石墨烯被动锁模全正色散掺镱光纤激光器中的暗脉冲及其谐波

报道了一种基于石墨烯被动锁模的全正色散掺镱环形光纤激光器. 在激光器腔中应用激光诱导沉积法制备的石墨烯可饱和吸收体, 通过调节抽运光功率和偏振控制器的角度分别得到了明脉冲及其二阶谐波, 暗明脉冲对和暗脉冲及其二、三阶谐波这三类不同的脉冲. 其中, 暗明脉冲对和暗脉冲在基于石墨烯被动锁模的掺镱光纤激光器实验中都是第一次被观察到. 本文根据实验结果结合模拟分析了暗脉冲的产生机理, 并研究对比了明脉冲谐波和暗脉冲谐波产生的原因.     

氧化石墨烯被动调Q掺铒光纤激光器

报道了基于氧化石墨烯的被动调Q掺铒光纤激光器。激光器采用环形腔结构,调Q器件为自制的氧化石墨烯可饱和吸收镜。泵浦功率在81~505 mW范围内时,得到了重复频率68~124 kHz的稳定的调Q脉冲输出,脉宽为0.47~1.60 s。由于泵浦功率限制,激光器最大输出功率为10 mW, 相应单脉冲能量为80.6 nJ。此种基于氧化石墨烯可饱和吸收体的被动调Q光纤激光器体积小、成本低廉、结构简单、稳定性高、光束质量高,具有广阔的应用前景。     

超长腔碳纳米管锁模多波长掺镱光纤激光器

报道了一种超长腔碳纳米管锁模多波长掺镱光纤激光器, 光纤激光器的总长度为1021.2 m. 实验得到了噪声型孤子和孤子雨两种类型的多波长锁模脉冲, 重复频率均为199.8 kHz. 孤子雨具有更高的输出功率和单脉冲能量, 分别为40.3 mW和201.5 nJ, 对应的脉冲宽度为102.5 ns.     

宽光谱全正色散锁模掺镱光纤激光器

介绍了一种全正色散宽光谱被动锁模掺镱光纤激光器,利用非线性偏振旋转技术实现全正色散掺镱光纤激光器的被动锁模.当泵浦功率输出为500mW时,激光脉冲输出功率大于139mW,重复频率约为28.1MHz,脉冲宽度为3.8ps.为了进一步研究全正色散光纤激光器的宽光谱输出特性,在腔内熔接50m单模光纤,同时去除双折射滤波片,在泵浦功率为500mW时,观察到稳定锁模单脉冲耗散孤子,光谱范围为1 005~1 140nm,输出激光脉冲最大平均功率为90mW,重复频率为3.58MHz,脉冲宽度为519ps.     

离子注入GaAs实现双包层掺镱光纤激光器被动调Q锁模

用离子注入的半绝缘GaAs晶片作为吸收体和输出镜，在双包层掺镱光纤激光器上实现了调Q锁模. 离子注入的能量为400keV的As+离子，注入剂量为1016/cm2，然后在600℃下退火20min. 当抽运功率为5W时, 脉冲平均输出功率为200mW, 调Q包络重复频率为50kHz, 半高宽为4μs，锁模脉冲重复频率为15MHz. 关键词： 离子注入GaAs 掺镱光纤激光器 被动调Q锁模     

脉冲泵浦掺镱双包层光纤激光器的动力学研究

对脉冲泵浦的掺镱双包层光纤激光器进行了实验研究.采用重复频率1-10 kHz、脉宽100 μs的976 nmLDs泵浦,实现了脉宽小于10 ns的稳定激光脉冲输出.并对该激光器的动力学过程进行了分析,首次提出了在脉冲泵浦光纤激光器中产生ns脉冲是瑞利散射和受激布里渊散射共同作用的结果.     

被动锁模掺饵光纤激光器的研究

利用光孤子压缩纠缠态进行量子通信，是量子通信走向实用化的重要途径，为产生光孤子压缩纠缠态，要有大功率的超短fs脉冲源。利用Cr^4＋：YAG激光器其结构比较复杂，若利用被动锁模fs光纤激光器，结构简单得多。在此之前，人们对被动锁模光纤激光器进行了大量研究。     

基于石墨烯可饱和吸收体的纳秒锁模掺铥光纤激光器

报道了一种基于石墨烯可饱和吸收体的纳秒锁模掺铥光纤激光器.该激光器采用环形腔结构,利用自制的三层石墨烯薄膜作为可饱和吸收体实现锁模.同时在腔内插入一个窄带光纤光栅,约束腔内起振的纵模数,适当调节抽运功率和偏振控制器的角度,得到了重复频率为3.8 MHz、脉宽在3.8—94.3 ns之间灵活可调的2μm纳秒锁模脉冲输出,整个脉宽调节范围超过90 ns.此外,由于获得的兆赫兹纳秒锁模脉冲时间带宽积在49—1119范围内,即存在强烈的啁啾,因而可作为2μm波段啁啾脉冲放大系统中的种子源使用.     

全正色散多波长被动锁模耗散孤子掺镱光纤激光器

报道了一种带有周期性双折射光纤滤波器的全正色散多波长被动锁模耗散孤子掺镱光纤激光器. 通过数值模拟发现加入滤波器后激光器能输出多波长耗散孤子脉冲, 调节滤波器带宽大小可以得到不同波长个数和波长间隔的多波长锁模耗散孤子脉冲. 在激光器产生的四波长和五波长耗散孤子脉冲中观察到了耗散孤子分子, 并且通过调节滤波器参数和饱和功率可以改变多波长脉冲中耗散孤子分子的个数和波长. 这是在被动锁模光纤激光器中首次实现包含有耗散孤子分子的多波长脉冲. 另外还在实验上实现了全正色散双波长被动锁模耗散孤子的产生. 关键词： 全正色散 耗散孤子 多波长脉冲 孤子分子     

自启动被动锁模掺饵光纤激光器的研究

在非线性光纤环形镜非线性开关效应和块状半导体波导饱和吸收效应的共同作用下，实现了掺饵光纤激光器的自启动被动锁模，获得了十分稳定的锁模脉冲序列，观察到高次谐频锁模脉冲输出。分析了非线性光纤环形镜的非线性开关反射特性。     

Tunable passively Q-switched ytterbium-doped fiber laser using MoWS2/rGO nanocomposite saturable absorber

We demonstrated a tunable Q-switched ytterbium-doped fiber laser (YDFL) using MoWS₂/rGO nanocomposite as passive saturable absorber. Further, the Mo_1?xW_xS₂/rGO nanosheets, with x proportion of 0.2, are synthesized using hydrothermal exfoliation technique. The proposed nanocomposite-PVA based thin film is fabricated by mixing the MoWS₂/rGO nanosheets with polyvinyl alcohol (PVA). The fabricated thin film is sandwiched between two fiber ferrules to realize the proposed saturable absorber (SA). Further, the proposed MoWS₂/rGO-PVA based thin film SA exhibits a fast relaxation time and a high damage threshold which are suitable to realize a Q-switched pulsed laser with a tunable wavelength range of 10?nm that extends from 1028?nm to 1038?nm. For the highest pump power of 267.4?mW, the generated Q-switched pulses exhibit a narrow pulse width of 1.22 μs, the pulse repetition rate of 90.4?kHz, the highest pulse energy of 2.13?nJ and its corresponding average power of 0.193?mW. To the best of author’s knowledge, this is the first realization of a tunable Q-switching fiber laser in a 1?μm wavelength using MoWS₂/rGO nanocomposite saturable absorber.     

石墨烯可调谐被动调Q掺铒光纤激光器

基于光学沉积方法,制备了石墨烯可饱和吸收体,并利用此可饱和吸收体搭建了环形腔结构的被动调Q掺铒光纤激光器,实现了稳定的调Q激光脉冲输出,其重复频率为5.1~14.2 kHz,最窄激光脉冲宽度为8 s,最大平均功率为162.3 W,且通过调节偏振控制器,中心波长在1556~1558 nm可调。     

Zinc-oxide/PDMS-clad tapered fiber saturable absorber for passively mode-locked erbium-doped fiber laser

We propose and demonstrate a passively mode-locked erbium-doped fiber laser(EDFL) based on zincoxide/polydimethylsiloxane(Zn O/PDMS) saturable absorber(SA) that evanescently interacts with the light on a tapered fiber. The Zn O/PDMS composite is coated on the whole surface of the tapered fiber to guarantee the maximum efficiency of the SA device, with a measured insertion loss of 0.87 d B and a modulation depth of 6.4%. The proposed laser can generate soliton mode-locking operation at a threshold power of 33.07 m W. The generated output pulse yields a repetition rate and pulse width of 9.77 MHz and 1.03 ps, respectively. These results indicate that the proposed Zn O/PDMS-clad tapered fiber could be useful as an efficient, compatible, and low-cost SA device for ultrafast laser applications.     

掺Yb3+双包层光纤激光器实验中的荧光分析

在研究掺Yb3+光纤激光器的实验中,发现伴生有可见区的荧光,用光谱仪测量发现该可见区荧光的波长分别为639.4 nm,520.7 nm,487 nm和474.8 nm,通过对比分析掺Yb3+光纤中杂质的能级结构,发现伴生的红、绿、蓝荧光由Yb3+与Pr3+合作产生,其荧光过程是由于Yb3+离子的能量转移给Pr3+,由Pr3+受激辐射产生的红、绿、蓝荧光.实验结果表明:掺Yb3+双包层光纤吸收泵浦光后产生的荧光是上转换的,这会导致光纤激光器激光能量转换效率的降低.     

Tunable double-clad ytterbium-doped fiber laser based on a double-pass Mach-Zehnder interferometer

We have demonstrated an adjustable double-clad Yb³⁺-doped fiber laser using a double-pass Mach-Zehnder interferometer. The laser is adjustable over a range of 40 nm from 1064 nm to 1104 nm. By adjusting the state of the polarization controller, which is placed in the double-pass Mach-Zehnder interferometer, we obtained central lasing wavelengths that can be accurately tuned with controllable spacing between different tunable wavelengths. The laser has a side mode suppression ratio of 42 dB, the 3 dB spectral width is less than 0.2 nm, and the slope efficiencies at 1068 nm, 1082 nm and 1098 nm are 23%, 32% and 26%, respectively. In addition, we have experimentally observed tunable multi-wavelengths lasing output.     

滤波位置相关的全正色散掺Yb3+锁模光纤激光器的实验研究

采用非线性偏振旋转锁模,构建了一种全正色散掺Yb³⁺光纤环形激光器.在该激光腔内采用了10 nm带宽的光纤滤波器提供附加的自振幅调制.通过改变滤波器在腔内的位置,实验证明了滤波器位置对高啁啾脉冲的整形过程起到重要的作用.在320 mW的抽运功率下,最终获得平均功率为922 mW,脉冲重复频率为266 MHz,脉冲宽度为62 ps的稳定脉冲输出,单脉冲能量达35 nJ的优化结果.通过数值模拟与实验结果的验证表明,两者相符很好. 关键词： 锁模光纤激光器 全正色散 滤波效应 高啁啾脉冲     

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.     

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

We numerically investigate the formation and interaction of 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 inter-cavity 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, the stronger gain saturation energy will result in 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 compare to the conventional solitons.     

Optical properties of ytterbium-doped tandem-pumped fiber oscillator

With the rapid development of ytterbium-doped fiber lasers, some obtrusive limitations on power scaling appeared. In order to avoid these problems, a scheme called tandem pumping is introduced into the fiber laser field. In this paper, the optical properties of an ytterbium-doped tandem-pumped fiber oscillator are presented. According to the oscillator profile, the proper gain fiber type and pump wavelength range are picked out, under the comprehensive consideration of laser conversion efficiency and beam quality. In addition, the photodarkening performances of tandem pumping lasers and conventional ones are compared based on practical application, with all possible impact parameters taken into account. Moreover, an all-fibered tandem-pumped oscillator centered at 1079.5 nm is built, in the way of clad pumping by a 1030-nm fiber laser. The laser power of the oscillator reaches 7 W, with an opto-optic efficiency of 82.4%.