(1. 中国计量大学 光学与电子科技学院, 杭州 310018;2. 广东工业大学 信息工程学院, 广州 510006)
(1. Institute of Optoelectronic Technology, China Jiliang University, Hangzhou 310018, CHN;2. School of Information Engineering, Guangdong University of Technology, Guangzhou 510006, CHN)
A tunable random fiber laser based on random grating and high reflection FBG is proposed. A 980nm pump light source is used to pump a 7m long erbium-doped fiber for gain amplification, and random feedback is provided by a random grating. The random grating is 7cm long and has about 10,000 refractive index modification points. These points are written point by point by the femtosecond laser and randomly distributed along the fiber direction. The distance between the two points is less than 10μm. At the same time, a semi-open cavity structure was formed by using a high-reflection FBG with a center wavelength of 1548nm to achieve random laser output. The experimentally measured pump threshold power is only 18mW, and the slope efficiency is as high as 13.2%. By changing the center wavelength of the FBG, the output laser wavelength can be tuned with a tuning range of 4.45nm (1548.04~1552.49nm). Thanks to the design of the semi-open laser cavity and the high gain of EDF, the entire system has the advantages of low threshold, high efficiency, and simple structure.