Dynamic of quantum Cascade Laser

This study aimed to provide advanced analysis of the emission characteristics of a quantum cascade laser (QCL) by developing a comprehensive mathematical model. The model focused on simulating the dynamics of carriers (electric charges) within the upper and lower subbands of the laser structure, along with tracking the evolution of photon numbers in the device cavity.The study was able to accurately quantify the laser output delay time and study its dependence on key operating parameters, most notably the injection current. The variation in the number of affected photons was also monitored and interpreted, and the sensitivity of this number to changes in the injection current was assessed. Critical relaxation lifetimes were measured and derived: This included calculating the carrier relaxation lifetime in both the upper and lower subbands, which sheds light on energy loss mechanisms and charge injection efficiency. Spontaneous emission characteristics were also evaluated: This included calculating the spontaneous emission lifetime and determining the spontaneous emission coefficient, as key indicators of photon loss outside the desired stimulated emission process.The results of this research represent a qualitative addition to our understanding of the temporal and dynamic mechanisms governing the operation of a quantum cascade laser. The mathematical model provides a powerful tool for predicting laser behavior and optimizing its design parameters, paving the way for achieving higher-efficiency devices and more stable performance in advanced practical applications.