Modulational instability and solitons in excitonic semiconductor waveguides

Oleksii A. Smyrnov, Fabio Biancalana, Stefan Malzer

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Abstract

Nonlinear light propagation in a single-mode micron-size waveguide made of semiconducting excitonic material has been theoretically studied in terms of exciton polaritons by using an analysis based on macroscopic fields. When a light pulse is spectrally centered in the vicinity of the ground-state Wannier exciton resonance, it interacts with the medium nonlinearly. This optical cubic nonlinearity is caused by the repulsive exciton-exciton interactions in the semiconductor, and at resonance it is orders of magnitude larger than the Kerr nonlinearity (e.g., in silica). We demonstrate that a very strong and unconventional modulational instability takes place, which has not been previously reported. After reducing the problem to a single nonlinear Schrodinger-like equation, we also explore the formation of solitary waves both inside and outside the polaritonic gap and find evidence of spectral broadening. A realistic physical model of the excitonic waveguide structure is proposed.

Original languageEnglish
Article number205207
Number of pages7
JournalPhysical Review B: Condensed Matter and Materials Physics
Volume83
Issue number20
DOIs
Publication statusPublished - 15 May 2011

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