We have studied the optical properties of lattice‐matched GaAs/AlxGa1−xAs and InyGa1−yAs/GaAs strained‐layer superlattices grown on Si substrates using the photoreflectance technique. These preliminary results show that good quality III‐V epilayers can be grown on Si. The experimental data were compared with calculations based on the envelope‐function approximation and fitted to the third‐derivative functional form of reflectance modulation theory.