1. Research Center for Applied Sciences, Academia Sinica, 128 Sec. 2, Academia Road, Nankang, Taipei 115, Taiwan
2. Department of Materials Science and Engineering, National Chiao Tung University, Hsinchu 300, Taiwan
3. Department of Photonics & Institute of Electro-Optical Engineering, National Chiao Tung University, Hsinchu 300, Taiwan