Theoretical study of the optical absorption and refraction index change in a cylindrical quantum dot

Analytical expressions of the optical absorption coefficient and the change in refractive index associated with intraband relaxation in a cylindrical quantum dot are obtained by using the density matrix formalism. Energy levels in conduction band were calculated with finite confining potential in the framework of the effective-mass envelope-function theory. Numerical calculations on a typical GaAs/AlβGa1−βAsAlβGa1−βAs QD are performed. It is found that the absorption and refraction index change sensitively depend not only on the incident optical wave but also on the dot size and the Al mole fraction β   in the AlβGa1−βAsAlβGa1−βAs material.