Biexcitonic effect on the nonlinear optical properties of GaAs/Al_xGa_(1-x)As quantum wire near the band edge

摘要

Using the time dependent perturbation technique for a three-level system, we have investigated theoretically the role of biexcitons on the quasi-steady state nonlinear optical processes like nonlinear refraction and nonlinear absorption in GaAs/Al_xGa_(1-x)As semiconductor quantum wire (QWR). The semiconductor absorption spectrum is assumed to exhibit Wannier–Mott type of discrete excitonic structure near the band edge. We have incorporated the relaxation and dephasing mechanisms for both excitons and biexcitons phenomenologically. The real and imaginary parts of the third-order nonlinear optical susceptibility responsible for the occurrence of nonlinear refraction and absorption, respectively, have been derived from the expression for the induced polarization in the QWR. Numerical estimates made for GaAs/Al_xGa_(1-x)As QWR manifest distinctly the influence of biexcitons on both nonlinear refraction and absorption.