1. Department of Physics, National Sun Yat-sen University, Kaohsiung, Taiwan
2. Department of Photonics, National Sun Yat-sen University, Kaohsiung, Taiwan
3. Department of Electrical Engineering, National Sun Yat-sen University, Kaohsiung, Taiwan
4. Department of Materials and Optoelectronic Science, National Sun Yat-sen University, Kaohsiung, Taiwan
5. Department of Physics, Republic of China Military Academy, Kaohsiung, Taiwan