In this paper, a numerical study of barrier characterization effects on the high-temperature internal performance of an InGaAsP multi-quantum well laser is presented. The softwareused for this purpose self-consistently combines the three-dimensional simulation of carrier transports, self-heating, and optical waveguiding. The laser model calculates all relevant physical mechanisms, including their dependence on temperature and local carrier density. The results have shown that the proposed laser, which operates at 1325 nm, suffers from electron leakage. The electron leakage current decreases by reducing the barrier thickness. Although tensile strain barriers lead to improved laser optical behavior, it increases leakage current because of electron non-uniformity.