1. GPL Photonics Laboratory, State Key Laboratory of Luminescence and Applications, Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences 1 , Changchun 130033, People's Republic of China
2. Department of Physics, Faculty of Science, University of Fayoum 2 , Fayoum 63514, Egypt
3. Lightwave Communications Research Group, Department of Electrical and Computer Engineering, School of Engineering, Democritus University of Thrace 3 , Xanthi 67100, Greece
4. The Institute of Optics, University of Rochester 4 , Rochester, New York 14627, USA