1. State Key Laboratory of Transient Optics and Photonics, Xi’an Institute of Optics and Precision Mechanics of CAS, Xi’an 710119, P. R. China
2. University of Chinese Academy of Sciences, Beijing 100049, P. R. China
3. Department of Gastroenterology, Renmin Hospital of Wuhan University, Wuhan 430060, P. R. China
4. Research Center of Analytical Instrumentation, School of Mechanical Engineering, Sichuan University, Chengdu 610065, P. R. China