基于随机光栅的可调谐随机光纤激光器

Tunable Random Fiber Laser Based on Random Grating

摘要:

提出一种基于随机光栅与高反射布拉格光栅(FBG)相结合的可调谐随机光纤激光器。利用980nm泵浦光源泵浦一段7m长的掺铒光纤(EDF)进行增益放大,由随机光栅提供随机反馈。随机光栅长7cm,具有约10000个折射率修改点,这些点由飞秒激光逐点写入,并沿光纤方向随机分布,两点相邻间隔小于10μm。同时,利用中心波长为1548nm的高反射FBG来组成半开放腔结构,实现了随机激光的输出。实验测得的泵浦阈值功率仅为18mW,斜率效率高达13.2%,并通过改变FBG的中心波长,实现了输出激光波长的可调谐,调谐范围为4.45nm(1548.04~1552.49nm)。得益于半开放式激光腔的设计和EDF的高增益,整个系统具有阈值低、效率高、结构简单等优点。

Abstract:

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.