Biexcitonic absorption in a disk-shaped GaN quantum dot

Abstract

The present work investigates the nonlinear optical properties of a GaN quantum dot in the disk limit via the exciton and biexciton states using the compact density matrix formalism. Based on this model, we calculate the ground state energy of the exciton and biexciton states by the variation method, within envelope function and effective mass approximations. Linear and nonlinear optical absorption (α (1), α (3)) and oscillator strengths attributed to the optical transitions are obtained. The details of the behaviour of α (1) and α (3) around the resonance frequencies and for different quantum dot geometries are presented. It is found that the size of quantum dot and the optical intensity have a remarkable effect on the optical absorption, and the biexcitonic two-photon absorption coefficient(K 2) has also been calculated in this system. The results show that this parameter is strongly affected by the size of the quantum dot.