Erbium-doped ZBLAN fiber laser pumped at 1.7 µm for emission at 2.8 µm
Junxiang Zhang, Rui Wang, Shijie Fu, Quan Sheng, Wenxin Xia, Lu Zhang, Wei Shi, Jianquan Yao
Abstract
In this paper, a novel, to the best of our knowledge, efficient pump scheme for an erbium-doped fluoride fiber laser with emission at 2.8 µm in the mid-infrared region is proposed and demonstrated. A singular pump source at 1.7 µm is used to excite Er 3+ ions from ground state 4 I 15/2 to lower laser level 4 I 13/2 , and then further boost the ions to 4 I 9/2 , where a non-radiation transition occurs for the Er 3+ ions to reach upper laser level 4 I 11/2 . This scheme can efficiently recycle ions on the lower laser level 4 I 13/2 by excited-state absorption, therefore realizing population inversion and enhancing laser efficiency. In our demonstration, a 660-mW laser output at 2.8 µm is achieved from a 1.7-µm core-pumped erbium-doped fluoride fiber laser, where the slope efficiency versus launched pump power is 23.7%. The proposed innovative pump scheme shows great potential to realize high-power, high-efficiency erbium-doped fiber lasers at 2.8 µm.