1. Department
of Physics, National Taiwan University, Taipei 10617, Taiwan
2. Research
Center for Applied Sciences, Academia Sinica, Taipei 11529, Taiwan
3. Department
of Electrical Engineering, National United University, Miaoli 36063, Taiwan
4. Department
of Photonics, National Cheng Kung University, Tainan 70101, Taiwan
5. College of
Engineering, Chang Gung University, Taoyuan 33302, Taiwan