| Résumé | We demonstrate efficient wave-guide quantum-well electroabsorption modulators that also show good performance as lasers, in GaAs–AlxGa1−xAs. Two structures, having one and three quantum wells in the wave-guide core, are considered. We show that, although the background-doping impurity level in the intrinsic region is high enough to quench the exciton absorption peaks, efficient electroabsorption can still be achieved. We obtain maximum changes in absorption of between 140 and 250 cm−1 for both samples, depending on the polarization. For the three-well sample we observe a dramatic reappearance of exciton-absorption peaks under an applied field that enhances the contrast ratio. For the single-well sample, however, no excitonic features are observed for any applied field. Finally, the wave-length dependent chirp parameters is calculated at various bias voltages via the Kramers–Kronig relations. Both samples show chirp parameters of less than unity throughout most of the wavelength region of interest. |
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