Linear electroabsorption in semi-insulating GaAs/AlGaAs asymmetric double quantum wells

Electroabsorption has been investigated in semi-insulating asymmetric GaAs/ AlGaAs double quantum wells presenting high linear Stark responses, adequat e for photorefractive applications. We have used the envelope function appr oximation to calculate the linear Stark shifts of the energy levels and sel ect a suitable structure for the experimental study. The experimental data indicate that the response to the applied field critically depends on a com plicated interplay of effects that compete or cooperate to suppress or enha nce the electroabsorption. For positive field polarity, the competing contr ibutions of the overlapping e1-hh1 and e1-hh2 transitions partially cancel the electroabsorption despite large linear Stark shifts. On the other hand, small negative fields induce large electroabsorption because the Stark shi fts of the two transitions have opposite signs. (C) 1999 American Institute of Physics. [S0021-8979(99)02119-2].