This thesis focuses on numerical study of a longitudinally pumped continuous wave (CW) Nd:YVO4 laser by high power VCSEL modules. Two VCSEL pump modules (6 W and 15 W) were compared. The performance of Nd:YVO4 crystal was found to be better than that of Nd:YAG crystal. Our numerical results indicate that VCSELs can serve as efficient pump sources for the end-pumped CW Nd:YVO4 lasers. Internal cavity loss (Li) is an important parameter in the modeling and optimization of laser’s performance. A new method for the calculation of the Li for longitudinally pumped lasers was introduced. This method can be conducted without making any changes to the CW laser cavity and it also can be performed faster compared to the widely used method called Findlay-Clay analysis. A successful experiment was conducted to find the Li based on both methods with good agreement between the two.