Rouzbeh Ghanbarnezhad Moghanloo, for his guidance, assistance, and support during my graduate studies. It is his generous help and invaluable advice that enable me to accomplish this thesis. The door to his office was always open whenever I ran into a trouble spot or had a question about my research or writing. I appreciate his support on providing COMSOL license, which has made a great contribution to this work. I would also like to acknowledge Dr. Siddharth Misra and Dr. Bor-Jier (Ben) Shiau for serving as my committee members and reviewing my thesis. I learned lots of valuable knowledge that may help me in the future work through their courses and advices. Furthermore, I would like to appreciate Dr. Davud Davudov and Dr. Da Zheng for their assistances on my research. Their intelligent knowledge always give me inspirations on my work. I would also like to thank my fellow and friend Xu Yan who gave me great helps during my graduate studies. Moreover, I would like to say thank you to my friends Hao Zhang, Zhaoyi Zhuo, Yue Fang, and Xiameng Peng for their accompanies during my undergraduate life at OU. Finally, I would like to express my deepest appreciation to my parents whose love are with me in whatever I pursue. Their unfailing support and continuous encouragement throughout my study years provide me solid foundation to accomplish this thesis. They are always my life-coaches. vi