1. School of Optical and Electronic Information and Wuhan National Laboratory for Optoelectronics, Huazhong University of Science and Technology, 430074 Wuhan, China
2. Max-Planck Institute of Quantum Optics, Hans-Kopfermann-Str. 1, 85748 GarchingGermany
3. Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, 100190 Beijing, China
4. Ludwig Maximilian University of Munich, Am Coulombwall 1, 85748 Garching, Germany
5. School of Optics and Photonics, Beijing Institute of Technology, 100081 Beijing, China
6. TRUMPF Laser GmbH, Aichhalder Straße 39, D-78713 SchrambergGermany
7. Institut für Photonik, TU Wien, A-1040 Vienna, Austria
8. Helmut-Schmidt-Universität/Universität der Bundeswehr, 22043 HamburgGermany