[1] Natl Chiao Tung Univ, Dept Photon, Hsinchu, Taiwan
[2] Natl Chiao Tung Univ, Inst Electroopt Engn, Hsinchu, Taiwan
[3] Epistar Co Ltd, R&D Div, Hsinchu, Taiwan
[4] Natl Chiao Tung Univ, Inst Lighting & Energy Photon, Tainan, Taiwan
[5] Natl Chiao Tung Univ, Inst Elect, Hsinchu 30039, Taiwan