[1] Hebei Univ, Key Lab Optoelect Informat Mat Hebei Prov, Key Lab Digital Med Engn Hebei Prov, Coll Electron & Informat Engn, Baoding 071002, Peoples R China
[2] Southern Illinois Univ Carbondale, Dept Elect & Comp Engn, Carbondale, IL 62901 USA
[3] Natl Univ Singapore, Dept Mat Sci & Engn, Singapore 117576, Singapore