Noise-like rectangular pulses in a mode-locked double-clad Er:Yb laser with a record pulse energy

Generation of noise-like rectangular pulse was investigated systematically in an Er–Yb co-doped fiber laser based on an intra-cavity coupler with different coupling ratios.When the coupling ratio was 5/95,stable mode-locked pulses could be obtained with the pulse packet duration tunable from 4.86 ns to 80 ns.The repetition frequency was 1.186 MHz with the output spectrum centered at 1.6μm.The average output power and single pulse energy reached a record 1.43 W and1.21μJ,respectively.Pulse characteristics under different coupling ratios(5/95,10/90,20/80,30/70,40/60)were also presented and discussed.

Er^(3+)/Yb^(3+)共掺光纤激光器中能量上转换的抑制

通过对掺Er3+和Er3+/Yb3+共掺光纤激光器的输出功率进行数值模拟发现 :高浓度的Er3+/Yb3+共掺光纤激光器的最大量子转换效率比同等浓度下的掺Er3+光纤激光器的最大量子转换效率高出一倍。说明由于Yb3+的加入 ,Er3+/Yb3+共掺光纤激光器有效地抑制了能量上转换 。

双包层Er^(3+)/Yb^(3+)共掺光纤激光器的实验研究

通过采用长度为 2m、入纤功率为 1W的双包层Er3 + /Yb3 + 共掺光纤作为增益介质所进行的双包层Er3 + /Yb3 + 共掺光纤激光器的实验 ,得到了波长为 15 6 3.5 96nm、功率为 2 4

双包层Er^(3+)/Yb^(3+)共掺光纤激光器稳态特性的分析

对 98 0nm泵浦光泵浦双包层Er3 + /Yb3 + 共掺光纤激光器进行了数值模拟 ,分析了泵浦光与激光在双包层Er3 + /Yb3 + 共掺光纤中的分布情况、输出功率与泵浦功率的关系、光纤长度与腔镜反射率对输出激光功率的影响 ,计算的最大斜效率为 5 6 .3%,接近于理论计算值的极限。

基于离散算法的双包层Er^(3+)/Yb^(3+)共掺光纤激光器动态特性研究

采用基于速率方程的离散算法,对双包层Er3+/Yb3+共掺光纤激光器增益介质在不同位置的动态特性进行了分析。研究了增益介质在不同位置上的能级粒子数、激光功率随时间的变化。结果表明:增益介质在不同位置振荡达到稳态前上能级粒子数随时间的变化是不同的,并呈现出了不同的变化特点;不同位置处振荡开始时的最大峰值功率与达到稳态时的功率也不同;不同位置开始振荡的时间相同,达到稳态的时间也基本相同。对这一算法的稳态结果同简化速率方程的稳态分析值进行了对比,显示了泵浦功率较大且光纤长度较长时两者所具有的差异。

双包层Er^(3+)/Yb^(3+)共掺光纤激光器动态特性的分析

分析了弛豫振荡前上能级Er3+、Yb3+粒子数的变化和弛豫振荡时Er3+上能级粒子数的变化情况以及弛豫振荡时激光功率的变化规律 ,结果表明

Er-Yb共掺光纤光栅光纤激光器

提出了一种用两个完全相同的光纤光栅作谐振腔的Er-Yb共掺光纤激光器,并对其输出与温度特性进行实验研究,给出了Er-Yb共掺光纤的自发辐射谱及光纤光栅的透射谱,讨论了光纤光栅工作温度对激光器输出中心波长的影响。实验结果表明激光器的温度稳定性较好。

Er^(3+)-Yb^(3+)共掺DBR光纤激光器的实验研究

采用Er3+-Yb3+共掺单模光纤制作了DBR光纤激光器,有源光纤长度为10cm,光纤激光器为短腔结构。通过对不同前腔镜反射率的Er3+-Yb3+共掺DBR光纤激光器进行实验,得到了前腔镜反射率与激光器输出功率和阈值电流之间的关系,并对前腔镜反射率和有源光纤的长度的最优化选择进行了分析。

Er^3＋-Yb^3＋共掺杂光纤环型腔被动谐波锁模激光器

报道了Er3+-Yb3+共掺杂光纤作为增益介质的环型腔光纤激光器。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,通过调整泵浦功率,调节偏振控制器的状态,实现了连续基波锁模和高阶谐波锁模两种稳定的锁模运转状态。其中连续基波锁模重复频率15.89 MHz,中心波长为1.557 nm,光谱宽度为9.9 nm。二阶谐波锁模重复率为31.79 MHz,三阶谐波锁模脉冲重复率为46.99 MHz。观察到了调Q锁模和调Q脉冲序列,给出了各种运转状态的实验结果并对多种锁模机理作了简要的分析。

双包层Yb／Er共掺光纤激光器的特性研究

对980nm抽运的双包层Yb/Er共掺光纤激光器进行了数值模拟,分析了稳态情况下光纤中上能级粒子数,抽运光功率,信号光功率沿光纤轴向的分布。计算了激光器输出功率与光纤长度的关系,激光器输出腔镜反射率与输出功率的关系。根据数值模拟的结果,采用4m长的铒镱共掺双包层光纤作为增益介质,反射率为15%的双包层光纤光栅作输出腔镜组建了全光纤激光器,其斜率效率为40%。在3.4W的最大抽运功率下,得到了1.25W的激光输出,输出光谱宽度为0.49nm。

窄线宽36pm的Er∶Yb共掺硅基光纤激光器

实现了一个窄线宽36pm的Er∶Yb共掺硅基光纤激光器,输出中心波长是1 569.4nm.激光器的谐振腔是由一个高反的Bragg光纤光栅和另一端光纤端面4%的菲涅尔反射组成.用3.8m长的Er∶Yb共掺光纤,在975nm的LD激光器泵浦下,获得了最大输出功率达到6W,斜率效率达到23.5%,在输出功率范围内有明显的功率饱和现象.

光纤参数对双包层Er^(3+)/Yb^(3+)共掺光纤激光器的影响

为了研究掺杂浓度、包层尺寸对双包层Er3+/Yb3+共掺光纤激光器的影响,根据双包层Er3+/Yb3+共掺光纤激光器产生激光的机理,基于速率方程,采用改变Er3+,Yb3+掺杂浓度、内包层尺寸等光纤参数的方法,得到了双包层Er3+/Yb3+共掺光纤激光器随光纤参数变化的特征结果。结果表明,在Er3+掺杂浓度不变的情况下,增大Yb3+的掺杂浓度,可有效地提高激光器的输出功率;在Yb3+掺杂浓度保持不变的情况下,增大Er3+掺杂浓度,也可提高激光器的输出功率,但提高的幅度不明显;减小内包层尺寸,激光器的最佳光纤长度随之减小。

基于体布拉格光栅的高功率可调谐Er/Yb共掺光纤激光器

主要介绍基于体布拉格光栅(VBG)的宽调谐Er/Yb共掺光纤激光器.通过中心波长为976nm的半导体激光器(LD)包层泵浦Er/Yb共掺光纤,并利用VBG作为波长选择器件,在耦合进入光纤的泵浦光功率为51W的情况下,实现了13.1W的功率输出,激光中心波长为1570nm,相应的斜效率约26.6%.通过改变VBG的工作角度,实现了1532-1570nm连续可调谐激光输出,调谐范围达38nm,基本覆盖了整个光纤通信低损耗的C波段(1530-1565nm),激光功率输出水平≥10.66W.

双包层Er^(3+)／Yb^(3+)共掺光纤激光器粒子数空间分布特性研究

针对双包层光纤激光器内包层和纤芯中光强的不同分布,基于速率方程,研究了不同泵浦方式下双包层Er3+／Yb3+共掺光纤激光器上能级粒子数的空间分布。结果表明:无论采用何种泵浦方式,沿光纤的径向,越接近于纤芯中心处,上能级粒子数越低;越接近于纤芯边缘,上能级粒子数越高。沿光纤轴向,激光输出端归一化的上能级粒子数总是少于非输出端归一化的上能级粒子数。

大模场Er^(3+)/Yb^(3+)共掺锥形微结构光纤1.5μm激光特性

采用全矢量有限元法设计了一种大模场双包层微结构光纤及锥形波导结构。采用复丝拉制方法制备了成分为45Bi_(2)O_(3)-29GeO_(2)-15Ga_(2)O_(3)-10Na_(2)O-1CeO_(2)的大模场双包层微结构光纤,纤芯直径为70μm,内包层的占空比为0.25,模场面积约为3014.8μm^(2)。采用熔融拉锥技术制备了纤芯直径为17.5μm、有效模场面积为206.47μm^(2)的锥形光纤。在980 nm泵浦下研究了微结构光纤及其锥体的激光特性。结果表明,拉锥后微结构光纤的激发光谱中心波长由1550.2 nm向短波漂移至1546.9 nm,而输出激光光束质量因子M^(2)由3.45±0.03显著减少至1.16±0.01。拉锥前后的斜率效率分别达到10.29%和9.70%。研究结果表明,拉锥可有效改善大模场双包层有序微结构光纤的激光输出模式,拉锥后的激光输出具有良好的单模特性。该项技术研究结果为大模场、高功率的激光光纤材料制备提供了新的技术途径。

掺Er^(3+)/Yb^(3+)光纤激光的理论分析

提出了光纤腔掺Ｅｒ３＋／Ｙｂ３＋光纤激光的模型和速率方程，推导了阈值泵浦功率的解析公式．运用数值求解方法，得到了光纤中反转粒子数分布、小信号增益系数和激光的输出功率．同时也给出了数值曲线，可用于掺Ｅｒ３＋／Ｙｂ３＋光纤激光器的优化设计．

An all-fiber type Er^(3+)/Yb^(3+) co-doped fiber laser

In this paper, a distributed Bragg reflection (DBR) type Er3+/Yb3+ co-doped fiber laser of high output power and high slope efficiency was developed. Its gain medium was a 4.45-m-long Er3+/Yb3+ co-doped fiber. When it was pumped by a 1064-nm Nd:YAG, the linewidth of output laser was measured as 0.072 nm by 3 dB and 0.192 nm by 25 dB at 1552.08 nm. The maximum output power was measured as 69 mW. Its power stability was < 5%, side mode suppression ratio was 59 dB, and the output wavelength stability was +0.01 nm. The laser had a threshold of 12 mW and a slope efficiency of 22%.

Effect of power scale of 974 and 633 nm lasers on the induced loss at 633 nm of Yb3＋/Al3＋ co-doped silica fiber

Induced loss at 633 nm is tested in Yb3＋∕Al3＋co-doped silica fiber by a core pumped with a 974 nm laser and probed with a 633 nm laser. The fiber is prepared by the modified chemical vapor deposition method combined with solution doping. Different power scales of pump light and probe light are used in the tests. It is found that there is a dynamic equilibrium between photobleaching induced by 633 nm probe light and photodarkening（PD）induced by 974 nm pump light. For the first time to our knowledge, the effect of 633 nm probe laser power on an induced loss test of Yb3＋∕Al3＋co-doped silica fiber is studied quantitatively. It suggests that as long as the633 nm probe light power is less than 0.2 m W, the induced loss is mainly contributed by the PD effect of pumping light, and the deviation of induced loss is less than 5%.

1532nm全光纤Er/Yb共掺杂激光器

近年来,相干探测激光雷达是测量远距离低空风切变的有效手段,1.6μm波段固体激光器以其人眼安全、探测器件成熟等优势成为相干雷达主要光源。其增益介质Er:YAG晶体在1532nm波段有较强的吸收峰,但吸收谱较窄,因此通过使用1532nm光纤激光器进行谐振泵浦可以有效提高晶体输出效率。为此,文中以Er/Yb双包层光纤为增益介质,1532nm光纤光栅为反射腔镜,976nm半导体激光器为泵浦源,实现了全光纤化1532nm激光输出。输出激光最大功率73.44 W,波长可调谐范围为1531.35~1532.14nm,波长谱宽为0.06 nm,x和y方向的光束质量M2分别为1.38和1.26,是1.6μm固体激光器的理想泵浦源。并采用此激光器泵浦Er:YAG非平面环形腔获得1.3W单频激光输出,斜率效率为31.76%。

Optimal design of Er/Yb co-doped fiber amplifiers with an Yb-band fiber Bragg grating

In this paper, Er/Yb co-doped fiber amplifiers(EYDFAs) with an Yb-band fiber Bragg grating(FBG) at the pump end to improve the performance of the amplifier is systematically studied. The influence of the reflectivity and center wavelength of the FBG along with the gain-fiber length on the performance of an EYDFA are numerically analyzed. The results show that the wavelength of the FBG has critical influence on the efficiency of the EYDFA,whereas the requirement to its reflectivity is relaxed. It is an effective and promising way to improve the efficiency of a high-power pumped EYDFA by introducing a suitable Yb-band FBG at the pump end. Based on the analysis of the underlying principles, suggestions for the practical design and possible further improvement strategies are also proposed.