Hebei Key Laboratory of Optic-electronic Information and Materials;
College of Physics Science&Technology;
Hebei University;
Baoding 071002;
China;
California NanoSystems Institute;
University of California;
Los Angeles;
CA 90095;
USA;
State Key Laboratory of Modern Optical Instrumentation;
College of Optical Science and Engineering;
Zhejiang University;
Hangzhou 310058;
China;