Ultra-long-span 500 km 16/spl times/10 Gbit/s WDM unrepeatered transmission using RZ-DPSK format

Ultra-long-span 500 km 16/spl times/10 Gbit/s WDM unrepeatered transmission without dedicated fibre for remote pumping is successfully demonstrated for the first time. Enabling technologies are the RZ-DPSK format, forward pumped Raman amplification, and second-order backward pumped Raman amplification in combination with enlarged effective area SMF and conventional SMF.     

Design of Hybrid Optical Amplifiers for High Capacity Optical Transmission

This paper describes our design of a hybrid amplifier composed of a distributed Raman amplifier and erbium‐doped fiber amplifiers for C‐ and L‐bands. We characterize the distributed Raman amplifier by numerical simulation based on the experimentally measured Raman gain coefficient of an ordinary single mode fiber transmission line. In single channel amplification, the crosstalk caused by double Rayleigh scattering was independent of signal input power and simply given as a function of the Raman gain. The double Rayleigh scattering induced power penalty was less than 0.1 dB after 1000 km if the on‐off Raman gain was below 21 dB. For multiple channel amplification, using commercially available pump laser diodes and fiber components, we determined and optimized the conditions of three‐wavelength Raman pumping for an amplification bandwidth of 32 nm for C‐band and 34 nm for L‐band. After analyzing the conventional erbium‐doped fiber amplifier analysis in C‐band, we estimated the performance of the hybrid amplifier for long haul optical transmission. Compared with erbium‐doped fiber amplifiers, the optical signal‐to‐noise ratio was calculated to be higher by more than 3 dB in the optical link using the designed hybrid amplifier.     

Bidirectional optical fiber transmission systems using Ramanamplification

Bidirectional optical fiber transmission systems using Raman amplification are discussed. Analytical expressions for signals amplified by both forward and backward Raman scattering are presented. It is found that there exists an optimal pump power for the maximum unrepeated transmission length in a bidirectional system and that the maximum length is about 450 km, which is about the same as that of the unidirectional system     

基于高斯拟合的级联光子晶体光纤拉曼放大器

为了满足超高速、大容量的光纤传输系统的需求,本文在两段光纤级联结构的基础上,分析了光子晶体光纤的拉曼增益谱并采用高斯曲线对其进行拟合,设计了一种高增益、宽带宽的拉曼光纤放大器。高斯曲线拟合完整准确地保留了光子晶体光纤的增益谱信息,同时尽可能地增加了信号的传输带宽。利用四阶龙格-库塔法对经典的拉曼耦合波微分方程进行数值求解,不仅降低了放大器的增益平坦度,也实现了高增益放大。相比于直线拟合光纤拉曼增益谱的方法,提升了系统的传输容量。通过仿真分析得到:放大器的放大带宽为61 nm,其增益高达22.8 dB,增益平坦度仅为0.42 dB。     

Field demonstration of distributed Raman amplification with 3.8-dBQ-improvement for 5×120-km transmission

The benefits of distributed Raman amplification are demonstrated in a buried cabled field fiber. The performance improvement of 3.8 dB was achieved in a 5×120-km 10-Gb/s transmission experiment using 650-mW Raman amplification in each span without apparent damage to the fiber plant. The field results are compared to a similar laboratory experiment using a fusion-spliced fiber to evaluate the effect of finite optical reflections from nonfusion splices in the field fiber     

基于扫描激光器和光放大的100 km光纤布拉格光栅传感系统

提出了对基于扫描激光器的光纤布拉格光栅(FBG)传感系统进行掺铒光纤(EDF)/双波拉曼混合放大的方法,大幅度提高了该光纤布拉格光栅传感系统的传输距离。该方法以高功率扫描激光器作为光源,采用双波长拉曼放大的方法对信号进行低噪声双向放大,再利用系统中间的两段掺铒光纤,将剩余的拉曼抽运功率用来产生自发辐射光和放大传感信号,使得整个系统能在超长的传感距离上获得良好的信噪比(SNR)。实验表明使用一台扫描激光传感分析仪、一只170mW的拉曼抽运和一只2W的拉曼抽运,可以使传感距离达到100km以上,并且传感系统的光纤布拉格光栅反射信号均能获得超过7dB的良好信噪比,从而实现在超长距离上的光纤布拉格光栅传感。     

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.     

Raman amplification for fiber communications systems

Raman amplification has enabled dramatic increases in the reach and capacity of lightwave systems. This tutorial explains why, starting with the fundamental properties of gain from stimulated Raman scattering. Next, noise accumulation from amplified spontaneous emission is reviewed, and the merits of distributing Raman gain along a transmission fiber are explained. Other sources of noise that are particularly relevant for Raman amplifiers are summarized. Finally, novel Raman pumping schemes that have recently been developed are highlighted.     

Experiments on long-haul broadband WDM transmission with Ramanamplification

It is experimentally confirmed that Raman amplification with multi-wavelength pumping sources enables the pass bandwidth to be expanded to 33 nm even over transoceanic distances. It is also shown that the transmission performance of Raman amplifiers, which is dominated by not only OSNR but nonlinear effects, is superior to that of EDFAs     

A Straight-Line 160-Gb/s DPSK Transmission Over 1000 km With Time-Domain Optical Fourier Transformation

A straight-line 160-Gb/s 1000-km differential phase-shift keying transmission was successfully demonstrated with time-domain optical Fourier transformation (OFT) without employing polarization multiplexing or Raman amplification. The OFT greatly reduced the transmission impairments caused by linear perturbations, and transmission performance close to the amplified spontaneous emission limit was achieved.     

Reduction of Raman MPI and noise figure in dispersion-managed fibre

Raman amplification in dispersion-managed fibre is studied experimentally. In positive-dispersion (+D)/inverse-dispersion (-D) configuration, severe multipath interference impairments at high Raman gain are observed. These are eliminated by using the +D/-D/+D configuration. In addition, the Raman gain in the +D/-D/+D configuration starts earlier in the span, improving the noise figure dramatically over conventional transmission fibres     

New Raman pump module for reducing pump-signal four-wave-mixing interaction in co-pumped distributed Raman amplifiers

We propose a new Raman pump module that effectively reduces four-wave-mixing (FWM) nonlinear interaction among longitudinal pump modes and wavelength-division-multiplexed (WDM) signals in co-pumped distributed Raman amplifiers based on nonzero dispersion-shifted fibers (NZ-DSFs). Theory and experiments confirm that the proposed pump module structure, based on polarization- and wavelength-multiplexed Fabry-Perot lasers, allows distributed amplification with high co-propagating on-off Raman gain, providing a key technology for all-Raman-based dense-WDM ultralong-haul transmission.     

硫化铅掺杂石英玻璃光纤喇曼增强特性研究

普通单模光纤的喇曼增益低,严重制约了喇曼放大器的发展。因此,研究高喇曼增益的光纤具有重要意义。研究了硫化铅掺杂石英玻璃光纤的喇曼散射增强特性。采用改进的化学气相沉积(MCVD)法分别制备出硫化铅掺杂石英玻璃光纤和普通单模光纤样品,并测得其传输损耗谱和喇曼光谱,实验结果表明:硫化铅掺杂石英玻璃光纤具有更强的喇曼散射强度。在不同的泵浦功率条件下,分别进行了喇曼放大实验,相比于普通单模光纤,硫化铅掺杂石英玻璃光纤具有更大的喇曼增益。     

800 Gbit/s (80×10.66 Gbit/s) transmission over 3200 km ofnon-zero dispersion shifted fibre with 100 km amplified spans employingdistributed Raman amplification

80×10.66 Gbit/s wavelength division multiplexing transmission over 3200 km fibre with 100 km amplifier spacing and 50 GHz channel spacing is demonstrated. Error-free transmission of all 80 channels is achieved by employing distributed Raman amplification, forward error correction and low dispersion slope TrueWave^R fibre     

Ultra-wideband optical amplification with 3 dB bandwidth of 65 nmusing a gain-equalised two-stage erbium-doped fibre amplifier and Ramanamplification

A 3 dB gain-reduction bandwidth up to 65 nm (1549-1614 nm) is achieved using a two-stage erbium-doped fibre amplifier, together with an intermediate equaliser and Raman amplification in the transmission fibre     

Penalty-free 10 Gbit/s single-channel co-pumped distributed Ramanamplification using low RIN 14xx nm DFB pump

A penalty-free 10 Gbit/s single-channel transmission with co-pumped distributed Raman amplification using a novel high power, low relative integrity noise (RIN), multimode 14xx nm distributed feedback pump is reported. No penalty from pump to signal RIN transfer was observed with co-pumped Raman gains up to 6 dB large effective area fibre (LEAF). In contrast, 0.5 dB penalty was observed with a fibre Bragg grating stabilised pump at 6 dB of Raman gain     

Ultra-low-loss (0.1484 dB/km) pure silica core fibre and extensionof transmission distance

A pure silica core fibre with unprecedented low-loss of 0.1484 dB/km has been successfully fabricated. With a large effective area of 118 μm², this ultra-low-loss fibre extends transmission distance by 33% compared to conventional Ge-SMF, and over 400 km distance transmission is possible with Raman amplification     

分布式光纤喇曼放大技术及其在WDM系统中的应用

介绍了分布式光纤喇曼放大技术的原理、特点和应用 ,并从受此影响的 WDM传输系统的信噪比、噪声指数和品质因数三个方面讨论了光纤喇曼放大技术在提升光纤通信系统性能方面的重要作用。     

Bit-Error-Rate Evaluation of the Distributed Raman Amplified Transmission Systems in the Presence of Double Rayleigh Backscattering Noise

A new exact bit-error-rate evaluation method for distributed Raman amplification transmission systems in the presence of both amplified spontaneous emission and double Rayleigh backscattering (DRB) is developed based on a study of statistical characterization of DRB     

Novel optical hybrid line configuration for quasi-losslesstransmission by distributed Raman amplification

We propose a novel lossless transmission line configuration which exhibits significantly small signal power variation along the line by Raman amplification. A hybrid line consisting of two fibers with different Raman gain properties is theoretically investigated, and it is shown that signal power deviation can be suppressed to only 1.2 dB in a 50-km span. Validity of the proposed hybrid line is confirmed by experiments