[1] Chinese Acad Sci, Inst Semicond, State Key Lab Integrated Optoelect, Beijing 100083, Peoples R China
[2] Univ Chinese Acad Sci, Beijing 100049, Peoples R China
[3] Beijing Univ Technol, Coll Microelect, Fac Informat Technol, Beijing 100124, Peoples R China
[4] Beijing Univ Posts & Telecommun, Sch Informat & Commun Engn, State Key Lab Informat Photon & Opt Commun, Beijing 100876, Peoples R China