1. Green Energy and Environment Research Laboratories, Industrial Technology Research Institute (ITRI), 195, Section 4, Chung Hsing Road, Chutung 31040, Taiwan
2. Department of Photonics and Institute of Electro-Optical Engineering, National Chiao Tung University, Hsinchu 30010, Taiwan
3. Institute of Photonic System, National Chiao Tung University, Tainan 711, Taiwan
4. Department of Materials Science and Engineering, National Tsing Hua University, Hsinchu 30013, Taiwan