1. National University of Defense Technology, College of Optoelectric Science and Engineering, Changsha, Hunan 410073, ChinabHunan Provincial Key Laboratory of High Energy Laser Technology, Changsha, Hunan 410073, ChinacHunan Provincial Collaborative Innovation Center of High Power Fiber Laser, Changsha, Hunan 410073, China
2. National University of Defense Technology, College of Optoelectric Science and Engineering, Changsha, Hunan 410073, ChinabHunan Provincial Key Laboratory of High Energy Laser Technology, Changsha, Hunan 410073, ChinacHunan Provincial Collaborative Innovation Center of High Power Fiber Laser, Changsha, Hunan 410073, ChinadShandong University, State Key Laboratory of Crystal Materials, Jinan 250100, China