光纤拉曼放大器

主要讨论了光纤拉曼放大器的原理、历史、现状和前景，同时分析了它的设计原则、增益均衡的各种方法，给出了拉曼放大器的仿真模型。最后讨论了放大器基本特性对系统性能的影响。     

色散补偿型光纤拉曼放大器的增益和噪声指数的实验研究

对S波段的色散补偿型分布式光纤拉曼放大器(FRA)进行了研制。本放大器中采用了先进的光纤拉曼激光器作为抽运源,并对5km DCF-50km G652光纤色散补偿型分布式FRA分别进行了前向抽运和后向抽运,测量了其前向和后向增益光谱和噪声谱,结果表明后向抽运方式在增益和噪声特性方面优于前向抽运方式。对色散补偿型分布式FRA在后向抽运方式下的增益和噪声指数随抽运功率的变化而变化的规律进行了实验研究,结果表明其增益随抽运功率的增大而增大,噪声指数随增益的增大而减小。为比较色散补偿型分布式FRA和分布式FRA在增益和噪声方面的性能,分别测量了上述两种光纤拉曼放大器在后向抽运方式下的增益谱和噪声指数谱,结果表明：5km DCF-50km G652光纤制成的色散补偿型分布式FRA的增益和噪声特性,均优于由50km—G652光纤制成的分布式FRA。本文对实验结果进行了理论分析。     

光纤拉曼放大器及其在工程中的应用

近些年来，随着光通信技术的迅猛发展，特别是掺铒光放大器(EDFA)、光合／分波器、前向纠错(FEC)等技术在密集波分(DWDM)通信系统中的成功应用，以及光传输系统的速率由起初的155M、622M、2．5G，一跃达到了10G、40G、80G、200G，甚至达到了1．6T，系统的传输容量急增，显著增加了光纤中可传输的信息总量和传输距离。但是随着传输速率的提高，     

正在崛起的新型光纤放大器——拉曼光纤放大器

拉曼(Raman)光纤放大器(RFA)是被誉为光纤通信发展里程碑的掺饵光纤放大器(EDFA)之后又一个引人注目的光放大器。RFA的出现,将会对光纤放大器和光纤通信产生重大的影响。人们对RFA的兴趣来源于这种放大器可以提供整个光纤波长波段的放大,通过适当改变泵浦激光光波波长可达到在任意波段进行光放大的宽带放大器,甚至可以在1270nm～1670nm整个光纤波段内提供光放大。     

瑞利散射对拉曼光纤放大器性能的影响及抑制措施

瑞利散射是影响拉曼光纤放大器性能的重要因素。本文系统地分析了瑞利散射对拉曼光纤放大器噪声、串扰和功率代价等性能的影响，指出优化选择泵浦功率和泵浦方式以及插入光隔离器等措施可以降低瑞利散射的影响，从而为拉曼光纤放大器的优化设计提供了依据。     

拉曼光纤放大器的特性与前景

通过对拉曼光纤放大器（FRA）的研究和分析,揭示了FRA的有关特性。结合光纤通信的需求和FRA的特性分析了FRA的应用前景和潜在问题,并介绍了FRA的最新发展状况。     

光纤拉曼放大器噪声特性的研究

研究了拉曼放大器中的几种主要噪声,分析了噪声的来源及特点,给出了描述噪声的方程,并对其进行了数值计算,提出了改进噪声性能的方案。     

光纤中点缺陷对分布光纤拉曼放大器性能的影响

阐述了考虑传输光纤中存在点缺陷损耗和反射时背向抽运光纤拉曼放大器 (B DFRA)性能的分析方法 ,计算并分析了点缺陷对增益、放大的自发拉曼散射噪声和二次瑞利散射 (DRB)噪声的影响 ,还通过带B DFRA预放器的接收终端等价接收灵敏度讨论了点缺陷作用的综合效果。     

色散补偿型光纤拉曼放大器的增益和噪声指数的实验研究

对S波段的色散补偿型分布式光纤拉曼放大器(FRA)进行了研制。本放大器中采用了先进的光纤拉曼激光器作为抽运源,并对5 km DCF-50 km G652光纤色散补偿型分布式FRA分别进行了前向抽运和后向抽运,测量了其前向和后向增益光谱和噪声谱,结果表明后向抽运方式在增益和噪声特性方面优于前向抽运方式。对色散补偿型分布式FRA在后向抽运方式下的增益和噪声指数随抽运功率的变化而变化的规律进行了实验研究,结果表明其增益随抽运功率的增大而增大,噪声指数随增益的增大而减小。为比较色散补偿型分布式FRA和分布式FRA在增益和噪声方面的性能,分别测量了上述两种光纤拉曼放大器在后向抽运方式下的增益谱和噪声指数谱,结果表明: 5 km DCF-50 km G652光纤制成的色散补偿型分布式FRA的增益和噪声特性,均优于由50km-G652光纤制成的分布式FRA。本文对实验结果进行了理论分析。     

光纤拉曼散射效应及其应用研究

测量了G652光纤和DCF光纤的背向散射光谱，在斯托克斯区观察到一级和二级拉曼背向散射光谱，在反斯托克区观察到一级拉曼背向散射光谱，首次在斯托克斯区和反斯托克区观察到ZX背向散光谱。光纤背向散射效率直接应用于光纤拉曼放大器和分布式光纤拉曼温度传感器系统。讨论了分布式光纤拉曼温度传感器系统工作原理、结构，给出了实验结果。     

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.     

Raman amplifier model in single-mode optical fiber

Equations to describe the process of Raman amplification in single-mode optical fiber and Stokes and anti-Stokes spontaneous emission generation with conservation of photon number are derived from first principles. The numerical simulation of Stokes and anti-Stokes spontaneous emission is in good agreement with experimental results. The importance of the sometimes-omitted anti-Stokes spontaneous emission terms in wavelength-division-multiplexed situations for optical signal-to-noise ratio is demonstrated by the simulation of light propagation through transmission fiber with and without Raman amplification.     

Amplified spontaneous Raman scattering in fiber Raman amplifiers

Amplified spontaneous Raman scattered light power in forward and backward Raman amplifiers is theoretically and experimentally studied under the assumption of the constant Raman gain coefficient in the bandwidth of an optical filter. On the basis of the results, the power ratio of the amplified signal to amplified spontaneous scattering is discussed. As a result, it is clarified that the effect of amplified spontaneous Raman scattering on the signal to noise ratio for backward Raman scattering is larger than for forward Raman scattering.     

Raman fiber oscillator as optical amplifier

A Raman fiber oscillator used for optical amplification is demonstrated to have lower double Rayleigh scattering, transient spikes, cross-phase modulation, and higher saturation input threshold compared with a conventional discrete Raman amplifier at similar operating conditions. This could be a promising technology for deployment in practical systems.     

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。     

Effect of a nonlinear photonic Crystal fiber on the noise characterization of a distributed Raman amplifier

The first experimental study of the effect of a nonlinear photonic crystal fiber (PCF) on the noise characteristics of a distributed backward-pumped Raman amplifier is reported. The PCF has a highly nonlinear Raman efficient, and a high Rayleigh scattering parameter. When an optical signal first passes through a 100-m nonlinear PCF followed by a 25-km single-mode fiber, the optical signal-to-noise ratios (OSNRs) of the amplified spontaneous emission and the double Rayleigh scattering (DRS) are improved because the high Raman gain efficiency of the PCF makes the Raman gain of the signal at the beginning of the link increase, and the signal power over the length of the transmission becomes near a constant. However, the improvement of the OSNR of DRS compared with the OSNR of amplifier spontaneous emission is limited by the large Rayleigh scattering in the PCF.     

前向多泵浦拉曼放大器中噪声的精确分析

ASE噪声和DRBS噪声是影响拉曼光纤放大器传输性能的两个重要因素。本文运用四阶龙格-库塔法对多泵浦RFA的噪声功率进行仿真,进一步得到ASE和DRBS噪声的信噪比和噪声系数。结果表明,当光纤长度L<30 km时,ASE噪声对系统影响较大,而L>40 km时,DRBS噪声是影响系统性能的主要因素。另外,长波长的噪声比短波长信道的噪声功率更高,对系统的影响更大。当信号光波长相差24 nm时,长波长的ASE噪声饱和值至少比短波长高0.005 mW,DRBS噪声饱和值至少比短波长高0.0025 mW。     

混合链路光纤喇曼放大器研究

对由普通单模光纤 (SMF) ,色散补偿光纤 (DCF)作为喇曼增益介质的两种结构的混合链路光纤喇曼放大器进行了实验研究 ,并对实验情况下的实际传输系统中的混合喇曼放大链路进行了理论数值模拟 ,比较和分析了两种链路结构的增益和噪声特性     

OptiAmplifier下的光纤拉曼放大器仿真探究

本文利用Optiamplifier光放大器设计软件对拉曼放大器的泵浦光源种类、泵浦光源波长、泵源数目及功率的大小,及采用何种光纤等方面进行了仿真实验,最后从成本、实用角度出发采用三泵源实现了1530~1600nm放大带宽、平坦增益等性能指标。