Electroabsorption in ultranarrow-barrier GaAs/AlGaAs multiple quantum well modulators

Abstract
We measure electroabsorption in GaAs/AlGaAs multiple quantum well modulators with ultranarrow barriers so as to maximize the overall absorption coefficient by removing optically inert barrier material. Reduction 0.3Ga0.7As barriers results in resonant well coupling degrading performance. For AlAs barriers, resonant coupling is eliminated and we observe sharp excitons and the quantum confined Stark effect for barriers as narrow as 10 Å. However, optimum normally‐on operation is obtained for 20–30 Å AlAs barriers, approximately 20% better than 38 Å Al0.3Ga0.7As barriers.