Photorefractive dark solitary wave formation in semiconductor GaAs/AlGaAs structures

Dark photorefractive solitons generated in semiconductor materials can be used to induce optical waveguides, which could be a step towards the construction of reconfigurable optical circuits. Compared to bright solitons, dark solitons have the advantage of lower refractive index changes needed for their generation. The authors present results of research on the generation of dark spatial solitons in photorefractive semiconductor materials characterised by bipolar charge carrier transport and nonlinear electron transport. The study has been carried out for an external electric field of strength values lower than those applied in research on bright solitons. Three qualitatively different photorefractive responses have been distinguished in the outcome of the analysis, namely: a standard response, a nonlocal, strongly asymmetric response, and a response consisting in the generation and oscillation of charge carrier domains. The complex process of soliton formation has been discussed and the feasibility of extending the research to include the application-relevant, telecommunication wavelength band has been highlighted.