A Dispersion Flattening Dispersion Compensating Fiber Design for Broadband Dispersion Compensation

An efficient dispersion compensating fiber (DCF) design is proposed based on a coaxial fiber structure, which provides dispersion compensation over a broad wavelength region matching that of an erbium-doped fiber amplifier gain spectrum. The design can provide dispersion coefficient that is nearly twice those of existing DCF designs. Due to the basic nature of the dispersion curve of this design, the total link dispersion cannot only be compensated but also can be flattened.     

Fabrication of High-Performance Dispersion Compensating Fiber by Plasma Chemical Vapor Deposition

In this paper, the dispersion compensating fiber (DCF) with figure of merit larger than 200 at 1550 nm has been fabricated by plasma chemical vapor deposition (PCVD). PCVD allows for a more precise and fine control of the refractive index. In addition, as the efficiency of PCVD is relatively much higher, DCFs can be fabricated faster with less material, which will reduce their cost.     

混合型光纤喇曼放大器增益和带宽的研究

混合型色散补偿光纤喇曼放大器由普通G652光纤和色散补偿光纤(DCF)组成,包括:DCF +G652、G652 +DCF和 G652+DCF +G652。讨论了它们的工作原理.使用FRA-OptiAmplifier4.0软件对其进行了优化设计,最佳结构为G652 +DCF.它可补偿光纤网络的色散,扩展通信波长范围.1427 nm的喇曼激光器作为激发源,用Q8384光谱分析仪测量了光纤的喇曼增益谱和小信号放大光谱,混合型色散补偿光纤喇曼放大器在S带和C带具有88 nm的增益带宽,这增加了光纤通信网络的传输通道.     

Dispersion Compensation in Externally Modulated Transmission System Using Chirped Fiber Grating

We present an externally modulated NTSC AM-VSB erbium-doped fiber amplifier (EDFA)-repeated system in the 1550 nm region which uses a chirped fiber grating (CFG) as a dispersion compensation device. In contrast to the conventional externally modulated fiber optical CATV systems, either with or without dispersion compensation fiber (DCF), good performances of carrier-to-noise ratio (CNR) S 50 dB, composite second order (CSO) S 74 dB, and composite triple beat (CTB) S 65 dB were achieved for the full channel band after a 100-km single-mode fiber (SMF) transmission.     

Dispersion Compensation in Externally Modulated Transmission System Using Chirped Fiber Grating

We present an externally modulated NTSC AM-VSB erbium-doped fiber amplifier (EDFA)-repeated system in the 1550 nm region which uses a chirped fiber grating (CFG) as a dispersion compensation device. In contrast to the conventional externally modulated fiber optical CATV systems, either with or without dispersion compensation fiber (DCF), good performances of carrier-to-noise ratio (CNR) ≥50 dB, composite second order (CSO) ≥74 dB, and composite triple beat (CTB) ≥65 dB were achieved for the full channel band after a 100-km single-mode fiber (SMF) transmission.     

An Efficient Dispersion Calculation Method for Axially Symmetric Optical Fibers

An efficient numerical modal calculation method for an axially symmetric optical fiber is presented using a numerical Galerkin's method. By decomposing the transverse electric field of a guided wave with Bessel functions of the first kind in cylindrical polar coordinates, we have shown that dispersion characteristics of an optical fiber can be obtained very easily. In order to illustrate the effectiveness of this suggested method, numerical examples are given for a step index fiber, a W-shape depressed inner cladding fiber, and a dispersion-flattened fiber.     

光纤传输过程中的色散特性

基于光纤传输对于光纤通讯技术的重要意义,数值模拟光纤传输过程中的色散关系,得到随着光纤长度的增加,光纤传输中比特率减小,当入射波长为1.28μm时,光纤色散为0ps·nm<'-1>km<'-1>,研究结论为光纤传输器件设计提供理论依据.     

Spot Size Technique: A Theoretical Approach To Optimize Dispersion Compensated

Using a spot size based optimization technique, a bend loss versus dispersion diagram has been obtained theoretically for the most widely used step-index disper sion compensated optical fibers (DCF). The Rayleigh scattering loss can be incorpo rated with bend loss to calculate figure of merit (FOM), thus giving an FOM versus dispersion curve on a single diagram. The plot of the FOM-dispersion curve on a single diagram is useful from the designer's point of view, as it provides a quick reference for choosing the best suitable DCF, which should have large negative dispersion as well as maximum possible value of FOM. The effect of fiber manufac turing losses such as absorption loss on the maximum value of FOM has also been estimated.     

Origin and System Effects of Polarization Mode Dispersion in Chirped Bragg Gratings

Polarization mode dispersion of chirped Bragg gratings is analyzed in terms of key birefringence phenomena and impact on telecommunication systems performance. The influence on polarization mode dispersion (PMD) of fiber birefringence, grating chromatic dispersion, and ripples of the group delay curve is pointed out. Polarization mode dispersion influence on systems performance is investigated by numerical simulations and transmission experiments at 10 Gbit/s. The deterministic nature of Bragg gratings PMD determines a moderate, upper-limited system penalty for a transmission line employing a single compensating device. However, in the case of broadband components, a non-negligible PMD penalty may be observed due to the difficulty of controlling accurately the group delay linearity.     

高速色散补偿系统中喇曼放大器性能研究

利用喇曼放大器的非线性偏微分耦合方程组,对带喇曼放大器的色散补偿系统进行了仿真,并与传统的仿真方法进行了比较.结果表明:在色散完全补偿系统中,当传输速率较高时,忽略色散后的传统仿真方法的结果,与采用色散补偿技术后使整个系统色散为零的仿真结果有一定偏差,此时不能忽略色散的作用.还对前补偿系统和后补偿系统进行了研究,利用Q值性能判别法,分别得到了信号光脉冲的最佳占空比和最佳脉冲阶数.     

Third-Order Dispersion in Linearly Chirped Bragg Gratings and Its Compensation

When fiber optics' quadratic dispersion is compensated, the cubic dispersion determines the transmission quality in an optical link. Although the third-order dispersion coefficient is small in standard fiber optics at the third window, it is not in the linearly chirped grating used to the second-order dispersion equalization. The influence of the grating parameters on its third-order dispersion value is systematically studied and an efficient and low-cost device is proposed thatis numerically proven to cancel the global third-order dispersion that arises from the optical link.     

优化二元相位取样光纤布喇格光栅及对色散和色散斜率补偿的应用

利用粒子群算法对二元相位取样光栅的周期相位调制进行优化设计，在此基础上提出了基于二元相位取样光纤布喇格光栅的色散和色散斜率补偿技术.通过光栅周期啁啾可以调整每个信道的带宽，色散量由子光栅长度决定，调整取样函数的啁啾系数可以改变色散斜率，因此可以设计出用于波分复用系统的多信道色散补偿器件.     

间插取样光纤光栅多通道色散补偿器

对间插取样光纤光栅（ISFBG）进行了理论分析和仿真,给出了ISFBG的折射率表达式,提出了一种在较低的折射率调制深度条件下实现通道间平坦度较好的色散补偿器的制作方法.实验制作了由两个取样光纤光栅间插而成的10通道色散补偿器,其时延抖动大都小于20 ps,通道间平坦度小于1 dB.     

硅狭缝光波导的色散特性及其色散补偿应用的研究

对硅狭缝光波导色散特性进行了数值研究.研究结果表明,在1.55μm工作波长附近,硅狭缝光波导色散随结构参量的改变而改变,一般在-1000ps/(nm·km)以下,最大可达到-6700ps/(nm·km)左右,同时其相对色散斜率可小于0.009nm-1.因此,选取合适的结构参量,硅狭缝光波导可被用于补偿高速宽带光通信链路的残余色散,且比现有的色散补偿光纤具有一定的优势.     

通信系统中色散补偿光纤的研究

对五包层色散补偿光纤进行了研究,分析了各个参量对色散补偿光纤性能的影响,发现色散补偿光纤只有在一定范围的拉丝芯径内,以牺牲负色散数值为代价才能获得较大的负色散斜率。在1550nm处获得了不大于150ps/(nm·km)的负的总色散和负色散斜率的色散补偿光纤。采用在光纤拉丝时旋转预制棒的工艺减小了光纤的偏振模色散,并采用化学汽相沉积(MCVD)光纤生产工艺,研制出了性能较好的色散补偿光纤。     

全固双层芯色散补偿光子晶体光纤的研究与设计

为了补偿光纤色散对高速信号传输的限制,提出一种全固双层芯色散补偿光子晶体光纤.首先对该光纤模式耦合特性进行理论分析,然后利用多极法进行模拟计算,得到该光纤包层结构参数与色散值以及相位匹配波长之间的关系,并对其规律进行研究.通过优化光纤结构参数,得到在1 550nm处,色散值达到-32 620ps/(nm·km)、损耗为0.29dB/km、与标准单模光纤的熔接损耗为4.77dB的色散补偿光纤.该光纤可补偿1 910多倍长度的SMF-28单模光纤的色散,补偿能力远大于常规色散补偿光纤.与空气孔-石英结构色散补偿光子晶体光纤相比,全固色散补偿光子晶体光纤具有易制备、易与传统通信光纤熔接等优点.     

Dispersion compensation using mismatched multicavity etalon all-pass filter

In this paper, we propose a novel mismatched multicavity etalon (MME) all-pass filter for fixed-value dispersion compensation and dispersion slope compensation. It is a multicavity Gires-Tournois (GT) etalon filter with unequal cavity lengths between adjacent cavities. A theoretical study is presented. Analytical expressions for the group delay and chromatic dispersion are derived to allow device designs to be made. The simulation results show that nearly linear group delay or quasi-flat chromatic dispersion response can be obtained by suitably choosing the reflectances of the reflectors and the cavity mismatch length. The chromatic dispersions and the bandwidth of the quasi-flat-dispersion band can be tailored by changing the reflectances of the reflectors and the mismatched cavity length. The dispersion slope compensation can be obtained by slightly modulating the reflectances of the reflectors. Increasing the number of cavities can enhance the performance and the design flexibility of the dispersion compensator.     

Origin and System Effects of Polarization Mode Dispersion in Chirped Bragg Gratings

Polarization mode dispersion of chirped Bragg gratings is analyzed in terms of key birefringence phenomena and impact on telecommunication systems performance. The influence on polarization mode dispersion (PMD) of fiber birefringence, grating chromatic dispersion, and ripples of the group delay curve is pointed out. Polarization mode dispersion influence on systems performance is investigated by numerical simulations and transmission experiments at 10 Gbit/s. The deterministic nature of Bragg gratings PMD determines a moderate, upper-limited system penalty for a transmission line employing a single compensating device. However, in the case of broadband components, a non-negligible PMD penalty may be observed due to the difficulty of controlling accurately the group delay linearity.     

Cross-phase modulation in long-haul systems with chirped fiber Bragg gratings-based dispersion compensators

The cross-phase modulation (XPM) effect in fiber links with dispersion compensated by chirped fiber Bragg gratings (CFBGs) is analyzed here for the first time. A continuous-wave (CW) signal, referred to as a probe, is used to investigate the impact of XPM on communication systems. The result shows that the XPM in systems using CFBGs as dispersion compensators is greatly suppressed, compared with that of systems using dispersion compensated fiber (DCF). The difference of the dispersion management between the system using DCF and that using CFBGs is demonstrated, too.     

基于激光拍频实现啁啾光纤光栅色散的测量

以啁啾光纤光栅为例,研究了激光拍频的产生机制,并建立对啁啾光纤光栅色散的测量模型.详细阐述了系统结构和测量原理,并对测量结果和理论值进行了分析与比较,结果一致性较好.在频谱分析仪分辨率为2.5kHz的情况下,色散测量准确度可以达到0.1ps,啁啾光纤光栅色散的实际测量也证实了该系统的可行性,系统相对简单,测量准确度高,可为色散测量提供参考.