1. Key Laboratory of In-fiber Integrated Optics of Ministry of Education, College of Science, Harbin Engineering University, Harbin, China
2. Xi'an Institute of Applied Optics, Xi'an, China
3. College of Science, Tianjin University of Technology, Tianjin, China
4. Optical Fibre Sensors Research Centre, Department of Electronic and Computer Engineering, University of Limerick, Limerick, Ireland
5. Photonics Research Center, Technological University Dublin, Dublin, Ireland