1. Key Laboratory of Advanced Transducers and Intelligent Control System; Ministry of Education; Taiyuan University of Technology; Taiyuan 030024 China
2. Institute of Optoelectronic Engineering; College of Physics and Optoelectronics; Taiyuan University of Technology; Taiyuan 030024 China
3. Clarendon Laboratory; University of Oxford; Parks Road Oxford OX1 3PU UK
4. State Key Laboratory of Quantum Optics and Quantum Optics Devices; Institute of Opto-Electronics; Shanxi University; Taiyuan 030006 China