This work presents a comprehensive numerical simulation and analysis of vertical cavity surface emitting lasers (VCSELs) at room temperature. The design focuses on optimization \(\:{\text{I}\text{n}}_{0.05}{\text{G}\text{a}}_{0.95}\text{A}\text{s}/{\:\text{A}\text{l}}_{0.3}{\text{G}\text{a}}_{0.7}\text{A}\text{s}\) multi quantum-wells (MQWs) to achieve high gain, enclosed between 20- pairs top and 35-pair bottom of \(\:{\text{A}\text{l}}_{0.9}{\text{G}\text{a}}_{0.1}\text{A}\text{s}/{\text{A}\text{l}}_{0.15}{\text{G}\text{a}}_{0.85}\text{A}\text{s}\) distributed Bragg reflectors (DBRs) with reflectivity exceeding 99.9%. The optimized structure yields a high gain at around 40 dB at the center emission wavelength of 850 nm. Frequency response analysis further predicts a -3dB modulation band width of up to 36 GHz, demonstrating strong potential for high-speed optical interconnects. The results emphasize the influence of aluminum ( \(\:Al\) ) concentration in \(\:{Al}_{x}{Ga}_{1-x}As\) DBRs for enhancing optical confinment, as well as the contribution of \(\:InGaAs\) MQWs in improving carrier concentartion and material gain. Together, these strutural optimizations significantly enhance VCSEL performance and modulation bandwidth, providing valuable insights for the next generation high speed optoelectornic devices.
