1. State Key Laboratory on Tunable Laser TechnologyMinistry of Industry and Information Technology Key Lab of Micro‐Nano Optoelectronic Information SystemShenzhen Graduate SchoolHarbin Institute of Technology Shenzhen 518055 P. R. China
2. State Key Lab for Mesoscopic Physics and Department of PhysicsPeking University Beijing 100871 P. R. China
3. Collaborative Innovation Center of Extreme OpticsShanxi University Taiyuan Shanxi 030006 P. R. China
4. Electrical Engineering DepartmentUniversity at BuffaloThe State University of New York Buffalo NY 14260 USA