1. Department of Physics, National Taiwan University, Taipei 10617, Taiwan
2. National Center for Theoretical
Sciences at Taipei, Physics Division, National Taiwan University, Taipei 10617, Taiwan
3. Graduate Institute of Applied
Physics, National Taiwan University, Taipei
10617, Taiwan
4. Institute
of Opto-electronic
Engineering, National Dong Hwa University, Hualien 97401, Taiwan
5. State Key Laboratory of Surface
Physics and Key Laboratory of Micro and Nano Photonic Structures (Ministry
of Education) and Physics Department, Fudan University, Shanghai 200433, China
6. Graduate
Institute of Applied Physics, National Chengchi University, Taipei 11605, Taiwan
7. Research Center for Applied
Sciences, Academia Sinica, Taipei 115,
Taiwan