Numerical investigation of gain characteristics of Er3+/Yb3+ co-doped fiber amplifiers

In this work, a model for analyzing the gain characteristics of heavily Er³⁺/Yb³⁺ co-doped compact fiber amplifier is presented. Four-level rate equations and finite-difference beam propagation method are applied to simulate the optical field evolution along the active fiber. Based on this model, the influences of ion concentration, fiber length and pump power on the gain characteristics of Er³⁺/Yb³⁺ co-doped phosphate glass fiber amplifiers are theoretically investigated. Numerical results show that for a fiber length of 3.6 cm the internal gain can reach 27.2 dB with N _Er = 2.6 × 10²⁶ ions/m³ and N _Yb = 1.2 × 10²⁷ ions/m³ when pumped with 224 mW at 980 nm. The gain per centimeter is 7.56 dB/cm. The results can provide useful information to optimize the gain performance of these compact fiber amplifiers.     

Yb3+sensitized Er3+-doped waveguide amplifiers: a theoretical approach

Silicate and phosphate glass waveguide amplifiers doped with Er³⁺, and co-doped with Er³⁺/Yb³⁺ are theoretically studied. Configurations for core and core–cladding doped waveguide amplifiers are considered. It is shown that gain in the core–cladding doped amplifiers is considerably higher than core doped amplifiers. It is also shown that with input signal power up to 1 and 200mW pump power, a 12.5dB gain can be achieved in a 3cm long waveguide amplifier, with a noise figure of 3dB.     

被动锁模Yb3+光纤环形腔激光器的研究

采用974 nm半导体激光器作为泵浦源,超高掺杂Yb3+光纤作为增益介质,利用光纤的非线性偏振旋转效应,得到稳定的ps量级锁模光脉冲。泵浦功率220 mW时,激光器锁模阈值功率150 mW,输出功率26 mW,锁模光脉冲中心波长1 046 nm,3 dB带宽6.01 nm,20 dB带宽16 nm,脉宽22 ps,重复频率20 MHz。与同类光纤激光器相比,该激光器输出功率高,具有更好的稳定性。     

被动锁模Yb3+光纤环形腔激光器的研究

 采用974 nm半导体激光器作为泵浦源，超高掺杂Yb³⁺光纤作为增益介质，利用光纤的非线性偏振旋转效应，得到稳定的ps量级锁模光脉冲。泵浦功率220 mW时，激光器锁模阈值功率150 mW，输出功率26 mW，锁模光脉冲中心波长1 046 nm，3 dB带宽6.01 nm，20 dB带宽16 nm，脉宽22 ps，重复频率20 MHz。与同类光纤激光器相比，该激光器输出功率高，具有更好的稳定性。     

被动谐波锁模掺Yb3+光纤环形激光器

 利用光纤的非线性偏振旋转效应产生可饱和吸收体的锁模机制，从掺Yb³⁺光纤环形激光器中得到稳定高阶谐波锁模光脉冲。理论分析了工作于正色散区的掺Yb³⁺光纤环形激光器的特性。实验中观测到了掺Yb³⁺光纤环形激光器3种不同演化方式产生高阶锁模光脉冲。4阶谐波锁模脉冲（107.2 MHz重复频率）经过1 m长高掺杂Yb³⁺光纤放大器放大后产生了平均功率100 mW，脉宽22.8 ps的脉冲，最后经过光栅压缩得到了平均输出功率20 mW，脉宽307 fs，脉冲中心波长1 051.2 nm，带宽13.76 nm的激光。     

Yb3+-doped double-clad fiber laser with all fiber cavity

A novel all fiber cavity Yb3+-doped double-clad fiber laser (DCFL) based on two double-clad fiber (DCF)Bragg grating is presented. The fiber Bragg gratings (FBGs) as the input and output mirrors have been formed in Yb3+-doped DCF with the phase-mask method, and their reflectivities are 99% and 22%,respectively. When the input pump power is 417 mW, the maximum output power is 144 mW with linewidth ＜0.1 nm at the wavelength of 1.057μm, over 40-dB signal-to-noise ratio (SNR), and 50.8% slope efficiency.     

Raman fiber laser improvement by using Yb3+-doped fiber

We report here the efficiency improvement in a fiber Raman laser by splicing to it short pieces of 10000-ppm Yb³⁺-doped fibers. The amplified spontaneous emission produced by the doped fiber started the stimulated Raman scattering earlier than the spontaneous scattering in the 350-m silica-fiber cavity. In the best case, when splicing to the cavity 127 cm of doped fiber, the pump threshold decreased from 2.9 down to 1.27 W, representing a 56% improvement. This power was close to the theoretical minimum of 1.25 W for very long fibers. The second stokes signal (1175 nm) was only present when the doped fibers were inserted. At 4-W pump, the non-doped cavity delivered 2 W of first stokes signal (1117 nm) that represent a 50% efficiency compared to ～3 W delivered (～75%) when a 34-cm doped fiber was inserted. This improvement is intended to reduce the cost of fiber Raman lasers because less powerful sources or shorter fibers are necessary to produce more stokes components.     

Power distribution in Yb3+-doped double-cladding fiber laser

The distribution of pump light and signal light in Yb3+-doped double-cladding fiber laser is analyzed based on a rate equation model.Numerical simulation results are obtained.The numerical solution of the rate equation is shown to be in excellent agreement with the experimental data.     

掺Yb3+光纤激光器的特性与设计

 从速率方程出发，对波长为980nm的激光泵浦掺Yb^{3+光纤激光器进行数值模拟，全面分析激光器阈值功率、输出激光功率、增益等重要参数与泵浦功率、光纤长度、腔镜反射率、掺杂浓度等参量之间的关系。采用高浓度掺Yb3+光纤对环形光纤激光器做了初步实验研究，所得结论与实验模拟结果基本一致。}     

强泵浦下掺Yb3+双包层光纤激光器输出特性数值分析和实验研究

对强泵浦下线形腔掺Yb3+双包层光纤激光器输出特性进行了理论和实验研究。通过数值模拟,分析了泵浦光及激光在光纤中的分布、输出功率与泵浦功率的关系、光纤长度及腔镜反射率对激光输出功率的影响。在实验中,利用D型掺Yb3+双包层光纤获得了输出功率10 6W的光纤激光输出,斜率效率达86%。测量了在不同输出耦合条件下的输出功率、阈值泵浦功率和斜率效率,理论分析与实验结果基本一致,为进一步提高光纤激光器功率提供了理论和实验依据。     

Backward pumping kilowatt Yb3+-doped double-clad fiber laser

A ytterbium-doped double-clad fiber laser generating up to 1026 W of continuous-wave output power at 1085 nm with a slope efficiency of 74% by single-ended backward pumping configuration is reported. The core diameter was 20 μm with a low numerical aperture of 0.06, and a good beam quality (BPP < 1.8 mm mrad) is achieved without special mode selection methods. No undesirable roll-over was observed in output power with increasing pump power, and the maximum output power was limited by the available pump power. The instability of maximum output power was better than ±0.6%. Different pumping configurations were also compared in experiment, which shows good agreements with theoretical analyses.     

20 W single-mode Yb3+ -doped phosphate fiber laser

We report the demonstration of the first, to our knowledge, cladding-pumped continuous-wave Yb(3+)-doped phosphate-glass fiber laser. Phosphate hosts are of interest because they can be much more heavily doped than silica, and because of the possibility that they may have a higher photodarkening threshold. In an 84.6 cm double-clad fiber doped with 12 wt. % of Yb(2)O(3) and laser-diode pumped at 940 nm, nearly 20 W of single-mode 1.07 microm output power was generated with 60.2 W of absorbed pump power. The measured dependence of the output power on pump power is in excellent agreement with simulations.     

光纤光栅选频掺Yb3+双包层光纤激光器

利用相位掩模法，在D形内包层掺Yb3+双包层光纤一端直接写制出Bragg光栅，用作双包层光纤激光器的输出腔镜.试验得到了线宽为0.196nm，波长为1058.2nm，最高输出功率为570mW的稳定激光输出，解决了激光器中模式竞争造成的输出不稳定现象.从速率方程出发，对激光器的输出功率与抽运功率、光栅反射率的关系以及最佳光纤长度进行了理论分析，结果与实验符合很好. 关键词： 双包层光纤光栅 掺Yb3＋双包层光纤激光器 相位掩模 速率方程     

掺Yb3+双包层大模场面积光纤锁模激光器

报道了一种结构简单、运转稳定并可以输出高脉冲能量的被动锁模光纤激光器.激光器的增益介质为掺Yb3 双包层大模场面积光纤,具有非常低的非线性系数.利用非线性偏振旋转效应和半导体可饱和吸收镜结合实现自启动锁模,获得了平均功率为160 mW、重复频率为55.9 MHz(对应于3 nJ的单脉冲能量)、脉冲宽度为10.6 ps的激光脉冲输出.     

光纤光栅选频掺Yb3+双包层光纤激光器

利用相位掩模法 ,在D形内包层掺Yb3 双包层光纤一端直接写制出Bragg光栅 ,用作双包层光纤激光器的输出腔镜 .试验得到了线宽为 0 196nm ,波长为 10 5 8 2nm ,最高输出功率为 5 70mW的稳定激光输出 ,解决了激光器中模式竞争造成的输出不稳定现象 .从速率方程出发 ,对激光器的输出功率与抽运功率、光栅反射率的关系以及最佳光纤长度进行了理论分析 ,结果与实验符合很好     

Threshold characteristics analysis of one-end-pumped Yb3+-doped gain-guided and index-antiguided fiber laser

An exact analytical expression of the threshold pump power for the one-end-pumped Yb³⁺-doped gain-guided and index-antiguided (GG–IAG) fiber laser has been obtained by solving the improved rate equations (REs) with the additional leakage losses. The effects of Yb³⁺ concentration, fiber length, core radius and mirror reflectivity on the threshold pump power are discussed. After optimizing, the results show that the laser threshold of GG–IAG fiber laser can be greatly reduced while maintaining single mode oscillation. Compared to the numerical methods, the analytical expression has easy calculation and distinct results.     

Output characteristic of Yb3+-doped fiber laser at different temperatures

The output characteristics of Yb3+-doped fiber laser at different temperatures are investigated. When temperature is increased from 13 to 95 ℃, the center wavelength of laser changes from 1084.9 to 1096.3nm, the output laser power decreases from 0.95 to 0.58 W, and the slope efficiency drops from 30.7% to 25.5%.     

LD泵浦掺铥(Tm3+)光纤激光器的数值分析

首先从掺铥光纤激光器的速率方程和光传输方程出发，建立数学模型，通过Matlab软件进行数值计算，分析了泵浦光和激光沿光纤的分布以及各能级离子数的变化。在不同掺杂浓度下，研究了小信号增益与入纤泵浦功率的关系以及泵浦光和激光功率与增益介质长度的关系。在不同泵浦功率下，研究了输出功率与输出耦合镜反射率的关系。进一步对不同泵浦吸收系数，研究了斜率效率和泵浦阈值与光纤长度的关系。分析结果表明：存在最佳光纤长度和最佳耦合输出透过率，使得激光输出功率达到最佳值。     

LD泵浦掺铥(Tm3+)光纤激光器的数值分析

首先从掺铥光纤激光器的速率方程和光传输方程出发,建立数学模型,通过Matlab软件进行数值计算,分析了泵浦光和激光沿光纤的分布以及各能级离子数的变化.在不同掺杂浓度下,研究了小信号增益与入纤泵浦功率的关系以及泵浦光和激光功率与增益介质长度的关系.在不同泵浦功率下,研究了输出功率与输出耦合镜反射率的关系.进一步对不同泵浦吸收系数,研究了斜率效率和泵浦阈值与光纤长度的关系.分析结果表明存在最佳光纤长度和最佳耦合输出透过率,使得激光输出功率达到最佳值.     

全光纤超短脉冲掺Yb3+光纤环形激光器

讨论了自启动被动锁模掺Yb3+光纤环形激光器产生短脉冲的机理,并研制出全光纤结构超短脉冲掺Yb3+光纤环形激光器.采用两个976nm半导体激光器级联抽运作为抽运源,高掺杂浓度掺Yb3+光纤作为增益介质,利用光纤的非线性偏振旋转效应,得到自启动、十分稳定的ps量级锁模光脉冲.激光器锁模阈值功率260mW,输出功率25mW,锁模光脉冲中心波长1056nm,3dB带宽11.7nm,重复频率20MHz.与其他结构光纤激光器相比,这种全光纤结构具有更高的效率和更好的稳定性.