This article indicates the effects of physical dimensions variations on optical properties of GaAs/AlGaAs multiple quantum well (MQW) slow light devices based on coherent population oscillations (CPO) method. These physical parameters include, quantum well size and number. Bloch equations have been used to analyze and simulate the device with different parameters. This paper offers several methods for tuning the central frequency and slow down factor (SDF) of the slow light device. Based on these proposed approaches, we could improve optical properties of MQW slow light devices. According to simulation results, the maximum value of SDF can be achieved in a range of 3×10⁵ with variations of physical parameters.