Dr Samuel ShuttsABDULMAJEED ABALRUHMAN ADBULAZIZ ALSHEMIMRI2022-05-292022-05-29https://drepo.sdl.edu.sa/handle/20.500.14154/46174Miniaturized atomic clocks (MACs) are based on coherent population trapping (CPT), which uses fundamental physics package components including a single/fundamental mode laser diode (VCSEL typically). These include beam conditioning optics and a quarter-wave plate/ND filter, a cell consisting of alkali atoms vapor, and a photo-detector. Several measures are available that can be used for better designing of VCSELs to improve the performance of miniaturized atomic clocks (MACs). This research project sought to identify some of these measures. The main aim of the current study is based on the measurement, which can help in improving the design of VCSELs and optimize the performance of miniaturized atomic clocks (MACs). Modeling of the passive cavity’s optical properties included the reflectivity of the cavity resonance and the upper and lower DBR mirrors. Further, the effect of different designs on the cold-cavity linewidth was also investigated. The wavelength was measured to check its suitability for a cesium atomic clock with a wavelength of 894.6 nm. Moreover, the specific temperature at which this wavelength was measured determined by considering the change of wavelength with respect to temperature. FIMMWAVE was adopted in this study. FIMMWAVE has the capability to assume almost any geometry in addition to a mode finder that is generic, robust, and fully vectored. This is also usable with 3D waveguide structures. This study revealed that for the temperatures (25oC and 25.6oC), spontaneous emissions significantly contribute to the output power. The main reason behind this could be the relatively low temperature, which allows more spontaneous emission to out of the top mirror. The results of the current study showed that an increase in temperature results in the decrease in slope efficiency indicating an inverse relationship between the slope efficiency and temperature. The results also showed that the VCSEL is biased with threshold currents and temperatures. The influence of the doping concentration on the VCSEL output performance has also been investigated. The lower threshold current and the maximum output power have been observed when the spacer layers and the distributed Bragg reflector DBR are doped with higher levels of the doping concentration. The results also indicated that doping can profoundly influence VCSEL’s slope efficiency.en