1. Institute of Laser and Optoelectronics Technology, Fujian Provincial Key Laboratory for Photonics Technology, Key Laboratory of OptoElectronic Science and Technology for Medicine of Ministry of Education, Fujian Normal University, Fuzhou 350007, P. R. China
2. Department of Colorectal Surgery, The Affiliated Union Hospital, Fujian Medical University, Fuzhou 350001, P. R. China