Passively mode-locked 2-μm Tm:YAP laser with a double-wall carbon nanotube absorber

We report on a diode-pumped passively continuous wave （cw） mode-locked Tm：YAP laser with a double-wall carbon nanotube （DWCNT） absorber operating at a wavelength of 2023 nm for the first time, to the best our knowledge. The DWCNT absorber is fabricated on a hydrophilic quartz substrate by using the vertical evaporation technique. The output power is as high as 375 mW. A stable pulse train with a repetition rate of 72.26 MHz is generated with a highest single pulse energy of 5.2 μJ.

Interaction of a parabolic-shaped pulse pair in a passively mode-locked Yb-doped fiber laser

We numerically investigate the formation and interaction of a parabolic-shaped pulse pair in a passively mode-locked Yb-doped fiber laser. Based on a lumped model, the parabolic-shaped pulse pair is obtained by controlling the intercavity average dispersion and gain saturation energy, Moreover, pulse repulsive and attractive motion are also achieved with different pulse separations. Simulation results show that the phase shift plays an important role in pulse interaction, and the interaction is determined by the inter-cavity average dispersion and gain saturation energy, i.e., the strength of the interaction is proportional to the gain saturation energy, a stronger gain saturation energy will result in a higher interaction intensity. On the contrary, the increase of the inter-cavity dispersion will counterbalance some interaction force. The results also show that the interaction of a parabolic-shaped pulse pair has a larger interaction distance compared to conventional solitons.

Single output LD end-pumped passively mode-locked Nd:YVO_4 laser with semiconductor saturable absorber mirror

A quarter-wave plate and the thin film polarizer （TFP） are used for the LD end-pumped passively mode-locked Nd：YVO4 laser with semiconductor saturable absorber mirror （SESAM） to obtain a single beam output with a total power of 4.8 W. An optical-optical efficiency is achieved to be 24% for a stable CW mode-locking operation at 1064 nm, with a pulse repetition rate of 70 MHz and pulse width of 16 ps. The multipulse in the pulse sequence is eliminated for reaching a peak power as high as 4 kW.

Reflective graphene oxide absorber for passively mode-locked laser operating at nearly 1μm

A low cost and simply fabricated reflective graphene oxide is successfully made. By using this absorber, as well as an end reflector, we obtain a passively mode-locked Yb：LuYSiO5 laser operating at nearly 1 p,m. When the pump power is increased up to 5.73 W, stable mode locking is achieved. The central wavelength of the laser spectrum is 1043.2 nm with a pulse duration of 5.0 ps. When the pump power reaches 8.16 W, dual-wavelength mode locking laser pulses at 1036.3 nm and 1043.5 nm are simultaneously detected.

Bound soliton pulses in a passively mode-locked fibre ring laser

The bound solitons in a passively mode-locked fibre ring laser are observed and their formation mechanism is summarized in this paper. In order to obtain stable bound solitons, a strong CW laser field at the centre of the soliton spectral is necessary to suppress and synchronize the random soliton phase variations.

Observation of 550 MHz passively harmonic mode-locked pulses at L-band in an Er-doped fiber laser using carbon nanotubes film

We demonstrate a passively harmonic mode-locked（PHML） fiber laser operating at the L-band using carbon nanotubes polyvinyl alcohol（CNTs-PVA） film. Under suitable pump power and an appropriate setting of the polarization controller（PC）, the 54^（th） harmonic pulses at the L-band are generated with the side mode suppression ratio（SMSR） better than 44 dB and a repetition frequency of 503.37 MHz. Further increasing the pump power leads to a higher frequency of 550 MHz with compromised stability of 38.5 dB SMSR. To the best of our knowledge, this is the first demonstration on the generation of L-band PHML pulses from an Er-doped fiber laser based on CNTs.

A 1.7-ps pulse mode-locked Yb^(3+):Sc_2SiO_5 laser with a reflective graphene oxide saturable absorber

By using a reflective graphene oxide as saturable absorber, a diode-pumped passively mode-locked Yb^3＋：Sc2Si O5（Yb：SSO） laser has been demonstrated for the first time. Without extra negative dispersion compensation, the minimum pulse duration of 1.7 ps with a repetition rate of 94 MHz was obtained at the central wavelength of 1062.6 nm. The average output power amounts to 355 m W under the absorbed pump power of 15 W. The maximum peak power of the mode-locking laser is up to 2.2 k W, and the single pulse energy is 3.8nJ.

Tunable dual-wavelength passively mode-locked Yb-doped fiber laser using SESAM

In this linear-cavity passively mode-locked laser based on semiconductor saturable absorber mirror, an Ybdoped fiber is shared by two branch cavities as gain medium. These two cavities can respectively output single-wavelength pulse with the wavelength tuning range of 1 009.~1 057.6 nm and 1 011.6-1 052.6 nm by adjusting volume Bragg grating. When two cavities output pulses together, the dual-wavelength pulses with the maximum and minimum wavelength separation of 34.8 and 2.4 nm, respectively, are achieved by net gain equalization method to suppress mode competition at room temperature. The maximum pulse energies of dual-wavelength pulses are 0.47 and 0.33 nJ separately; their repetition rates are 11.39 and 11.41 MHz.

Low threshold high stability passively mode-locked laser performance of a disordered crystal:Nd^(3+):Gd_(0.5)Y_(2.5)Al_5O_(12)

A stable passively mode-locked laser of Nd^3＋：Gd0.5Y2.5Al5O12（Nd：GYAG） disordered crystal is experimentally investigated both using Z-type and W-type cavities with a semiconductor saturable absorbed mirror.The continuous-wave mode-locked threshold of the absorbed pump power is just 1.8 W.The maximum average output power is 210 mW,which is obtained at the absorbed pump power of 2.3 W.The pulse width is measured to be11.1 ps assuming a Gaussian shape.

Passive harmonic mode locking of gain-guided solitons in erbium-doped fiber lasers

We report the experimental observation of passive harmonic mode locking of gain-guided solitons in erbium-doped fiber lasers either made of purely normal dispersion fibers or operating in the net normal cavity dispersion regime. Harmonic-2 and harmonic-3 mode locking states of the gain-guided solitons with supermode suppression larger than 35 dB have been obtained.

Diode-pumped passively mode-locked femtosecond Yb:(Y_(0.9)La_(0.1) )_2O_3 ceramic laser

We experimentally demonstrate a diode-pumped passively mode-locked femtosecond laser with yb3＋-doped yttrium lanthanum oxide ceramic. Mode-locking is achieved by using a semiconductor saturable absorber mirror, and intraeavity dispersion is compensated by a pair of SF6 prisms. Laser pulses as short as 357 fs at a central wavelength of 1 075 nm are obtained. The maximum average output power is 670 mW under 4.5 W of pumping power with a slope efficiency of 20%. To the best of our knowledge, this is the shortest pulse generated from Yb-doped yttrium lanthanum oxide ceramic lasers with a sub-500 fs pulse duration.

Passively mode-locked Tm,Ho:YVO_4 laser based on a semiconductor saturable absorber mirror

We report the demonstration of passively continuous-wave mode-locking （CWML） of diode-pumped Tm,Ho：YVO4 laser using an InGaAs/GaAs multiple quantum-well （MQW） structure semiconductor as the saturable absorber. Stable mode-locking pulses at the central wavelength of 2 041 nm are obtained. The maximum output power is 151 roW. The pulse duration is 10.5 ps at the repetition rate of 64.3 MHz.

1064nm超短激光脉冲的锁模获取与特性分析

为了获得1064 nm皮秒级的超短激光脉冲,探究其波形和功率特征以及泵浦功率和腔长对锁模特性的影响,使用SESAM(半导体可饱和吸收镜)设计相应的W型折叠腔实验系统进行分析,获得了重复频率为92.25 MHz的稳定锁模脉冲。实验结果表明,在腔长不变时,若泵浦功率过低,则锁模不会启动,若泵浦功率过高,则会观察到调Q不稳定及多脉冲现象,且在产生锁模效应的泵浦功率范围内,锁模脉冲的平均功率大小和泵浦功率大小是呈正相关的;在泵浦功率大小一定时,锁模脉冲的波形对折叠腔腔长的变化极为敏感,不足1 mm的腔长变化都会使波形出现较大的抖动,只有在一个极小的范围内才会出现稳定的梳状波。

主被动调Q-锁模Nd∶YAG激光器的实验研究

对脉冲氙灯泵浦的调Q-锁模Nd：YAG固体激光器进行了实验研究.比较和分析了声光主动锁模、Cr^4＋ ：YAG晶体被动调Q-锁模以及这两种机制联合锁模情况下Nd：YAG激光器的输出特性.在Cr^4＋ ：YAG晶体被动调Q-锁模时得到了深度80%以上的锁模输出,但是锁模不完全,且波形和能量稳定性低,脉宽为1.9～3.6 ns.而主被动联合锁模克服了这一缺点,可获得幅值和能量抖动小于±5%、锁模深度100%、脉宽小于650ps、能量近300mJ的超短脉冲输出.

Influences of GVD on the characteristics of soliton in a passively mode-locked Er-doped fiber laser

In this paper, the characteristics of soliton in a passively mode-locked Er-doped fiber laser modeled by a non-distributed model are numerically investigated with the split-step Fourier method. Based on the analysis and model, sech2-shaped soliton is obtained by controlling the group velocity dispersion （GVD） and small-signal gain of the gain fiber. The law that the dispersion influences the characteristics of soliton in the mode-locked fiber laser is researched in net-cavity averaged anomalous dispersion regime.

基于SESAM的掺铥锁模光纤激光器研究

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。

饱和吸收体恢复时间对正交偏振耗散孤子的影响

偏振在脉冲锁模时,对其塑形和稳定起着至关重要的作用。本研究开发了一种用于产生正交偏振耗散孤子的被动锁模石墨烯光纤激光器的正交偏振数值模拟。重点是分析由偏振依赖的石墨烯微光纤饱和吸收体引起的净正常色散双折射腔对正交偏振孤子的影响。研究结果表明,这种饱和吸收体的恢复时间显著影响正交偏振耗散脉冲的特性,如能量、脉宽、时间带宽乘积和啁啾。结果显示,其恢复时间为120飞秒时最佳,产生两个具有大啁啾的正交偏振的窄耗散孤子脉冲,分别约为7.47 ps和8.06 ps。这对于开发紧凑、高功率、偏振耗散孤子光纤激光系统具有重要意义。

非线性偏振旋转锁模掺铥光纤激光器的多孤子输出理论研究

本文研究探讨了在非线性偏振旋转锁模掺铥光纤激光器中,孤子分子和类噪声脉冲的演化特性。理论研究表明,当激光器在负色散条件下工作且腔内参数得到恰当配置时,能够稳定产生锁模孤子脉冲。通过细调腔内的偏振状态并适度增加泵浦功率,可以实现孤子分子的输出。继续调整腔内条件,还能够获得类噪声脉冲。泵浦功率和偏振控制器的调整,通过改变腔内增益,成为产生多种多孤子模式的关键因素。这一发现为深入理解负色散区域内2μm波段锁模掺铥光纤激光器产生多孤子动态特性提供了有价值的参考。

主-被动对撞脉冲锁模钕玻璃振荡器研究

研制成功了一台主-被动对撞锁模的钕玻璃振荡器,激光脉冲宽度达到3ps强度起伏小于±6％,实验分析了影响振荡器稳定输出的几个原因。

复合二维材料GO-MoS_2锁模掺铒光纤激光器

为了提升MoS_2可饱和吸收体在脉冲激光器中的稳定性和工作性能,本论文采用氧化石墨烯(GO)作为胶体表面活性剂,通过LPE的方法剥离出少层MoS_2,并进一步开展了少层GO-MoS2用于掺铒光纤激光器(EDFL)锁模的实验研究。在实验中获得了中心波长为1558 nm,重复频率为7.86 MHz,脉宽为1.9 ps的稳定锁模脉冲激光。当泵浦功率为60.5 mW时,输出功率为0.48 mW,脉冲峰值功率为32.1 W。研究证明,采用这种方法制备的新型复合二维材料有利于保持少层MoS_2的稳定性,并且能提高MoS_2可饱和吸收体的损伤阈值,以获取更大脉冲能量的超快激光。