啁啾sinc取样光纤光栅研究

提出了一种特殊的取样光纤光栅：啁啾sinc取样光纤光栅.研究表明,对于均匀光纤光栅进行啁啾sinc取样,可以实现色散斜率补偿和获得精确的反射波长数控制;对啁啾光纤光栅进行啁啾sinc取样,则能够实现色散和色散斜率的同时补偿,并且可以进行精确的波长数控制及获得各信道一致的反射率.利用啁啾sinc取样光纤光栅,可以对各种传输光纤进行色散和色散斜率的补偿.     

40Gb/s光时分复用传输光纤光栅补偿色散研究

用精密扫描掩模法写入宽阻带啁啾光纤光栅,掩模板背面两端各10％长度处镀有按4阶高斯函数透过率的膜,写入的啁啾光栅的时延纹波最大值为20ps。为减少写入光纤光栅的偏振模色散,研制了新的低偏振模色散光纤光栅补偿写入法。采用补偿写入法前的平均微分群时延为9．1406 ps;采用补偿写入法后的平均微分群时延为0．1521 ps。并利用低偏振模色散光纤光栅对40Gb／s光时分复用系统在普通G．652光纤传输122km的色散进行了补偿实验,功率代价为1．5dB。     

基于啁啾光纤光栅的色散补偿器在超长距离密集波分复用系统中的应用

对啁啾光纤光栅在超长距离多波长传输系统中应用时所存在的问题进行了研究，主要分析了多波长级联的啁啾光纤光栅之间的串扰，并提出了利用相干长度法来抑制不同信道间啁啾光纤光栅串扰的方法.在此基础之上实现了基于光纤光栅色散补偿的8×10Gbit/s,1500km G.652光纤上的传输系统. 关键词： 光纤通信 色散补偿 啁啾光纤光栅     

线性啁啾光纤Bragg光栅的实验研究

本文给出了142mm长相位掩模板和扩束技术研制的色散补偿线性啁啾Bragg光纤光栅(CFBG)的反射谱特性及传输实验结果,本实验研制的线性啁啾Bragg光纤光栅样品带宽为0.56～0.92mm.可实现对普通光纤色散补偿100km以上,色散代价小于1.5dB.     

基于啁啾光纤光栅的色散管理

本文通过数值仿真对基于啁啾光纤光栅的单信道的色散管理进行了研究，并在1500km的10Gb/s单信道传输系统中进行了实验验证.本文还通过分析啁啾光纤光栅引入的信道间随机时延差对交叉相位调制的抑制作用，发现了基于啁啾光纤光栅的多信道系统的色散管理的新的特点. 关键词： 光纤通信 色散补偿 啁啾光纤光栅     

利用啁啾光纤光栅进行色散补偿的研究

分析了由于光纤的色散引起的脉冲展宽,并介绍了啁啾布拉格光纤光栅进行色散补偿的基本原理。２－５Ｇｂ／ｓ、１００ｋｍ 色散补偿的实验结果表明,利用啁啾光纤光栅进行色散补偿是一种切实可行的色散补偿方案。     

16×10Gb/s啁啾光纤光栅色散补偿系统性能研究

运用啁啾光纤光栅法对在G.652光纤传输的16×10 Gb/s信号实现色散补偿数值模拟和研究,分析了入纤光功率、色散斜率以及啁啾光纤光栅色散补偿带宽对系统误码率的影响,结论是:入纤光功率在8～16 dBm之间时系统的性能较好;啁啾光纤光栅的色散补偿带宽对系统的影响较大;光纤的色散斜率对系统误码率有一定的影响.     

变迹对啁啾光纤光栅色散补偿性能的影响

利用传输矩阵法对啁啾光纤光栅的光学特性进行了数值求解,同时对啁啾光纤光栅进行了变迹处理,使用两种常用的变迹函数获得了较理想的光学特性,在此基础上构造了一种新的变迹函数,通过仿真结果表明,与常用的变迹函数所得到的光学特性相比,具有更宽的反射谱,更平稳的色散曲线,时延特性的线性度更好,使得啁啾光纤光栅作为色散补偿器的色散补偿性能更好.     

一种有效的色散补偿镜优化设计方法

介绍了一种有效的色散补偿镜优化设计方法.这种方法将广义模拟退火法和最小二乘法结合起来使用.在色散补偿镜的设计过程中,用双啁啾结构作为初始膜系,发现了一些设计双啁啾结构应注意的规律.这种新的优化方法避免了局部陷阱问题,最终结果也比较令人满意.此外,这种优化设计方法还可以应用于设计啁啾光纤光栅.     

薄包层啁啾长周期光纤光栅的色散补偿

为了提高啁啾长周期光纤光栅(LPFG)光纤通信的色散补偿能力,提出了利用薄包层啁啾LPFG进行包散补偿的方法.首先介绍了根据传输信号确定啁啾LPFG的啁啾系数、光栅长度等参数的方法.然后利用上述方法设计了对光纤中传输的中心波长为1550 nm,带宽为0.2nm的信号进行色散补偿的薄包层啁啾LPFG.利用耦合模理论及传输矩阵法计算了约1m长的此种啁啾LPFG的色散,结果表明可以补偿该光信号通过46 km光纤所产生的色散.进一步分析了切趾函数、啁啾系数、交叉耦合系数等参数对薄包层啁啾LPFG色散的影响.     

Influence of the birefringence autocorrelation function on the polarization mode dispersion of constantly spun fibers

We show that the polarization mode dispersion of a constantly spun, single-mode fiber is strongly influenced by the autocorrelation function of its birefringence. In particular, under probable conditions, the mean square differential group delay of the spun fiber may even be higher than the delay that the same fiber would have if it were not spun.     

折射率直流分量调制对光纤Bragg光栅的影响

从耦合模理论出发,推导了折射率直流分量调制函数与光纤Bragg光栅相位之间的关系式,分析了折射率直流分量调制对光纤Bragg光栅时延特性的影响.利用传输矩阵法进行了数值仿真,仿真结果与理论分析一致.在理论分析基础上,提出采用同一块均匀相位掩膜版灵活制作具有不同线性或非线性时延特性的啁啾光纤光栅的方法,可用于高速光通信系统中不同色散和色散斜率的补偿.     

Pulse shortening and quality improvement based on spectral filtering in a stretched-pulse mode-locked fiber laser with large third-order dispersion

We demonstrate a passively mode-locked ring fiber laser operating in the stretched-pulse regime. The ring cavity model is constructed with standard single-mode fiber and dispersion delay line for dispersion management. Here, all-solid Yb-doped photonic bandgap fiber is used as the dispersion delay line and provides laser gain simultaneously. As the all-solid Yb-doped photonic bandgap fiber has large third-order dispersion, it is necessary to study its impact on the stretched-pulse operation. The presence of the third-order dispersion reduces pulse quality because of the relatively small group velocity dispersion. To improve the pulse quality, a spectral filter is employed in the model. The simulation results show that spectral filtering could improve the pulse quality and shorten the pulse duration. Meanwhile, the optimum filter bandwidth is studied.     

Optimization of the apodization strength of linearly chirped Bragg gratings for span dispersion compensation

We present an optimization process for the apodization strength factor of fiber Bragg grating dispersion compensators. It will be demonstrated that a proper choice of the apodization strength factor results in minimum deviation of the dispersion from the required level, maximum reflection bandwidth and minimum group delay ripple impact, thus leading to a reduction of the Q-factor penalty of the dispersion compensating system. We also discuss the influence of the fiber link length in the determination of the optimum apodization strength factor, taking into account that shorter links minimize the group delay ripple amplitude, whereas the longer ones maximize the bandwidth of interest. It is determined that a fiber link length of ～80 km can balance the requirements of group delay ripple impact and bandwidth. The results obtained through this analysis allow a faster modeling of the Bragg grating parameters in order to achieve an improved spectral performance, as well as a cost-effective fabrication process.     

利用非均匀镀铜技术实现光纤光栅的色散可调

提出了一种利用非均匀镀铜技术在光纤光栅的外包层镀上径向均匀轴向厚度渐变的铜膜,通过温度控制来调节光纤光栅的啁啾量,从而实现光纤光栅的色散可调,用于动态的色散补偿。在理论方面,建立了完整的热平衡方程,对轴向厚度渐变镀铜膜光纤光栅在温度控制下的受力情况进行分析;分析了光纤光栅在同时受到温度变化和非均匀应力时的反射、时延、色散等特性,并进行了数值仿真。在实验方面,在自制的均匀光纤光栅上利用先真空镀后电镀的方法镀上了轴向厚度渐变的铜膜,并对镀膜后的光纤光栅利用温度调节装置进行测试,不同温度变化下光纤光栅的特性和理论仿真结果基本一致,从而验证了理论分析的正确性。     

高双折射光子晶体光纤偏振模色散测量

对一种高双折射光子晶体光纤的偏振模色散进行了测量.实验用26 m长光子晶体光纤使皮秒光脉冲的两个正交偏振模产生了108 ps时延.运用脉冲时延法和固定分析仪法对这种高双折射光子晶体光纤的偏振模色散进行了实验测量，测量得到其偏振模色散参量可达4154 ps/km，对应的模式双折射度为1.25×10－3.这种新型的高双折射光纤可用于补偿光纤通信系统中的偏振模色散.     

Strained Chirped Fiber Bragg Gratings Based all-fiber Variable Optical Delay Line for Optical Coherence Tomography

We present the novel all-fiber optical delay line that can be realized by exploiting the fundamental distributive reflection characteristics of a chirped fiber Bragg gratings (CFBG). With the assist of a strained CFBG and a designed fiber stretcher, the proposed delay line could perform the function (such as attainment of variable large enough optical delay without dispersion mismatch) of the conventional optical delay line within the optical fiber. While the strained CFBG produced 3.1 mm optical delay, the pair of CFBGs in the opposite direction can manage dispersion imbalance of the delay line. The use of the PZT-based fiber stretcher can enable depth scanning at a high repetition rate for real-time imaging. The performance of the delay element is demonstrated with measured experimental results. OCT system embedded with the all-fiber variable optical delay line showed the axial resolution of 100 μm and the dynamic range of 50 dB. The implemented system was used for the imaging of a biomedical sample, which proves the utility of the proposed delay element as a promising alternative of optical delay line.     

低串扰的多波长光纤光栅色散补偿器

分析了光纤光栅色散补偿系统中的串扰，并比较了几种常用的多波长光纤光栅色散补偿器的串扰特性，结合串联的窄带光纤光栅和取样光纤光栅的优点，提出一种抑制光纤光栅色散补偿系统串扰的方法.它通过在邻近信道间引入随机时延差，既能改善取样光纤光栅的线性串扰特性，又能抑制交叉相位调制效应和四波混频等非线性串扰.使用该方法可以得到具有低串扰的多波长光纤光栅色散补偿器.