We demonstrated a quantum‐confined Stark effect electroabsorption modulator consisting of quantum wells of AlGaAs and GaAs on an epitaxial multilayer dielectric mirror, all grown by molecular beam epitaxy. The resulting reflection modulator avoids problems of substrate absorption, and has relatively high contrast ratio (up to ∼8:1 with peak reflectivity of 25% at 853 nm) because the light passes twice through the quantum wells. Reflection modulators are of interest for bidirectional communication systems, in parallel arrays of optical switching and processing devices and for optical interconnects. For the latter there exists the possibility of this device grown on the same substrate alongside a GaAs integrated circuit or even on Si substrates.