1. Hefei National Laboratory for Physical Sciences at the Microscale University of Science and Technology of China Anhui, Hefei China
2. University of Science and Technology of China, Department of Precision Machinery and Precision Instrumentation Anhui, Hefei China
3. Key Laboratory of Precision Scientific Instrumentation of Anhui Higher Education Institutes, University of Science and Technology of China Anhui, Hefei China
4. Center for Biophotonics, University of California, Davis Sacramento California