1. State Key Laboratory on Tunable Laser Technology; Ministry of Industry and Information Technology Key Lab of Micro-Nano Optoelectronic Information System; Shenzhen Graduate School; Harbin Institute of Technology; Shenzhen 518055 China
2. Department of Applied Physics; Chongqiong University; Chongqing 404100 P. R. China
3. State Key Lab for Mesoscopic Physics and Department of Physics; Peking University; Beijing 100871 P. R. China