We have demonstrated a novel approach to achieve a stable multi-wavelength laser system (MWLS) which is making use of a quantum dot semiconductor optical amplifier (QD SOA) as a highly birefringence material and an optical polarizer at the same time. Both the channel frequency spacing and the central lasing wavelength of the QD MWLS can be accurately set by using the desired-designed QD SOA with the certain operation conditions and by setting the polarization controller properly. The detailed working principles and the experimental results have been reported in this paper. The proposed QD MWLS technology can be used for characterizing the intrinsic properties of the QD semiconductor waveguide materials that could also be used for spectral narrowing of a laser system. We have experimentally confirmed that the QD SOA is highly inhomogeneous gain material as compared with QW SOA.