1. Department of Physics, National Taiwan University, Taipei 10617, Taiwan
2. School of Physics and Optoelectronic Engineering, Foshan University, Foshan, Guangdong 528000, China
3. Department of Applied Physics, National Pingtung University, Pingtung 90003, Taiwan
4. Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei 10671, Taiwan
5. Research Center for Applied Science, Academia Sinica, Taipei 11529, Taiwan