[1] Natl Sun Yat Sen Univ, Dept Phys, Kaohsiung 804, Taiwan
[2] Natl Sun Yat Sen Univ, Dept Mat & Optoelect Sci, Kaohsiung 804, Taiwan
[3] Natl Cheng Kung Univ, Adv Optoelect Technol Ctr, Tainan 700, Taiwan
[4] China Natl Petr Cooperat, BGP, Ctr Informat Technol, Beijing 100007, Peoples R China
[5] Tung Fang Design Inst, Dept Elect Engn & Comp Sci, Kaohsiung 829, Taiwan
[6] Natl Kaohsiung Normal Univ, Dept Chem, Kaohsiung 802, Taiwan
[7] Xiamen Univ, Dept Phys, Xiamen 361005, Peoples R China
[8] Stanford Univ, Dept Elect Engn, Stanford, CA 94305 USA