Carrier-induced refractive index in quantum dot structures due to transitions from discrete quantum dot levels to continuum states

Abstract

The carrier-induced refractive index in quantum dot (QD) structures due to optical transitions from QD levels to continuum states is considered. It is shown that, for large photon energies, the refractive index change is given asymptotically by the Drude formula. Calculations of the linewidth enhancement factor, α, show that α∼1 due to this contribution to the total refractive index. Furthermore, for highly localized QD states, the absorption coefficient at the photon energies ∼0.8–1.0 eV due to these transitions can be on the order of 103 m−1.