Effect of zinc impurity-induced disordering on the refractive index of GaAs/AlGaAs multiquantum wells

We report on the variation of the refractive index of a GaAs/AlGaAs multiquantum well of well width 6.5 nm and barrier width 19 nm, introduced by zinc impurity-induced disordering. We employ a structure consisting of several uncoupled, multiquantum well ridge waveguides with tapered disordering across the transverse direction. The refractive index changes have been deduced as a function of the interdiffusion length of Ga/Al by the use of an interference technique. We measured a maximum index change of 0.083 and 0.062 for significant disordering (L_d=6.6 nm) at 35 and 100 meV below the band edge of the undisordered multiquantum well, respectively.