In this study, refractive index changes associated with in- tersubband transitions in a spherical quantum dot, GaAs/AlxGa1ixAs, have been theoretically calculated in the presence of impurity. In this regard, the efiect of dot radius, stoichiometric ratio, impurity and in- cident optical intensity on the refractive index changes have been in- vestigated for the transitions between higher energy states, i.e., 1s-1p, 1p-1d and 1d-1f. The results show that these parameters have a great in∞uence on the refractive index changes.