低阈值光纤激光器稳频特性研究

为了实现低阈值光纤激光器的频率稳定输出,设计了环形腔光纤激光器,以光纤光栅作为波长选择元件,在未泵浦光纤饱和吸收体和其锥形化结构的协同作用下实现激光纵模选择,获得了短光纤饱和吸收体长度下的单纵模激光稳定输出。介绍了未泵浦光纤饱和吸收体选频原理和锥形结构滤波原理,实验研究了不同光纤饱和吸收体长度下激光纵模特性和波长稳定性,以及锥形化光纤饱和吸收体的激光输出特性。实验表明,引入锥形化结构的饱和吸收体后,激光器能够稳定输出1545 nm波长的单纵模激光,并有效降低光纤激光器阈值至7.58 mW,采用延迟自外差方法测得该光纤激光器的线宽小于8 kHz。

Study on Frequency stabilization of low threshold fiber laser

In order to realize the stable output of a low-threshold fiber laser, a fiber ring laser is designed, which employs a fiber Bragg grating as the wavelength selector, and the laser longitudinal mode choice is realized under unpumped erbium-doped fiber saturable absorber and its tapered structure. The stable single-longituinal-mode laser output can be obtained under short fiber saturable absorber. The principles of fiber saturable absorber on frequency selection and tapered structure filtering are introduced. The characteristics of laser longitudinal modes and wavelength stability are studied under fiber saturable absorbers of different length, and the laser output characteristics of tapered fiber saturable absorber are investigated experimentally. The experimental results show that, after introducing the tapered fiber saturable absorber, the single-longitudinal-mode laser output can steadily be obtained at 1545 nm, and the threshold of the fiber laser can be effectively reduced down to 7.58 mW. The laser linewidth that is measured by the delayed self-heterodyne method is less than 8 kHz.