deflection of a two-dimensional optical beam by the photorefractive effect at telecommunication wavelengths under an applied dc field. Self-trapping is effective for an intensity range related to the intensity-temperature resonance known for two-wave mixing in InP:Fe. The photorefractive index change giving rise to the trapping is measured at 10−4, while the photorefractive space-charge field is measured at about 50 kV/cm, ten times higher than the applied field. We show experimentally that this index change creates a waveguide that can be used to guide a second beam at 1.55 μm.

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A coherent all-optical nonlinear polarization switch based on exciton–exciton correlations is demonstrated in a multiple-quantum-well semiconductor structure. A contrast ratio of 8:1 and a relaxation time of less than a picosecond are reported at 80 K using only ten wells. The results are compared to a simple phenomenological model to demonstrate that many-body effects are solely responsible for the switching action and that the turn-on and turn-off times are determined by the dephasing time.