[1] Key Lab of In-Fiber Integrated Optics of Ministry of Education of China, Harbin Engineering University, Harbin,150001, China
[2] Key Laboratory of Optoelectronic Devices and Systems of Ministry of Education and Guangdong Province, College of Optoelectronic Engineering, Shenzhen University, Shenzhen,518060, China
[3] Optoelectronics Research Centre, University of Southampton, Southampton,SO17 1BJ, United Kingdom