色散管理光纤锁模激光器在近零色散域的非线性优化

目前,飞秒激光脉冲因脉冲宽度窄和峰值功率高的特点被广泛运用在多种领域中。其中,色散管理光纤锁模激光器因其特有的腔内呼吸机制使输出的激光脉冲能量更高,光谱更宽、脉宽更窄。使用啁啾布拉格光纤光栅进行色散管理的光纤锁模激光器能够实现真正的全光纤结构,提升激光器的紧凑性和稳定性,因此基于啁啾布拉格光纤光栅进行色散管理的光纤锁模激光器具有更加实际的应用意义。采用数值模拟的方法,研究了基于啁啾布拉格光纤光栅进行色散管理的掺镱光纤锁模激光器中单模光纤在腔内的不同分布对脉冲动力学过程和输出脉冲参数的影响。系统分析了谐振腔内净色散值不同时,腔内单模光纤的分布对脉冲在腔内的动力学过程的影响。模拟结果表明,在腔内净色散值为负时,啁啾布拉格光纤光栅与增益光纤间的单模光纤越短,光纤激光器维持稳定单脉冲运行的最大泵浦强度更高且输出光谱更宽,从而能够获得脉宽更窄的去啁啾脉冲;腔内净色散值越接近零时,啁啾布拉格光纤光栅与增益光纤间的单模光纤长度对输出脉冲参数作用的影响越显著;腔内净色散值为正时,单模光纤在腔内的分布对输出脉冲影响逐渐减弱,优化单模光纤分布提升锁模激光器性能并不明显。最后,提出了一种通过改变单模光纤在腔内的分布来提高激光器输出性能的优化方法。     

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.     

6 MHz重频调谐范围的稳定锁模掺镱光纤激光器

针对精密测量的实际应用需求,开发了具有6 MHz重复频率调谐范围的掺镱锁模光纤激光器。该光纤激光器利用啁啾光纤光栅实现色散补偿,可以实现不同色散域的锁模。实验中,系统研究了不同腔内净色散对锁模激光器输出特性和稳定性的影响,发现当具有一定负腔内净色散时,在不同的重复频率下都可以输出相同的光谱,同时输出光谱具有较好的高斯型。根据以上研究,特殊设计了稳定的简化腔结构和空间延迟线,同时优化了腔参数,保证了大范围的重复频率调谐和稳定的锁模运转。当中心重复频率为26 MHz 时,调谐比率达到23%。激光器稳定输出平均功率为3.23 mW的飞秒激光脉冲,去啁啾后脉冲宽度为347 fs。基于此,将光纤锁模激光器重复频率锁定于铷原子钟,在1 s的平均时间内获得了2×10?10的艾伦方差。     

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.     

Ytterbium-doped fiber ring laser in multi-pulse operation

An Ytterbium-doped mode-locked fiber laser using the polarization sensitive isolator and polarization controllers (PC) is reported. In the normal dispersion, the fiber laser can oscillate at the multi-pulse states by adjusting the position of the PC. On the condition that the polarization state isn’t changed, the outputs of Ytterbium-doped mode-locked fiber laser change from single pulse to multi-pulse by increasing the pump power. The fiber laser can achieve different multi-pulse output by adjusting the PC1 and PC2 carefully.     

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.     

Broad-band high-repetition-rate source for spectrally sliced WDM

A uniform 35-nm-wide spectrum is generated by broadening the output from a 2.5-GHz mode-locked femtosecond fiber laser in dispersion shifted fiber. The obtained spectrum is suitable for spectral slicing and wavelength-division-multiplexed applications. The spectral broadening in dispersion shifted fiber is optimized as a function of the launched pulse chirp parameter     

超短脉冲掺Yb3 光纤激光器的多脉冲运转

报道了一种由偏振敏感的光隔离器(ISO)和偏振控制器(PC)构成的掺Yb3 光纤超短脉冲环形激光器,其在没有进行色散补偿的情况下,通过调节PC的方向,实现了稳定的锁模多脉冲运转.在偏振状态一定的情况下,随着抽运源功率的增加,光纤激光器输出经历单脉冲到多脉冲的改变,通过改变PC和抽运源的抽运电流,可实现不同的多脉冲输出.分析表明,多脉冲的产生主要是可饱和吸收体的过驱动引起的.     

基于色散控制的全光纤掺镱被动锁模激光器的设计与仿真

设计了一种能够输出超短脉冲作为激光种子源的全光纤掺镱被动锁模光纤激光器,并对其进行了数值仿真。为了得到满足设计要求的超短脉冲,使用了被动锁模技术和色散补偿技术。利用非线性偏振旋转技术实现被动锁模,并在环形腔中引入全固态光子带隙光纤对腔中的正色散进行补偿。通过仿真及优化,获得了脉宽为0.7 ps,能量为0.89 nJ 的脉冲序列。仿真结果表明,使用被动锁模技术和色散补偿技术有利于得到满足作为激光种子源设计要求的超短脉冲。     

High Fundamental Repetition Rate Fiber Lasers Operated in Strong Normal Dispersion Regime

We demonstrate a high fundamental repetition rate erbium-doped fiber ring laser operated in strong normal dispersion regime passively mode-locked by the nonlinear polarization rotation technique. A novel scheme of using a polarization beam splitter as both the pump input coupler and the fiber laser output coupler is employed to increase the repetition rate of the fiber laser. Gain-guided solitons with a fundamental repetition rate of 234 MHz and 1.11-ps pulsewidth are achieved from the ring laser cavity.      

Environmentally Stable Mode-Locked Fiber Laser With Dispersion Compensation by Index-Guided Photonic Crystal Fiber

We exploit the anomalous dispersion generated by an index-guided photonic crystal fiber (PCF) for dispersion compensation in an ytterbium fiber laser passively mode-locked with a semiconductor saturable absorber. A PCF, reasonably compatible with standard fiber, and a Faraday rotator in the cavity allow for robust all-fiber subpicosecond operation at 1 m, insensitive to environmental disturbance.     

主动锁模光纤环形激光器的新进展

在概述主动锁模光纤环形激光器主要特性的基础上,介绍了实现主动锁模的3种技术方案：基于调制器的主动锁模光纤激光器、用半导体激光器作调制器的主动锁模光纤激光器和注入型主动锁模光纤激光器。最后主要讨论了有理数谐波锁模光纤激光器、多波长主动锁模光纤激光器和光子晶体光纤激光器的最新进展,同时指出了当前主动锁模光纤激光器研究的重点。     

Round-trip time and dispersion optimization in a dual-wavelengthactively mode-locked Er-doped fiber laser including nonchirped fiberBragg gratings

Round-trip time and intracavity dispersion were optimized in a dual-wavelength actively mode-locked Er-doped fiber laser including two nonchirped fiber Bragg gratings. This optimization allowed to generate nearly transform-limited pulses as short as 16 and 13 ps at 1547 and 1562 nm, respectively, at a 3-GHz repetition rate only limited by the modulator bandwidth. In the experiment, the round-trip time difference between pulses at two wavelengths was adjusted using a fiber stretcher. Intracavity dispersion was managed at each wavelength separately     

高次谐波锁模飞秒掺镱光纤激光器的噪声情况

高重复频率的飞秒激光在高速激光测距和三维成像等领域有着非常重要的作用。其中基于飞秒光纤激光器的高次谐波锁模是获得GHz量级以上高重复频率脉冲的重要手段之一。基于含腔内光栅对色散补偿的非线性偏振旋转（NPR）锁模的掺镱（Yb）光纤激光器,在180 mW泵浦光时获得了稳定的143 MHz基频锁模脉冲序列,当泵浦光功率升至1 W时获得了最高20次谐波（2.86 GHz）锁模脉冲序列输出。系统地对比研究了基频锁模与高次谐锁模状态下,脉冲重复频率精密锁定后的艾伦偏差和相位噪声,7次谐波锁模状态下重复频率锁定精度能够保持在10?13 Hz@1 s的稳定度,为高次谐波锁模飞秒激光脉冲序列用于精密测量提供了实验依据。     

A universal fiber-optic (UFO) measurement system based on a near-IR fiber Raman laser

A universal fiber-optic measurement system, which is useful for measuring loss and dispersion in the1.06-1.6 mum wavelength region, is described. The source is a silica fiber Raman laser pumped by a mode-locked andQ-switched Nd:YAG laser at 1.06 μm. Subnanosecond multiple-Stokes pulses in the1.1-1.6 mum wavelength region are generated in a low-loss single-mode silica fiber. The use of this near-infrared fiber Raman laser for characterizing various transmission properties of single and multimode test fibers is demonstrated. Loss spectra, intramodal dispersion, and intermodal dispersion data are obtained in the wavelength region of minimum loss and minimum material dispersion for silica fibers.     

High-energy femtosecond pulses from an ytterbium-doped fiber laser with a new cavity design

A new architecture which is based on the chirped pulse amplification scheme is proposed to increase the pulse energy of the mode-locked fiber laser. The idea was applied to a passively mode-locked laser using an ytterbium (Yb/sup 3+/)-doped double-clad silica fiber. Mode-locking was achieved by nonlinear polarization evolution associated to frequency-shifted feedback technique for self-starting. A compressor and a stretcher, based on diffraction gratings, permitted us to manage the dispersion and to reduce the pulse power in the fiber. The laser delivered chirped pulses at 1050 nm with 11.8-nJ energy at a 9.3-MHz repetition rate (110-mW average power) which were subsequently compressed to 196-fs duration.     

超宽光谱类噪声脉冲光纤激光器

报道了一种全光纤超宽带光谱的类噪声脉冲锁模光纤激光器。为了加宽锁模光谱,利用腔内色散管理和非线性技术,使在58m腔内具有小的反常色散,平均色散系数为0.12 ps/nm/km。实验获得了超过1300nm--1750nm超宽带光谱锁模类噪声脉冲,光谱20-dB带宽达到362nm,3-dB带宽达到102nm。类噪声脉冲的光谱宽度远超过掺铒光纤的增益带宽。     

可调谐全正色散掺镱光纤激光器

利用相位长周期光纤光栅作为光谱滤波器,熔接于全正色散掺镱光纤激光系统中,从而实现了具有波长可调谐的连续激光输出和被动锁模激光脉冲输出,可调谐激光波长范围分别为11.4 nm和10.5 nm.通过调节偏振片改变激光腔内的偏振状态,输出锁模脉冲实现脉冲宽度的可调谐,其调谐范围为3.6~1.2 ns.在530 mW的最大泵浦功率下,得到了重复频率为2.5 MHz、最大单脉冲能量为38.9 nJ的锁模脉冲输出和最大输出功率为124 mW的连续激光输出.     

Study on the chaotic dynamics of the mode-locked fiber ring laser

In this paper, we study the chaotic dynamics of the mode-locked fiber laser by numerical simulation. The structures of the passively mode-locked fiber laser and the actively mode-locked fiber laser are studied by modeling and analysis. By appropriately adjusting the small signal gain of the optical fiber amplifier, we observe the period-doubling bifurcations and route to chaos in the passively mode-locked fiber laser based on nonlinear polarization rotation effect. Chaos in the actively mode-locked erbium-doped fiber laser is obtained by adjusting the elliptic modulus parameter of the active modulator and the intra-cavity length. Simulation results have theoretical significance for the practical application of chaotic soliton communication.     

光纤中超连续脉冲的频谱展宽

为了产生高重复频率的多波长短光脉冲,利用锁模掺铒光纤激光器作为抽运光源,对色散位移光纤中的超连续脉冲进行了实验研究,成功实现了输出脉冲的频谱展宽.实验也发现,制约这个实验结果的主要因素是光纤激光器的输出脉冲的稳定性不够和功率不高.