1. Department of Physics, National Sun Yat-sen University, Kaohsiung, Taiwan
2. Department of Physics and the Center of Crystal Research, National Sun Yat-sen University, Kaohsiung, Taiwan
3. Department of Electrical Engineering, National Sun Yat-sen University, Kaohsiung, Taiwan
4. Department of Photonics, National Sun Yat-sen University, Kaohsiung, Taiwan
5. Department of Materials and Optoelectronic Science, Institute of Electronics, National Yang Ming Chiao Tung University, Hsinchu, Taiwan
6. Department of Physics, Republic of China Military Academy, Kaohsiung, Taiwan
7. Department of Electronics Engineering, Institute of Electronics, National Chiao-Tung University, Hsinchu, Taiwan