1.ICT Research Center,Key Lab of Optoelectronic Tech. & Sys. of the EMC,Chongqing University,Chongqing 400044,China 2.College of Mathematics and Physics,Chongqing University,Chongqing 400044,China 3.Shandong Machinery(Group) Co. ltd,Zibo,Shandong 255201,China