The enhancement of electron barrier height by multi-quantum barrier structure is simulated using transfer matrix method. An effective barrier height as high as 5.5 times the classical potential barrier is designed by using five stacks of GaAs/AlAs superlattices. Based on the simulated results, we construct both 0.78 mu m and 1.3 mu m graded-index separate confinement heterostructure lasers with enhanced carrier and optical confinements using graded multi-stack multi-quantum barriers. The threshold current densities of the lasers are estimated to be lower than those of the conventional graded-index separate confinement heterostructure lasers. Higher characteristic temperatures are also expected for these lasers.