Referred to the laser structure and its experimental results obtained by Selmic et al. and Liu et al., optimized active structure for the 1.55-µm quantum well lasers based on AlGaInAs material system is investigated. A structure with 1.2% compressive-strained wells and a p-type AlInAs electron stopper layer of 20 nm thickness and 5×10 23 m −3 doping concentration is suggested. Using this structure the threshold current is reduced to 17.8 mA, and the electron overflow percentage is decreased to 1.74% at 330 K. Furthermore, the characteristic temperatures of threshold currents are enhanced to 55.6 K, 67.0 K, and 43.3 K in operating temperature ranges of 300 K~350 K, 300 K~330 K, and 330 K~350 K, respectively.