Study on parameter optimization in a passively mode-locked Erbium-doped fiber laser

Optical soliton communication is the frontier research topic of optical fiber communication. In this paper, we study optical solitons generated by passively mode-locked Erbium-doped (Er-doped) fiber (EDF) laser. We analyze the variation of nonlinear equilibrium point parameter N of the passively mode-locked EDF laser in the role of group-velocity dispersion (GVD) and small-signal gain, and adjusting system parameter N is as close as to possible to 1. The ground state first-order optical soliton which generated through system parameter optimization of the passively mode-locked EDF laser will improve the efficiency and stability of optical soliton communication system. The research of this paper will have provided the theoretical foundation of parameter optimization in a passively mode-locked EDF laser. And it will be possible for the passively mode-locked fiber laser in optical fiber communication system to be applied from the laboratory stage to the practical application.     

一种全自动调节的锁模光纤激光器

通过在非线性偏振旋转环形腔中引入一种全光纤化的角度可调的起偏器,简化了被动锁模光纤激光器的结构,通过调节环形腔内的光纤起偏器和1/4波片的角度就能够实现锁模脉冲的输出。基于此简化结构,引入基于单片机的触发反馈电路,控制偏振片和波片的旋转状态,实现了腔内锁模脉冲的自动调节输出,得到平均功率为8mW的、重复频率为5.6 MHz的全自动锁模脉冲稳态输出。     

基于饱和吸收镜的被动锁模掺铒光纤激光器

为了研究基于半导体可饱和吸收镜的被动锁模光纤激光器的输出特性,采用1480nm的半导体激光器作为抽运源,利用掺铒光纤作为增益介质,以及光纤环行器、偏振控制器、波分复用器和耦合器等构成了环形腔结构的被动锁模光纤激光器。实验中获得了峰值波长1586nm、光谱宽度4.8nm、重复频率11.2MHz、最大平均输出功率8.4mW的稳定锁模激光脉冲输出。结果表明,调整光纤偏振控制器会使光纤激光器输出脉冲的时域波形略微发生变化,在实际应用中需要注意偏振态变化对锁模光纤激光器输出脉冲时域特性的影响。这一结果对于半导体可饱和吸收镜在被动锁模光纤激光器中的应用及其特性具有一定帮助。     

Multimode effects on the evolution and long-term stability of apassively mode-locked laser under pulsed injection locking

A multidimensional extension of the injection locking of CW lasers has been recently presented and experimentally verified when both a passively and an actively mode-locked laser were locked to injected coherent pulse trains. Harmonic injection locking of a passively mode-locked laser, where a subset of the laser cavity modes were locked to the injected signal, was also recently realized in a fiber laser to yield trains of 6-ps pulses at rates of up to 40 GHz. In this paper, the multimode injection-locking process is addressed with an emphasis on the long-term dynamics of the laser, pulse buildup under injection locking, memory effects, noise mechanism as well as potential applications, e.g., optical signal regeneration. Using a recently introduced formalism for describing passively mode-locked lasers, the experimental results are compared to numerical simulations     

Output characteristics of optical solitons in a passively mode-locked Yb-doped fiber laser

In this paper, we studied the output characteristics of optical soliton in a passively mode-locked ytterbium (Yb)-doped fiber laser by numerical simulation. The structure of the passively mode-locked Yb-doped fiber laser was studied by modeling and analysis. The influence of the inter-cavity average group velocity dispersion on pulse width, pulse peak power and single pulse energy of optical soliton and self-similar pulse was investigated. Simulation results were very instructive for the practical application of the passiavely mode-locked Yb-doped fiber lasers.     

Influences of finite gain bandwidth on dissipative solitons in passively mode-locked Er-doped fiber laser

Dissipative solitons in the passively mode-locked fiber lasers based on the gain medium of erbium-doped (Er-doped) fiber have attracted a lot of interest in recent years. In this paper, we study the influences of finite gain bandwidth on dissipative solitons in passively mode-locked Er-doped fiber laser. We investigate the influences of the finite gain bandwidth on pulse duration, pulse peak power and single pulse energy of dissipative solitons. The results show that gain bandwidth of the gain medium has influence on dissipative soliton characteristics in passively mode-locked Er-doped fiber laser. The research in this paper has important theoretical and practical significance.     

Harmonic mode-locking using regenerative phase modulation

In this letter, we report stable operation of a 1-GHz passively modelocked fiber laser synchronized by regenerative phase modulation. The minimum pulsewidth obtained was 600 fs and the laser amplitude noise was typical of low-noise passively mode-locked fiber lasers     

Er-Yb femtosecond ring fiber oscillator with 1.1-W average power and GHz repetition rates

We report an all-fiber passively mode-locked femtosecond laser oscillator based on the heavily doped Er-Yb phosphate-glass active fiber. Only 20 cm of the gain fiber is sufficient to produce as much as 1.1 W of average output power at 1.5 /spl mu/m directly from the oscillator. The laser can be harmonically mode-locked at repetition rates ranging from 1.7 to 7.2 GHz by adjusting the polarization bias in the cavity. The pulsewidth varies from 300 to 570 fs at the lowest and the highest repetition rate, respectively, and the maximum peak pulse power exceeds 1 kW.     

熔锥光纤倏逝场作用石墨烯双波长锁模掺镱光纤激光器

报道了利用熔锥光纤石墨烯饱和吸收体实现1μm波段的双波长锁模掺镱光纤激光器(YDFL)。利用光学诱导沉积法,将水溶液中的石墨烯纳米复合物在光倏逝场的作用下沉积至熔锥光纤的锥腰部位。该石墨烯熔锥光纤器件作为可饱和吸收锁模部件具有制作灵活、全光纤结构以及高损伤阈值等优点。基于该器件的可饱和吸收及腔内双折射滤波特性,通过调节偏振控制器优化激光腔内偏振特性,实现了稳定的YDFL双波长锁模。该激光器的两个锁模波长分别为1034.77nm和1038.85nm,二次谐波锁模重复频率为1.09MHz,腔内单脉冲能量最大可达35nJ。     

光谱边带测量法实现的色散匹配光纤激光器

在基于非线性偏振旋转效应的被动锁模光纤激光器中,利用测量脉冲光谱边带的方法计算腔内总色散,通过改变腔内普通单模光纤(SMF)的长度实现色散匹配,从而获得了重复频率为25 MHz、脉宽为520.5 fs、中心波长为1558.4 nm和3 dB带宽为29.5 nm的超短脉冲,输出功率为1.81 mW.在实现最佳色散匹配的条件下,对锁模脉冲的分裂、连续光波与孤子脉冲共存以及稳定的谐波锁模现象进行了实验研究和分析.     

LD抽运锁模Nd:YAG激光器研究

利用Cr4+:YAG和声光锁模器联合对光纤耦合LD抽运Nd:YAG激光器进行主被动锁模,比较和分析了Cr4+:YAG被动锁模,声光锁模器主动锁模及两者联合主被动锁模三种情况下平均输出功率的特性,结果表明主被动联合锁模克服了主动锁模稳定性差、被动锁模输出功率低、锁模不完全的缺点,得到幅值和能量抖动小于±6％、锁模深度100％、脉宽小于410ps、输出平均功率290mW的绿光锁模脉冲。     

基于半导体可饱和吸收镜的可调谐光纤激光器

为了实现锁模光纤激光器的波长可调谐, 采用半导体可饱和吸收镜(SESAM), 搭建了环形腔被动锁模掺镱光纤激光器。在腔内无偏振控制器及可调谐滤波器等器件的前提下, 通过改变光纤跳线端面至SESAM的距离, 实现光谱在1029.5nm~1042.7nm之间的稳定可调谐, 基频重复频率为18.0MHz, 脉冲宽度为130ps, 锁模脉冲信噪比达44dB。结果表明, 该锁模光纤激光器具有较高的信噪比及较宽的可调谐范围。该研究为可调谐被动锁模光纤激光器的研制提供了重要的参考价值。     

Two Different Operation Regimes of Fiber Laser Based on Nonlinear Polarization Rotation: Passive Mode-Locking and Multiwavelength Emission

We have proposed and demonstrated a nonlinear polarization-rotation-based fiber laser with two different operation states: passive mode-locking and multiwavelength emission. The intensity-dependent transmission or loss induced by nonlinear polarization rotation accounts for the distinct operation regimes. Our experiment results indicate that both passively mode-locked pulses and continuous-wave multiwavelength can be generated from the same fiber laser just through adjusting polarizations. Another characteristic of the current multiwavelength laser is that the used periodic filter is a birefringence fiber filter, which facilitates all-fiber integration of the fiber laser, so it is a potential multifunction laser source with all-fiber configuration and convenient manipulation.     

可调谐被动锁模掺铥光纤激光器

为了实现波长可调谐被动锁模掺铥光纤激光器，提出了基于激光腔随机双折射效应通过调节激光偏振态来改变被动锁模掺铥光纤激光器的工作波长的方法，并进行了原理分析和实验验证。结果表明，调节偏振控制器可实现在2010nm，2019nm，2024nm，2050nm等多个中心波长处的锁模脉冲输出，同时在单个中心波长附近，还可以精密调谐。这种可调谐锁模激光器结构简单、可调谐性好，对光通信、超快光学、医学、遥感技术和雷达等应用中光源的选择有一定的参考价值。     

调Q锁模类噪声方波脉冲掺铒光纤激光器

对基于非线性偏振旋转技术的L波段掺铒被动锁模光纤激光器中产生调Q锁模类噪声方波脉冲进行了实验研究。该类型脉冲中调Q包络内部包含的脉冲是基频方波,通过自相关迹证实该方波为类噪声脉冲。为了容易实现类噪声方波脉冲输出,将一段250 m普通单模光纤引进激光腔内。适当调节腔内的偏振控制器和泵浦功率,获得了基频为778.21 kHz的连续波锁模类噪声方波脉冲和由3.81 kHz可调谐到9.01 kHz的重复频率,单个调Q包络最高能量为1.06 J的调Q锁模类噪声方波脉冲。研究结果有利于进一步理解被动锁模光纤激光器中类噪声脉冲和调Q锁模的机理和特性。     

Novel method to simultaneously compress pulses and suppresssupermode noise in actively mode-locked fiber ring laser

Nonlinear polarization rotation is used to compress pulses or suppress supermode noise in mode-locked fiber lasers at different situations. In this letter, we propose a novel method to simultaneously realize the above two effects by exploiting nonlinear polarization rotation in actively mode-locked fiber ring laser at a special state. A simple model derived by theoretical analysis is given to explain this phenomenon. We have also investigated the different transmission situations of nonlinear polarization rotation in the 10-GHz actively mode-locked fiber ring laser. Experimental observations agree well with theoretical predictions     

基于SESAM的全光纤被动锁模光纤激光器

研究实现了一种主振荡功率放大（MOPA）结构的高功率全光纤皮秒级被动锁模掺镱（Yb3+）光纤激光器。种子源为基于半导体可饱和吸收镜（SESAM）的锁模光纤激光器,其为线性腔结构,输出功率为5.97 mW;预放大级采用单模掺镱光纤进行放大,之后经过4倍重复频率倍增系统和两级双包层掺镱光纤放大器,最终实现了平均功率74.3 W,中心波长1063.4 nm,脉冲宽度7.0 ps,重复频率68 MHz的锁模脉冲激光输出。实验中通过对种子光的处理和光纤长度的控制,未出现受激布里渊散射（SBS）、受激拉曼散射（SRS）等非线性效应。     

利用NALM结构的被动锁模掺铒光纤激光器的研究

为了研究光纤中的非线性效应对锁模脉冲的影响,采用非线性放大环镜来实现被动锁模,在分析非线性放大环镜传输特性理论的基础上,对被动锁模掺铒光纤激光器进行了相关的实验研究。实验中观察到了重复频率为280.2MHz、中心波长是1556.235nm、线宽是0.4nm的稳定的锁模脉冲现象。研究结果对更深入地了解被动锁模产生现象、进一步开展后续研究具有极其重要的意义。     

石墨烯被动锁模谐波阶数可调的掺铒光纤孤子激光器

采用石墨烯被动锁模的掺Er光纤(EDF)环形腔,获得稳定的谐波阶数可调的孤子脉冲激光。通过调节EDF环形腔中的偏振控制器(PC)改变光腔损耗,实现了锁模谐波从一阶至四阶的可控运转。连续锁模基频重复频率为3.873MHz,中心波长为1 557.6nm,谱线宽度为4.5nm,有明显孤子边带,信噪比(SNR)约为45dB,二、三和四次谐波锁模脉冲重复频率分别为7.745、11.618和15.491MHz。本文的实验结果可用工作于反常色散区锁模激光器的多孤子形成机理来解释。     

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.