LOCAL-FIELD EFFECT ON THE LINEAR OPTICAL INTERSUBBAND ABSORPTION IN MULTIPLE-QUANTUM WELLS

Using a microscopic local-field formulation, the linear optical absorp tion of a multiple-quantum-well (MQW) structure associated with inters ubband transitions is investigated. Taking as a starting point a funda mental self-consistent integral equation for the local field, the p-po larized electric-field distribution inside each quantum well in the MQ W structure is studied. It is demonstrated that the local field is ess entially determined from a set of linear algebraic equations. Within t he infinite-barrier approximation with an effective well width, numeri cal calculations of the optical absorption spectra are presented for a GaAs/AlxGa1-xAs multiple quantum well for different parameters such a s the two-dimensional (sheet) electron concentration, the angle of inc idence, and the number of wells. The numerical results show that the l ocal-field effect leads to a notable blueshift of the peak-position en ergy in the absorption spectra as the sheet density of the electrons i s increased, and that for larger angles of incidence the electromagnet ic interaction among quantum wells gives rise to a significant broaden ing of the absorption peak when the number of wells is sufficiently la rge.