We have produced AlxGa1−xAs‐AlAs quantum wellp‐i‐ndiode electroabsorption modulators withxas high as 0.56. Even though the material is indirect in momentum space, strong excitonic absorption exists at the direct band gap which can be modulated with an applied field. Forx=0.33, 0.43 and 0.56, we measure relative transmission changes (&Dgr;T/T0, in a surface‐normal configuration) of 62%, 51%, and 23%, respectively, at wavelengths of 677, 622, and 575 nm for 15 V bias with the intrinsic layer being 0.6 &mgr;m thick.