Third-order non-linear susceptibility in a three-level QD system

Third-order non-linear susceptibility is derived for a three-level quantum dot system. Then the total absorption (linear and non-linear) for InGaAsP three-level quantum dot systems is calculated at various parameters (wetting layer composition, pump power, quantum size effect and dephasing linewidth). The spectral hole appears at low power with increasing Ga mole-fraction in the wetting layer.