Nonlinear absorption in semiconductor quantum dots

The density matrix approach has been employed to understand the mechanism o f nonlinear absorption / gain in a single semiconductor quantum dot as well as in an inhomogeneous distribution of quantum dots. The analytical result s show an enhancement of excitonic gain in the presence of biexcitons. The same has been confirmed by the numerical analysis carried out for a realist ic system of semiconductor quantum dots of CdS embedded in a glass matrix. The numerical study exhibits a red shift of maximum gain at large distribut ion widths. (C) 2001 Elsevier Science Ltd. All rights reserved.