**8. Conclusions**

The progress towards SOAs, and then QD-SOAs, is reviewed. The importance of Sb-based structures is illuminated. To see the effect of QD-SOA layers, a REs for QD, WL and SCH layers are solved numerically. This make us specify gain-input power relation for Sb-based QD-SOAs and then examine layers dynamics. Both QD and SCH layers are shown to have an importance in the static characteristics due to their considerable effect in structure confinement. WL is shown to affect carrier dynamics especially in the ES and GS. Global quasi-Fermi energy (which included SCH, WL, QD ES and QD GS) is shown to be important in the explanation of results. At all cases, the inclusion of the SCH in the REs is shown to be essential.
