Optimized Asymmetric Double Quantum Well for High Electric-Field-Sensitivity Electroabsorption: Excitonic Mixing Effects

Abstract

Asymmetric double quantum wells (ADQWs) are optimized to exhibit maximum optical modulation sensitivity by varying the barrier width, barrier position, and well width. Anticrossing of the two lowest excitons in ADQWs significantly enhances the modulation sensitivity. Consideration of exciton mixing is crucial to obtain accurate estimates of the effects. For a given linewidth of the excitonic peaks, we find optimum structural parameters that exhibit maximum modulation sensitivity. Values dalpha / dE ~ 6.51 x 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">4</sup> kV <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-1</sup> of of at 4.2 K and ~1.25 x 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sup> kV <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-1</sup> of at 298 K are predicted in GaAs-based ADQWs. The result provides new design guidelines in fabricating high-sensitivity QW electroabsorption modulators.