1. State Key Laboratory of Precision Measuring Technology and InstrumentsTianjin University Tianjin P. R. China
2. Key Laboratory of the Ministry of Education for Optoelectronic Measurement Technology and InstrumentBeijing Information Science & Technology University Beijing P. R. China
3. Beijing Laboratory of Optical Fiber Sensing and SystemBeijing Information Science & Technology University Beijing P. R. China
4. Overseas Expertise Introduction Center for Discipline Innovation (‘‘111 Center’’)Beijing Information Science & Technology University Beijing P. R. China
5. Centre for Photonic Devices and SensorsUniversity of Cambridge Cambridge UK