[1] Hong Kong Polytech Univ, Dept Appl Phys, Hung Hom, Hong Kong, Peoples R China
[2] Zhaoqing Univ, Coll Elect Informat & Mechatron Engn, Zhaoqing 526061, Guangdong, Peoples R China
[3] Chinese Univ Hong Kong, Sch Sci & Engn, Shenzhen 518172, Guangdong, Peoples R China