1. Department of Physics, National Taiwan Normal University, Taipei 11677, Taiwan
2. Department of Mathematics and Physics, University of Santo Tomas, Manila 1008, Philippines
3. Department of Electrophysics, National Chiao Tung University, Hsinchu 30010, Taiwan
4. School of Materials Science and Engineering, University of Science and Technology Beijing, Beijing 100083, People’s Republic of China
5. Graduate Institute of Electro-Optical Engineering, National Taiwan Normal University, Taipei 11677, Taiwan