We have studied the electroabsorptive properties of symmetrically strained (GaIn)As/Ga(PAs) superlattices consisting of 100 periods. Photocurrent measurements at 4 K reveal a pronounced pseudo‐blue shift and a Wannier–Stark splitting of the heavy‐hole exciton transition. A self‐electro‐optic effect device has been realized which makes use of the pseudo‐blue shift due to the Wannier–Stark localization and of the transparency of the GaAs substrate. The self‐electro‐optic effect devices show on–off contrast ratios of 2.1 at 77 K and of 1.3 at room temperature. ©1996 American Institute of Physics.