透/反复合双饱和吸收体被动锁模光纤激光器

Passively Mode-Locked Fiber Laser Based on Transmission/Reflection Composite Double Saturable Absorber

针对基于半导体可饱和吸收镜(SESAM)锁模光纤激光器脉冲底座宽和脉冲能量小的问题展开研究,报道了一种基于线型腔结构的透/反复合双饱和吸收体(SA)被动锁模超短脉冲光纤激光器。通过增加透射式SA的方式,增加光脉冲在腔内的一次振荡周期过程中通过透射式SA的次数,提高了吸收体对光脉冲前后沿的吸收,摆脱了因SESAM调制深度较低对脉冲宽度和单脉冲能量的影响,降低了因抽运功率过大产生的色散和非线性效应对光脉冲的影响,进一步提高了单脉冲能量。最终与相同调制深度的反射式单SESAM结构相比,复合双SA锁模结构的脉冲宽度从776fs缩短至732fs,单脉冲能量从2.08nJ提高到2.49nJ。

This paper studies the problem of wide pulse pedestal and low pulse energy of a single semiconductor saturable absorber （SESAM） mode-locked fiber laser, and reports a type of transmission/reflection composite double saturable absorber （SA） passively mode-locked ultrashort pulse fiber laser based on a linear cavity structure. By increasing the transmission of SA, the times of the light pulse passing through the transmissive SA increases in the process of one oscillation cycle. The absorbance of the absorber on the front and back edge of the optical pulse is improved. The effect of the SESAM lower modulation depth on the pulse width and single pulse energy is eliminated. The influence of dispersion and nonlinearity caused by excessive pump power is reduced, and the single pulse energy is further improved. Finally, compared to the single reflection SESAM structure with the same modulation depths, the pulse width of the composite double SA mode-locked structure is shortened from 776 fs to 732 fs and the single pulse energy is increased from 2.08 nJ to 2.49 rd.