[1] City Univ Hong Kong, Dept Elect Engn, Kowloon, Hong Kong 999077, Peoples R China
[2] Great Bay Univ, Sch Phys Sci, Dongguan 523000, Peoples R China
[3] Great Bay Inst Adv Study, Dongguan 523000, Peoples R China
[4] City Univ Hong Kong, State Key Lab Terahertz & Millimeter Waves, Kowloon, Hong Kong 999077, Peoples R China
[5] City Univ Hong Kong, Ctr Biosyst Neurosci & Nanotechnol, Kowloon, Hong Kong 999077, Peoples R China