1. SUPA, Institute of Photonics and Quantum Sciences, School of Engineering and Physical Sciences, Heriot-Watt University, Edinburgh, EH14 4AS, United Kingdom
2. School of Materials Science and Engineering, Chongqing Jiaotong University, Chongqing 400074, China
3. Centre for Photonics Research, Guilin University of Electronic Technology, Guilin, 541004, China
4. Laboratory of Weak Light Nonlinear Photonics Ministry of Education, School of Physics and Teda Applied Physics Institute, Nankai University, Tianjin 300071, China