Free carrier induced changes in the absorption and refractive index for intersubband optical transitions in Al<i>x</i>Ga1−<i>x</i>As/GaAs/Al<i>x</i>Ga1−<i>x</i>As quantum wells

Abstract

The changes in the real index of refraction and the optical absorption for conduction intersubband transitions in AlxGa1−xAs/GaAs/AlxGa1−xAs quantum wells are examined as a function of the carrier density. Various values for the input optical field and quantum well width are considered in the calculations. The linear contribution due to χ(1) as well as the nonlinear contribution from χ(3) is included. The relationship of the results to device applications such as waveguides and optical modulators is discussed.