1State Key Laboratory of Modern Optical Instrumentation, Zhejiang University, Hangzhou 310027, China
2Key Laboratory of Specialty Fiber Optics and Optical Access Networks, Joint International Research Laboratory of Specialty Fiber Optics and Advanced Communication, Shanghai University, Shanghai 200444, China
3Center for Smart Structures & Materials, Department of Mechanical Engineering, Northwestern University, Evanston, Illinois 60208, USA