多泵浦与光纤级联结合的宽带拉曼光纤放大器

针对传统光纤通信传输系统中拉曼光纤放大器(RFA)增益带宽不足、输出增益低且输出增益不平坦的问题,设计了一种多泵浦和光纤级联相结合的宽带拉曼光纤放大器。并且推导实现增益平坦输出时所用六个泵浦光和四段光子晶体光纤(PCF)对应参数满足的约束表达式,从理论上给出了一种提高放大器增益和增益带宽的同时保证较小增益平坦度的设计方法。最后通过Matlab数值模拟,所设计的宽带拉曼光纤放大器达到了增益带宽92 nm,平均增益39.95 dB,增益平坦度0.1447 dB。     

多泵浦增益平坦光子晶体拉曼光纤放大器

针对密集波分复用光纤通信系统中拉曼光纤放大器增益及增益谱平坦问题,提出一种采用4个泵浦光的多泵浦方式在光子晶体光纤不同位置处注入两种不同波长泵浦光的组合方式来获得拉曼光纤放大器增益更大、增益谱更加平坦的方法。这种组合方式在拉曼光纤放大器中使得光信号实现了前段放大、后段补偿,从而在拉曼光纤放大器输出端获得高增益和较平坦增益谱。模拟的结果表明:平均增益可达:26.5 dB,增益平坦度为0.046 dB。     

Ultra-wide-band tellurite-based fiber Raman amplifier

We describe the first wide-band tellurite-based fiber Raman amplifier (T-FRA) for application to seamless ultra-large-capacity dense wavelength-division multiplexing (WDM) systems. First, we confirmed that the Raman scattering characteristics of the tellurite-based fiber has so large a gain coefficient and Stokes shift that we can achieve a wide-band tellurite-based fiber Raman amplifier with a shorter fiber length than when using silica-based fiber. Second, we investigated the small signal gain and the signal transmission characteristics for a high gain and high output power operation with a single-stage amplifier. Focusing on double Rayleigh scattering, we compared the high gain limit of tellurite- and silica-based fibers. We then studied the impact of nonlinear effects by measuring the bit error rate (BER) when using a two-stage amplifier with a high output power of 18.8 dBm in which we simultaneously amplified eight channel signals in the L-band located on the ITU 100-GHz grid. Finally, we designed a wide-band tellurite-based fiber Raman amplifier with a multiwavelength band pumping scheme. We constructed this amplifier with a tellurite-based fiber only 250 m in length pumped by four-wavelength-channel laser diodes, and it provided a 160-nm bandwidth with a gain of over 10 dB and a noise figure below 10 dB from 1490 to 1650 nm. We also measured the BER to confirm the transmission characteristics of the amplifier for single channel operation over the whole signal wavelength range of 160 nm. We thus confirmed that the amplifier could be employed in ultra-high-capacity WDM systems.     

Thulium-doped tellurite fiber amplifier

Gain in the S-band is demonstrated in a thulium-doped tellurite fiber amplifier using dual pump and bidirectional pumping schemes. Two pump schemes were employed: 795/1064 and 1047/1550 nm. The gain profile is broader than achieved in a fluoride fiber and overlaps with the C-band of the erbium-doped fiber amplifier. We reach a fiber-to-fiber gain of 11 dB and an internal gain of 35 dB.     

Prediction of gain peak wavelength for Er-doped fiber amplifiersand amplifier chains

We present a simple rule for predicting the gain peak wavelength (GPW) of an Er-doped fiber amplifier. For a given fiber type, the GPW is determined solely by the operating gain per unit length. Using this rule coupled with a simple Er-doped fiber amplifier model and measured modeling parameters, the GPW is predicted for a particular Er-doped fiber. The result is verified by direct measurement in a fiberloop. We demonstrate that the gain peak does not vary with pump power, pump wavelength or signal power as long as the gain per unit fiber length is fixed. Extension of this theory to include the wavelength dependences of other components in an amplifier chain is also discussed and demonstrated     

基于粒子群优化算法的级联喇曼光纤放大器

为了在较高的净增益条件下实现最小化喇曼增益平坦度,采用粒子群优化算法对As-S光纤与碲基光纤级联的光纤放大器各抽运光参量优化配置的方法,进行了理论分析和实验验证。结果表明,应用上述方法对得到的3组优化结果进行对比,在带宽为40nm的级联喇曼光纤放大器上,达到了平均增益为53.25dB、增益平坦度为0.30dB的较高性能。与传统光纤放大器和现有的级联光纤放大器相比,使用粒子群优化算法对各抽运光的功率和波长优化后,会使级联光纤放大器性能明显提高,这在未来的光纤通信中具有一定实用价值。     

Suppression of stimulated Brillouin scattering in high-power single-frequency multicore fiber amplifiers

To describe the interplay between the first-order Stokes, pump, and signal in the multicore fiber amplifier, a set of differential equations is presented. The model takes into account the dependence of the stimulated Brillouin scattering (SBS) on the pump-induced temperature distribution along the fiber. The influence of pump schemes, pump powers, convective coefficient, density of the rare earth dopant (N) and fiber length on suppression of the SBS is studied. The backward pump scheme has advantage over forward pump scheme in suppression of SBS. For the SBS gain spectrum, reducing convective coefficient can decrease the maximum SBS gain and increase the frequency detuning corresponding to the maximum SBS gain. Increasing N can lead to higher slope efficiency and shorter optimal fiber length, which can further suppress SBS. The SBS gain (G) and maximum operating temperature are compared between the single core fiber amplifier and multicore fiber amplifier with the same optimal fiber length. Compared to the single core fiber amplifier, the multicore fiber amplifier has lower maximum operating temperatures, which provide more space for further increasing output power.     

前途光明的宽带混合光纤放大器

由掺铒光纤放大器（EDFA）和光纤嗽曼放大器（FRA）构成的宽带混合光纤放大器（Wideband Hybrid Fiber Amplidfier)具有高增益,宽带宽,低噪声,高输出功率等优点,是今后光纤放大器的发展方向,本文概括院落带混合光纤放大器的典型结构。综合报道了近年来的研究进展和最新发展动态,最后展望了这种混合放大器的应用前景。     

Passive gain-equalized wide-band erbium-doped fiber amplifier using samarium-doped fiber

A passive gain-equalization technique of erbium-doped fiber amplifier (EDFA) using a samarium-doped fiber to obtain wide-band flattened gain operation is reported. In the wavelength range from 1529-1559-nm, small inter-channel gain variations can be achieved. This simple technique is suitable for multiwavelength wide-band in-line-amplifier cascaded transmission applications.     

光纤长度优化的高功率铒镱共掺光纤放大器

为了研究不同增益光纤长度下1555nm高功率光纤放大器的输出功率,采用两级混合结构的方法,用掺铒光纤放大器和双包层铒镱共掺光纤放大器分别作为1级预放大器和2级主放大器。掺铒光纤放大器对信号光进行预放大,并提高放大器的信噪比;双包层铒镱共掺光纤放大器为主放大器,其双包层结构可以把更多的多模抽运光耦合进系统。对铒镱共掺光纤的最佳长度做了理论分析和实验验证,在信号光功率为10mW、掺铒光纤放大器的抽运功率为318.58mW、双包层铒镱共掺光纤放大器的抽运功率为11.71W、增益光纤长度为14m时,输出功率取得了2.11W的实验数据。在分析输出信号光谱时发现,L波段附近有放大自发辐射谱出现,这是选择的增益光纤过长导致的。结果表明,在光功率和信号光功率一定时,光纤放大器有一个最佳的光纤长度。这一结果对研究光纤放大器的高功率输出是有帮助的。     

光纤参量放大器技术及其最新进展

介绍和论述了一种非常有实用前景的基于光纤非线性效应的光参量放大器(OPA)及其最新技术进展．最新发展揭示了它的很多技术特性优于传统的掺铒光纤放大器(EDFA)、半导体光放大器(SOA)和近年来很热门的光纤拉曼放大器(FRA)，如对信号的调制形式、比特率的完全透明性、相位共轭、超宽的增益带宽、很低的噪声指数和具备优异的全光波长转换功能．     

面向6G的拉曼微结构光纤放大器设计

为了满足6G系统对未来光通信网络的要求,利用掺 GeO₂微结构光纤设计了一种多泵浦拉曼光纤放大器,该方案能够解决适用于6G系统需求的 拉曼光纤放大器中谱宽窄、输出增益低且不平坦的问题。在理论上,运用四阶龙格-库塔法 对经典拉曼耦合波微分方程进行求解;在结构上,通过合并两对具有相同波长的泵浦光,来 减少泵浦个数、简化结构,同时采用级联两段微结构光纤的方法,使信号光增益在拉曼放大 器的输出端实现前放大,后补偿。实验结果表明,在100 nm的谱宽范 围内,放大器的平均增益高达35.72 dB,增益波动小于±0. 43 dB。     

200-nm-bandwidth fiber optical amplifier combining parametric andRaman gain

Theory shows that the gain bandwidth of a one-pump fiber optical parametric amplifier (OPA) using highly nonlinear fiber (HNLF) could be more than 200 nm. Under these circumstances, the OPA gain would overlap the pump-induced Raman gain. We have studied the combined effects of OPA and Raman gain theoretically and experimentally. The experimental results demonstrate a 200-nm bandwidth from a single fiber-optical amplifier and also verify that the influence of the Raman effect is relatively small, as predicted by the theory     

Erbium-doped fiber amplifier with flattened gain spectrum

An optical notch filter was incorporated within the length of all erbium-doped fiber amplifier. Careful choice of the filter characteristics and location made it possible to enhance the amplifier gain at wavelengths around 1550 nm. An amplifier with 27-dB gain and 33-nm bandwidth was demonstrated. The saturation characteristics of the amplifier were uniform across its gain spectrum, making it ideal for wavelength division multiplexed (WDM) application.<>     

基于铒镱共掺光纤放大器的仿真研究

基于铒镱掺杂光纤放大器具有光纤短增益特性好的优点,对在混合光纤放大器中用铒镱掺杂光纤放大器来代替掺铒光纤放大器的方法进行了研究,并对铒镱光纤的长度和掺杂浓度进行了精心的选择,而后利用仿真软件对在2.5Gb/s和10Gb/s速率下的混合光纤放大的DWDM系统进行了仿真分析.     

Second-order harmonic distortion and optimal fiber length in erbium-doped fiber amplifiers

The gain of an erbium-doped fiber amplifier (EDFA) operating in the kHz regimes and its second-order harmonic distortion (SBD) are studied. Using the rate and beam-propagation equations, we have shown the dependences of the distortion on the pump power, the modulation frequency, and the position along the fiber. Moreover, it is found that the SHD is the smallest when the fiber has an optimal length for the maximum gain. A relation between the optimal length and fiber parameters is presented for calculating easily the optimal fiber length in an EDFA.     

基于改进粒子群算法的后向泵浦RFA设计北大核心CSCD

为了满足第六代移动通信(6G)系统对光通信网络的高速率及大容量的要求,进一步提高光传输网络中光纤放大器的带宽、响应速率及放大倍数等成为目前的研究重点。在使用碲酸盐光纤作为光纤增益介质的同时,提出一种改进粒子群优化算法,通过在迭代过程中动态的调整速度、位置及惯性权重值,获得更高收敛速度,增强全局搜索的能力。应用该算法对拉曼光纤放大器的各个泵浦光参数配置进行优化、分析及仿真验证,最终设计出平均开关增益为23.738 8 dB,增益平坦度为0.209 8 dB的后向泵浦拉曼光纤放大器。结果表明,改进的粒子群优化算法对拉曼放大器泵浦光的参数配置有很强的适应性,能够获得较低的增益平坦度,对未来拉曼光纤放大器的设计具有一定的参考意义。     

正向抽运喇曼光纤放大器开关增益数值计算研究

采用数值计算的方法,对影响正向抽运喇曼光纤放大器(RFA)开关增益的几个因素——喇曼增益系数、抽运光功率、光纤长度、光纤损耗、有效纤芯面积等参数与正向抽运喇曼光纤放大器开关增益的关系进行了分析研究,并把数值分析的结果和小信号的解析结果进行了比较,然后在此基础上提出了有效提高正向抽运喇曼光纤放大器开关增益的几种方法。     

Segmented-clad fiber design for tunable leakage loss

This paper proposes a novel segmented-clad fiber (SCF) design in which the spectral variation of leakage loss of the fundamental mode can be finely tuned by varying the fiber parameters. A fiber with such optimized spectral variation of leakage loss should find application in the realization of inherently gain-flattened optical fiber amplifiers, wavelength filters, wavelength-flattened attenuators, etc. In this paper, the authors present SCF designs optimized for realizing inherently gain-flattened S-band erbium-doped fiber amplifier (EDFA) and high-gain discrete Raman fiber amplifier (RFA). Amplifier characteristics have been modeled in both cases, and simulations show that a 20-dB gain with /spl plusmn/0.9 dB of gain ripple over a 30-nm bandwidth in S-band is achievable with the designed EDFA based on the optimized SCF. In case of discrete RFA based on SCF, a 20-dB net gain with /spl plusmn/0.5-dB ripple is shown to be achievable over a 28-nm wavelength range in S-band.     

基于级联光纤环形镜的增益平坦掺铒光纤放大器

基于光纤环形镜的滤波原理,提出利用级联结构光纤环形镜(FLM)实现掺铒光纤放大器(EDFA)增益平坦滤波的方案,并进行了相关实验研究.实验结果显示,使用级联FLM取得了明显的增益平坦效果,其1535-1557nm波长范围内的增益不平坦度由±5dB减小到±1dB.