1. Department of Mechanical and Aerospace Engineering, Hong Kong University of Science and Technology, Clear Water Bay, Hong Kong, China
2. Department of Mechanical Engineering, City University of Hong Kong, Hong Kong, China
3. School of Optical and Electronic Information, Engineering Research Center for Functional Ceramic MOE and Wuhan National Laboratory for Optoelectronics, Huazhong University of Science and Technology, Wuhan 430074, China