Nonlinear polarization rotation-induced pulse shaping in a stretched-pulse ytterbium-doped fiber laser

We report on controllable pulse shaping in a Yb-doped stretched-pulse fiber laser followed by a high-power chirped pulse amplifier. We demonstrate that the pulses after an extra-cavity grating pair change their intensity profile from Lorentz to Gaussian and then to sech2 shapes by adjusting the intra-cavity polarization through a quarter-wave plate inside the fiber laser cavity. The laser pulses with different pulse shapes exhibit pulse-to-pulse amplitude fluctuation of -- 1.02%, while the sech2-shaped pulse train is provided with a more stable free-running repetition rate as a result of the stronger self-phase modulation in the fiber laser cavity than Lorentz- and Gaussian-shaped pulse trains.     

5 TW/40 fs级台式钛宝石激光系统研究

在TSA-25系统输出35 mJ,800 nm啁啾脉冲的基础上,建立了以钛宝石作为增益介质的二级啁啾脉冲放大(CPA)系统。使用0.6 J和1.6 J,532 nm,10 Hz Nd∶YAG激光抽运,输出脉冲能量达到500 mJ,经压缩脉冲宽度为41 fs,压缩器的能量转换效率为63%,峰值功率可达7.6 TW。通过对放大器系统的钛宝石晶体、抽运密度以及多通结构通道数的选择等实验,有效地提高了能量放大器的萃取效率。其主放大器能量萃取效率达到32%,整个系统占用尺寸不到10 m2。     

Efficient Laser-Diode End-Pumped Passively Q-Switched Mode-Locked Yb：LYSO Laser Based on SESAM

We report an efficient Q-switched laser action based on a semiconductor saturable absorber mirrors （SESAMs） as passively Q-switched laser starter and a Yb：LYSO alloyed crystal as gain material pumped directly by 974nm InGaAs laser diodes. The output pulse duration is measured to be about 7μs, while the average power and the repetition rate of the pulse chain are about 0.92 W and 6.2 kHz, respectively, under 12.5 W absorbed pumping power. The Q-switched mode-locked pulse train is also observed in this setup. The laser performance shows that Yb：LYSO is a promising laser gain medium for laser-diode pumped compact solid-state lasers.     

适用于亚10 fs的共心衍射无像差展宽器

在升级5TW/40fs钛宝石激光系统的过程中,伴随10fs种子源的使用,提出并研制了一种新型的共心衍射无像差展宽器和全能量压缩器。该展宽器的最大特点是通过平面镜反射使光束入射时所形成的衍射点与展宽后的还原点均在凹面镜的球心(即共心结构),凹面镜不存在其它同类方法中的成像问题,展宽函数中不涉及凹面镜的焦距和离轴量。该展宽器可将亚10fs的种子脉冲展宽到纳秒量级,且具有无像差、高带宽、结构紧凑、调整精度高等优点,适合100TW级超快激光系统中脉冲展宽。     

可编程声光色散滤波器在10 Hz飞秒再生放大系统中的应用

报道了在10 Hz飞秒再生放大超快激光系统中,运用可编程声光色散滤波器(AOPDF)对注入再生放大的种子光进行频谱整形和色散预补偿,使钛宝石激光系统输出光脉冲谱线半峰全宽由原来的38 nm展宽到66 nm,压缩后输出脉冲宽度从35 fs减小到20 fs。实验结果表明,利用可编程声光色散滤波器能够同时独立进行光谱整形和大范围内色散补偿的特性,可以有效抑制啁啾脉冲放大过程中存在的谱线增益窄化效应,补偿钛宝石激光系统中存在的残留色散。这为进一步研制小于20 fs,10 TW量级钛宝石激光系统奠定了基础。     

半导体激光器抽运新型高效、调谐Yb:LYSO激光器

报道了以掺Yb介质硅酸镥钇晶体为增益介质的激光行为.在自由运转的条件下,在1086 nm的中心波长处用2.5%的输出耦合镜得到7.8 W的连续激光输出,相应的斜效率为64%.利用SF14棱镜作为腔内调谐元件,激光输出的调谐范围为1014～1091 nm.     

半导体激光器抽运新型高效、调谐Yb∶LYSO激光器

报道了以掺Yb介质硅酸镥钇晶体为增益介质的激光行为。在自由运转的条件下,在1086 nm的中心波长处用2.5%的输出耦合镜得到7.8 W的连续激光输出,相应的斜效率为64%。利用SF14棱镜作为腔内调谐元件,激光输出的调谐范围为1014~1091 nm。     

Pump-induced carrier envelope offset frequency dynamics and stabilization of an Yb-doped fiber frequency comb

In this paper, we demonstrate a carrier envelope phase-stabilized Yb-doped fiber frequency comb seeding by a nonlinear-polarization-evolution（NPE） mode-locked laser at a repetition rate of 60 MHz with a pulse duration of 191 fs.The pump-induced carrier envelope offset frequency（ f0） nonlinear tuning is discussed and further explained by the spectrum shift of the laser pulse. Through the environmental noise suppression, the drift of the free-running f0 is reduced down to less than 3 MHz within an hour. By feedback control on the pump power with a self-made phase-lock loop（PLL）electronics the carrier envelope offset frequency is well phase-locked with a frequency jitter of 85 m Hz within an hour.     

双重复频率锁模Yb:YAG陶瓷激光器

近年来,双重复频率锁模激光器在诸如双光梳光谱和异步光学采样等应用领域吸引了广泛关注.基于单一激光腔的双梳系统能大大降低成本,简化系统结构,且性能优异.双重复频率锁模激光器为发展紧凑型和实用型双梳装置开辟了道路.本文报道了一种可用作双光梳光谱系统光源的双重复频率锁模Yb:YAG陶瓷激光器.该激光器基于半导体可饱和吸收镜锁模技术,采用双通道抽运结构,利用新型非水基流延成型制备的Yb:YAG透明陶瓷,在单一的五镜腔中,当吸收抽运光功率为5.6 W时,实现了自启动、稳定运转的双重复频率锁模脉冲Pulse1和Pulse2,其重复频率分别为448.918和448.923 MHz,重复频率差为5 kHz.在吸收抽运功率为7 W时,得到最大的总平均输出功率170 mW,其中Pulse1和Pulse2的功率分别为89和81 mW,相应的光谱宽度分别为1和1.16 nm.性能相似的双重复频率脉冲彼此间保持了良好的相干性,实验结果证明了双通道抽运在双重复频率锁模激光器应用中的可行性,此种新型双重复频率激光器在双光梳光谱和测距等领域具有较好的应用潜力.