[1] Acad Sinica, Inst Phys, Taipei 11529, Taiwan
[2] Natl Chengchi Univ, Grad Inst Appl Phys, Taipei 11605, Taiwan
[3] Ming Chuan Univ, Dept Informat & Telecommun Engn, Taipei 111, Taiwan
[4] Natl Cheng Kung Univ, Dept Phys, Tainan 70101, Taiwan
[5] Natl Cheng Kung Univ, Adv Optoelect Technol Ctr, Tainan 70101, Taiwan
[6] Fu Jen Catholic Univ, Dept Phys, Taipei 242, Taiwan