Effect of the Stark confinement on the excitonic optical spectrumof an array of coupled quantum dots

We investigate theoretically the influence of a uniform electric field on the optical properties of a linear array of coupled quantum dots. We study the excitonic spectrum of this system by solving the electron-hole effective-mass Hamiltonian. The potential along the array is modeled by a periodic square-well potential and we assume parabolic lateral confining potentials for electrons and holes. We calculate the excitonic absorption coefficient as a function of the quantum dot size and the applied electric field. We discuss the different confinement regimes. The results illustrate the competing effects of the lateral confinement, the electric-field confinement, and the Coulomb interaction. We show that in the weak-lateral confinement regime the natural coordinates are the relative and the center-of-mass coordinates which are weakly coupled by the lateral potential. In the strong-lateral confinement regime the electrons and holes are weakly correlated and the spectrum can be explained in a single-particle picture.