1. Institute of Physics, National Chiao Tung University, No. 1001, Ta Hsueh Road, 300 Hsinchu, Taiwan
2. Department of Photonics, College of Electrical and Computer Engineering, National Chiao Tung University, No. 1001, Ta Hsueh Road, 300 Hsinchu, Taiwan
3. Institute of Electronics Engineering, National Tsing Hua University, No. 101, Section 2, Guangfu Road, 300 Hsinchu, Taiwan
4. Department of Chemistry, National Taiwan Normal University, 162, Heping East Road, Section 1, 106 Taipei, Taiwan