[1] Natl Taiwan Univ, Dept Phys, Taipei 10617, Taiwan
[2] Natl Taiwan Univ, Div Phys, Natl Ctr Theoret Sci Taipei, Taipei 10617, Taiwan
[3] Fudan Univ, Minist Educ, State Key Lab Surface Phys, Shanghai 200433, Peoples R China
[4] Fudan Univ, Minist Educ, Key Lab Micro & Nano Photon Struct, Shanghai 200433, Peoples R China
[5] Natl Chengchi Univ, Grad Inst Appl Phys, Taipei 11605, Taiwan
[6] Univ Southampton, Optoelect Res Ctr, Southampton SO17 1BJ, Hants, England
[7] Univ Southampton, Ctr Photon Metamat, Southampton SO17 1BJ, Hants, England
[8] Natl Appl Res Lab, Instrument Technol Res Ctr, Hsinchu 300, Taiwan
[9] Acad Sinica, Res Ctr Appl Sci, Taipei 11529, Taiwan