[1] Ioffe Phys Tech Inst RAS, St Petersburg 194021, Russia
[2] Beijing Univ Posts & Telecommun, Key Lab Informat Photon & Opt Commun, Minist Educ, Beijing 100876, Peoples R China
[3] St Petersburg Acad Univ RAS, St Petersburg 194021, Russia
[4] CNRS LPN, F-91460 Marcoussis, France
[5] CNRS, Dept OptoGaN, Inst Elect Fondamentale, UMR 8622, F-91405 Orsay, France