GaAs/AlAs quantum wells for electroabsorption modulators

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Abstract
We demonstrate both theoretically and experimentally that the quantum-confined Stark effect leads to larger absorption changes in GaAs/AlAs quantum wells compared to the more conventional GaAs/AlGaAs system due to the higher Γ confinement. The lower indirect valleys in AlAs do not degrade the performance and the exciton resonance is maintained at higher-energy shifts. The improvement in exciton oscillator strength is nearly 50% with a 70-meV shift. The greater exciton strength at high fields has important applications for optical modulators and switches that operate at the long-wavelength side of the zero-bias exciton.