1. Department of Applied Chemistry, Providence University, Taichung 43301, Taiwan, Republic of China
2. Department of Electrical Engineering, Yuan Ze University, Chungli 32003, Taiwan, Republic of China
3. Department of Photonics, National Chiao Tung University, Hsinchu 30010, Taiwan, Republic of China
4. Department of Photonics, National Sun Yat-sen University, Kaohsiung 80424, Taiwan, Republic of China