Photoluminescence measurements have been made on GaAs samples stressed with piezoelectric bimorphs. We show that measurable shifts in the energy gap can be obtained by mechanically stressing the semiconductor with a piezoelectric transducer. This principle can be applied to fabricate a class of wavelength‐tunable electro‐optic devices, such as tunable semiconductor lasers, light‐emitting diodes, and photodetectors.