100 W级全光纤化线偏振单频光纤放大器

报道了一种基于主振荡功率放大结构的全光纤化1064 mm线偏振单频光纤放大器。种子源是一个线宽约为3 kHz的单频光纤激光器。输出功率为50 mW的种子激光经两级掺Yb保偏双包层光纤(光纤纤芯直径分别为10 μm和20 μm)和一级手性耦合纤芯增益光纤放大后,最终获得了输出功率138 W、光束质量M2≤1.2、偏振消光比优于18 dB的高功率单频光纤激光输出。在脉冲调制模式下,获得了峰值功率465 W、脉宽宽度约为500 μs的线偏振单频光纤激光输出。     

128 W单频线偏振光纤放大器特性研究

高功率单频激光在激光雷达、光谱学、精密测量等领域具有广阔的应用前景.采用中心波长为1064 nm、光谱线宽为20 kHz、偏振消光比（PER）高于20 dB的单频线偏振分布式反馈光纤激光器做种子源（尾纤输出功率约为10 mW）,利用种子注入主振荡功率光纤放大技术,通过两级级联放大实现了128 W高功率单频、线偏振、近衍射极限单模连续激光输出.主放大器光-光效率达到83%,PER高于12 dB.采用分段温控技术有效地提高了光纤中的受激布里渊散射（SBS）阈值,实验中未观察到明显的放大自发辐射和SBS现象,进 关键词： 掺Yb光纤放大器 主振荡功率光纤放大 单频 线偏振     

2 μm波段宽带可调谐全光纤激光器

设计并实验研究了一种采用Fabry-Perot (F-P)光纤滤波器的2 μm波段宽带可调谐全光纤环形激光器,经过放大的1 550 nm半导体激光泵浦单模铥-钬共掺光纤(THDF)获得2 μm波段宽带增益。实验结果表明,该结构在2 μm波段获得了195 nm调谐范围的激光输出,线宽0.05 nm,边模抑制比66.98 dB。整个结构采用铥-钬共掺光纤放大结构,可使输出功率达到瓦级。     

变纤芯直径传能光纤中受激拉曼散射传输特性的理论研究

锥形光纤纤芯直径沿着光纤长度方向均匀增大,在抑制非线性效应方面有着独特的优势。理论对比了单横模高斯光束输入时,输入纤芯直径均为50 μm、纤芯直径沿着光纤长度方向恒定、线性增大和非线性增大的变纤芯直径传能光纤的输出光谱演化和拉曼光特性。在相同条件下,输入功率10 kW时,恒定型传能光纤的输出光谱中,拉曼抑制比（定义为输出光谱中信号光峰值强度分贝值与拉曼光峰值强度分贝值之差）为33.1 dB,线性增大和非线性增大型的输出拉曼抑制比分别为47.0,48.6 dB,分别优于恒定型传能光纤13.9,15.5 dB;输入功率达17.5 kW时,恒定型传能光纤中有81.6%的输入能量被耗散或转移到其他波长,线性增大和非线性增大型仅不到2%,其输出的信号光波段能量占总输入能量的98.1%,98.9%。结果表明,使用线性增大型或非线性增大型传能光纤代替恒定型常规光纤,可以有效提高受激拉曼散射阈值,相关研究可以为大功率光纤合束器和光纤端帽的设计提供有益参考。     

All-fiber Tm-doped double-clad fiber laser with multi-mode FBG as cavity

An all-fiber LD-clad-pumped Tm-doped fiber laser was reported, and the CW maximal output power reached 24 W at nearly 1.94 μm. The double-clad Tm-doped fiber had a demission of 25/250 μm with the core NA 0.1 and inner-clad NA 0.46. A matched passive multi-mode FBG acted as the front cavity. Cooling by the water, the 56% high slope efficiency was achieved and threshold was 6.4 W, respected to the launched pump power. At the low power pump, the fiber laser spectrum had only one peak at 1.936 μm. Increasing the launched pump power, the output laser wavelength grew to 3–4 peaks. Because the multi-mode FBG reflectivity was not very high, both ends of the fiber laser had laser output power, and the ratio was nearly 10:1.     

楔形光纤与半导体多量子阱平面光波光路芯片的耦合分析

采用楔形光纤(WSF)实现了与半导体多量子阱(MQW)平面光波光路(PLC)芯片的高效耦合。在多量子阱-平面光波光路前置模斑转换器(SSC)和不加模斑转换器的情况下,用阶梯串联法(SCM)数值模拟并优化设计了楔形光纤-平面光波光路间最佳耦合参量:楔形光纤楔角45°、端面圆柱透镜曲率半径2.5μm、模斑转换器-多量子阱-平面光波光路出射椭圆光斑长半轴3.5μm、纵横比5、楔形光纤-平面光波光路间垂直方向和水平方向无偏移、纵向间距5.5μm。用反向推演法(IDM)实验分析了楔形光纤样品的出射光场,与阶梯串联法(SCM)计算结果相比长轴误差为3.125%,短轴误差为0.8%。建立楔形光纤-平面光波光路-单模光纤(SMF)的耦合实验系统,在1.55μm波长处以单模光纤作为出纤的相同条件下,发现楔形光纤激励入射平面光波光路比单模光纤和锥形透镜光纤(TLF)作为入纤的耦合效率分别提高了24.827 dB和16.22 dB,为多量子阱-平面光波光路芯片尾纤封装技术提供了实验原型。     

基于简单MOPA结构实现3.08 kW全光纤窄线宽线偏振激光输出

基于简单的主振荡功率放大结构,演示了一种高功率窄线宽线性偏振全光纤激光器,其最大输出功率为3.08 kW,3 dB线宽为0.2 nm。在整个功率缩放过程中,偏振消光比约为94%,光束质量M 2约为1.4。这是国内外首次实现3 kW全保偏光纤激光输出,与基于相位调制的窄线宽激光器相比,该激光器可实现近似的线宽,同时具有受激布里渊散射阈值高、系统结构简单、成本低等特点。     

国产掺镱双包层光纤的激光特性

 采用MCVD方法研发了掺镱双包层光纤，并对其结构特性、荧光特性和激光特性进行了测试和研究。其D形内包层尺寸为400/450μm，数值孔径为0.36,纤芯直径约为16μm，数值孔径约为0.18。荧光谱线的范围为1 000~1 140 nm，1 030 nm处的峰宽大于50 nm。采用大功率激光二极管单端泵浦6 m长的双包层光纤，在泵浦入纤功率为61 W时， 获得了32 W的激光输出，斜率效率为64%。该光纤在高功率处未发现饱和现象，通过优化光纤参数与泵浦方式还可以提高转化效率和输出功率。实验表明该光纤可以取代进口光纤用作高功率激光器件。     

Fiber-coupled diode end-pumped Q-switched Tm,Ho:YLiF4 laser

At liquid-nitrogen temperature, at 10-kHz pulse repetition rate, Q-switched 36-ns pulses with average output power of 4 W at 2.05 μm and 4.5-W continuous wave output power with a total optical-optical conversion efficiency of 30%, were achieved from a 6% Tm, 0.5% Ho:YLiF4 laser. This laser was endpumped by a fiber-coupled laser diode emitting up to 15 W around 792 nm. The 1-m-long optical fiber carrying the pump radiation has a core diameter of 700 μm with a numerical aperture of 0.22.     

Linearly polarized intracavity passive Q-switched Yb-doped photonic crystal fibre laser

In this paper we report linearly polarized high average power passive Q-switched ytterbium-doped photonic crystal fibre laser with a Cr⁴⁺:YAG crystal as a saturable absorber. An average output power of 9.4 W with pulse duration of 64 ns and pulse repetition rate of 57.4 kHz with a slope efficiency of 52% was achieved. Measured polarization extinction ratio (PER) of the Q-switched laser output was 10.5 dB.     

A 0．98μm Laser Diode Pumped Erbium－Doped Fiber Amplifier with 40nm Bandwidth

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1.5kW全光纤线偏振激光器

报道了一台全光纤结构的1.5kW线偏振光纤激光器。激光器采用振荡器结合一级放大的主振荡功率放大器(MOPA)方案。振荡器中心波长为1080nm,工作时输出功率30 W,经放大器一级放大后实现近衍射极限输出,功率达到1.5kW,光-光效率81.5%,消光比13.8dB。这是目前线偏振光纤激光器输出功率的最高值。     

LD-clad-pumped nanosecond Tm<Superscript>3+</Superscript> doped silica fiber amplifier at 1.99 μm

ALD-clad-pumped nanosecond Tm³⁺ doped silica fiber amplifier was reported that provided up to a 2-W average power output with a slope efficiency of 48.6% with respect to the absorbed pumped power. The input signal central wavelength was at 1.99 μm, with a 119.5-ns pulse duration and 5-kHz repeat rates. The pump sources were a 793-nm LD output with a 400-μm pigtail fiber. The gain fiber was D-shaped Tm³⁺ doped silica double-clad fiber with a diameter of 27.5/400 μm. The output amplified pulse and spectrum were in accordance with the input signal. This is the first report to the authors’ knowledge on the general experimental investigation of a LD-clad-pumped Tm³⁺ doped silica nanosecond-fiber amplifier at 1.99 μm.     

Er-doped photonic crystal fiber amplifier with 70 W of output power

We report for the first time, to the best of our knowledge, on a large mode area Er-doped photonic crystal fiber laser system. The fiber core had a diameter of 40 μm and NA of <0.04 leading to a mode field diameter of about 31 μm around 1550 nm wavelength. More than 70 W of single-frequency output power at 1556 nm could be extracted using a master-oscillator power-amplifier scheme. Near diffraction limited output beam quality has been verified by measuring the TEM(00) content with a nonconfocal scanning ring cavity.     

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

In this paper, a distributed Bragg reflection (DBR) type Er~(3+)/Yb~(3+) 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%.     

Performance of data link modules as a function of multimode fiber size

Commercial data link modules from three manufacturers were measured for transmitter launch power and receiver sensitivity when used with the five common graded-index multimode fiber types: 50 μm core/NA_mk, = 0.20; 50 μm/NA_m = 0.23; 62.5/0.275; 85/0.26: and 100/0.29. Depending on the model, transmitters launched from 2.8 to 4.4 dB more power into the 100 pm fiber than the 62.5 μm fiber, whereas receiver sensitivities decreased by up to 3.5 dB. These variations in launch power and receiver sensitivity complicate the selection of an ideal fiber and emphasize the need for specifying data link performance with the particular fiber of interest. In general, the system gain of typical transmitter/receiver pairs is less favorable to large diameter fibers than previously believed.     

Fiber Optic Coupling of CW Linear Laser Diode Array

Based on a set of microoptics the output radiation from a continuous wave (CW) linear laser diode array is coupled into a multi-mode optical fiber of 400 μm diameter.The CW linear laser diode array is a 1 cm laser diode bar with 19 stripes with 100 μm aperture spaced on 500 μm centers.The coupling system contains packaged laser diode bar,fast axis collimator,slow axis collimation array,beam transformation system and focusing system.The high brightness,high power density and single fiber output of a laser diode bar is achieved.The coupling efficiency is 65% and the power density is up to 1.03×104 W/cm2.     

少模光纤放大器中的准静态模式不稳定实验研究

模式不稳定发现于2010年,是影响高功率光纤激光器功率提升的重要限制因素.当前模式不稳定主要有两类,一类是动态模式不稳定,一类是准静态模式不稳定.本文研究了纤芯/内包层直径为25μm/400μm掺镱双包层光纤后向抽运放大器中的模式不稳定效应.通过对功率、光束质量和时域数据的分析,发现在该放大器中出现了准静态模式不稳定的现象,随着抽运功率的增加,放大器输出光束质量逐步退化,而时域上没有发现明显的动态模式不稳定特性.实验上对不同种子功率下放大器的输出特性进行研究,结果表明,通过提高种子激光功率可以较为有效地提高模式不稳定阈值,在种子功率为528 W时,当输出功率大于3000 W,输出激光效率没有明显下降.     

Fiber Optic Coupling of CW Linear Laser Diode Array

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飞秒光脉冲光纤放大增益特性的实验研究

报道了掺Ｅｒ＾３＋光纤激光器输出１．５３１μｍ波长飞秒激光脉冲增益放大的实验研究结果,将自起振相加脉冲摹参Ｅｒ＾３＋光纤激光器输出的飞秒激光脉冲注入掺Ｅｒ＾３＋光纤放大器中进行放大,分别采用正向和逆向抽地这的方式,得到了最高放大倍数５５倍（１７．４ｄＢ）和６４倍（１８．１ｄＢ）的增益,对应的最大单脉冲能量（峰值功率）分别为０．３８４ｎＪ（７５２Ｗ）０．４５２ｎＪ（１２９５Ｗ）,脉冲重复率为２０．８