Abstract
The refractive index changes near the excitonic absorption edge in a GaAs‐AlxGa1−xAs quantum well structure due to an external electric field have been calculated. Calculated maximum variation in the refractive index is approximately −0.07 for an electric field of 80 kV/cm for both a 60‐Å‐thick and a 100‐Å‐thick GaAs‐Al0.4Ga0.6As quantum wells. Also calculated results indicate that the forbidden excitonic transition, which comes to be allowed in the presence of an external electric field, has much greater effect for relatively thick quantum wells.