In this study we investigate strain effect in barriers of 1.3 μm AlGaInAs-InP uncooled multiple quantum well lasers. Single effective mass and Kohn–Luttinger Hamiltonian equations have been solved to obtain quantum states and envelope wave functions in the structure. In the case of unstrained barriers, our simulations results have good agreement with a real device fabricated and presented in one of the references. Our main work is proposal of 0.2% compressive strain in the structure Barriers that causes significant reduction in Leakage current density and Auger current density characteristics in 85 °C. 20% improvement in mode gain-current density characteristic is also obtained in 85°C.