1. State Key Laboratory of High-Power Semiconductor Laser, Changchun University of Science and Technology, Changchun, China
2. Suzhou Institute of Nano-Tech and Nano-Bionics, Chinese Academy of Sciences, Suzhou, Jiangsu, China
3. School of Science and Engineering, The Chinese University of Hong Kong, Shenzhen, Guangdong, P.R. China
4. Key Laboratory for Photonic and Electronic Bandgap Materials, Ministry of Education, School of Physics and Electronic Engineering, Harbin Normal University, Harbin, China