1. Department of Physics, National Sun Yat-sen University, Kaohsiung, Taiwan
2. Department of Materials and Optoelectronic Science, National Sun Yat-sen University, Kaohsiung, Taiwan
3. Department of Photonics, National Sun Yat-sen University, Kaohsiung, Taiwan
4. Department of Physics, Military Academy, Kaohsiung, Taiwan
5. Department of Electrical Engineering, National Tsing-Hua University, Hsinchu, Taiwan
6. Institute of Electronics, National Yang Ming Chiao Tung University, Hsinchu, Taiwan