基于SESAM的掺铥锁模光纤激光器研究

Research on mode-locked thulium-doped fiber laser based on SESAM

目的:研究基于半导体可饱和吸收镜的大能量被动锁模掺铥光纤激光器的输出特性。方法:利用半导体可饱和吸收镜作为锁模器件,分别采用光纤全反射镜和光纤光栅搭建全光纤结构的被动锁模掺铥光纤激光器。结果:在采用光纤全反镜结构中,在泵浦功率为900 mW时,获得了中心波长为1945 nm,重复频率为9.80 MHz,单脉冲能量为9.46 nJ的锁模脉冲输出。用光纤光栅替换光纤全反射镜,大大降低了锁模阈值。在泵浦光为210 mW时,获得了中心波长为1941.5 nm的稳定锁模脉冲输出,功率稳定性RMS小于1%。结论:本文所搭建的锁模光纤激光器单脉冲能量可以达到nJ量级且锁模稳定。

Aims:This paper aims to study the output characters of high-energy passive mode-locked thulium-doped fiber laser based on a semiconductor saturable absorption mirror(SESAM).Methods:By using the SESAM,a passive mode-locked thulium-doped fiber laser with an all-fiber structure was constructed using an all-fiber reflector and a fiber Bragg grating(FBG),respectively.Results:In the fiber laser using an all-fiber reflector,the output pulses with a central wavelength of 1945 nm,a repetition frequency of 9.80 MHz and a single pulse energy of 9.46 nJ were obtained at the pump power of 900 mW.Based on this,another fiber laser structure in which the all-fiber reflector was replaced of a fiber Bragg grating(FBG)was built to reduce the threshold.The pulses with a central wavelength of 1941.5 nm were obtained at the pump power of 210 mW.The power stability of RMS was less than 1%which confirmed the high stability of this laser source.Conclusions:The single pulse energy of the mode-locked fiber laser thus constructed can scale up to nJ in a stable mode-locking operation.