Compensation of dispersion in optical fibers for the 1.3-1.6 μmregion with a grating and telescope

The transmission of ultrashort optical pulses over long distances in optical fibers is limited by pulse broadening due to group velocity dispersion. A grating and telescope dispersion compensator with group velocity dispersion of equal magnitude and opposite sign can compensate for the fiber dispersion. The possible benefits of such dispersion compensation in the 1.3-1.6-μm wavelength region are investigated. The results show that compensation of first-order dispersion at 1.55 μm in a fiber with zero dispersion near 1.3 μm is primarily limited by the second-order dispersion of the grating and the telescope compensator. For a wavelength slightly greater than the zero dispersion wavelength, both the first- and second-order group velocity dispersion can be canceled by the grating and telescope dispersion compensator, allowing transmission exceeding 100 Gb/s over 100 km     

一种闭环控制的光纤光栅动态色散补偿仪

利用啁啾光纤光栅的应变调谐特性，将色散补偿的啁啾光纤光栅斜贴于悬臂梁的侧面，通过应力实现啁啾量调整而改变其色散补偿量的大小，同时利用固定在同一悬臂梁的均匀布拉格光栅传感器，实现了闭环自动控制色散补偿量，研制出了一种新型的光纤光栅动态色散补偿仪。该色散补偿仪工作在1550nm波段，典型性能数据为：色散动态补偿范围-1000-1680ps／nm，插入损耗小于1．5dB，动态调谐步进响应时间小于50ms，基本上能满足10Gb／s光纤通信系统中色散动态补偿的要求。     

宽带可调谐光纤光栅色散补偿器系统设计

文章提出一种在光纤光栅自身热膨胀效应产生啁啾的基础上,利用铝片热膨胀系数比较高的特点产生应力来增强光纤光栅啁啾,从而实现了宽带、大范围色散调谐的新型光纤光栅色散补偿器。该色散补偿器能够分别对群速度色散及中心波长独立调谐。实验结果表明,在中心波长为1 551.25nm处,能够实现>1.5nm的色散补偿带宽,-350～-690ps/nm的群时延色散调谐范围;在色散为-660ps/nm情况下,能够实现中心波长1nm的偏移。     

Tunable dispersion equalizer with a divided thin-film heater for40-Gb/s RZ transmissions

We have developed tunable dispersion equalizers with a chirped fiber grating on the divided thin-film heater. The divided thin-film heater took an important role in the control of dispersion and dispersion slope. We successfully demonstrated the dispersion control from -304 to -196 ps/nm, the dispersion slope control from +100 to -300 ps/nm², and good performance in 40-Gb/s return-to-zero transmission by using this tunable dispersion equalizer     

线性啁啾布拉格光纤光栅的色散补偿特性研究

本文将全面分析Ｃｈｉｒｐｅｄ Ｂｒａｇｇ光纤光栅的色散特性，并对色散特性作一定性分析，利用耦合模方程导出ＣｈｉｒｐｅｄＢｒａｇｇ光栅的反射率方程，从而推导出Ｃｈｉｒｐｅｄ Ｂｒａｇｇ光纤光栅的色散计算公式，然后，引入微波领域的“品质因素”概念，从而量化了色散补偿器的补偿能力。     

Tunable dispersion device based on a tapered fiber Bragg grating and nonuniform magnetic fields

We present a new variable dispersion device based on tuning the chirp of a tapered fiber Bragg grating by means of a magnetic transducer. By using a nonuniform magnetic field, we demonstrate a 188-472-ps/nm dispersion tuning range, suitable for tunable radio-frequency filters and dispersion compensation, among others.     

光纤—光纤光栅脉冲压缩器的研究

本文提出了利用正常色散光纤加线性啁啾光纤光栅组成全光纤光脉冲压缩器方案,理论和数值分析了压缩器的压缩特性,给出光纤－光纤栅压缩器的设计规则,指出了有关文献压缩器设计规则的局限性,提出了新结论。     

均匀光纤光栅Chirp化及其用于色散补偿实验研究

对均匀光纤光栅进行了线性啁啾（Chirp）化处理,并将由此得到的Chirp光纤光栅用于常规的单模光纤通信系统进行色散补偿,给出了均匀光纤光栅Chirp化原理和实验结果及Chirp光纤光栅色散补偿原理和实验结果。     

光栅参数对折射率剖面非均匀取样光纤光栅的影响

利用传输矩阵法,数值分析了光栅参数对折射率剖面非均匀的均匀光纤光栅及取样光纤光栅的透射谱、偏振关系损耗和偏振模色散的影响。计算结果表明,均匀光纤光栅的光栅条纹可见度及光栅周期对其偏振关系损耗和偏振模色散影响很大;改变取样光纤光栅的取样周期及光栅段长度,透射谐振峰的幅度、偏振关系损耗和偏振模色散的最大值均随取样光纤光栅长度的增加而递增。与靠近中心波长的谐振峰相比,折射率剖面非均匀导致的双折射对取样光纤光栅远离中心波长的谐振峰的影响较小。     

Pulse evolution in a photorefractive self-pumped phase conjugatorwith transmission grating geometry

The effect of grating dispersion on pulse evolution in a photorefractive self-pumped phase conjugator is analyzed. The broadening factors and the time-dependent phases of self-pumped phase-conjugate pulses of unchirped and chirped Gaussian pulses are obtained. When the grating dispersion and the angular dispersion cancel the material dispersion, the self-pumped phase-conjugate pulse has a minimum width, which is determined by the first-order dispersion of the grating. The self-pumped phase conjugation of an unchirped Gaussian pulse broadens and is linearly chirped whereas the self-pumped phase conjugation of a chirped Gaussian pulse is compressed when the dispersion-induced chirp cancels the initial chirp     

WDM系统中啁啾光纤光栅带外色散的影响

对啁啾光栅阻带外的色散特性进行了深入理论分析，在WDM系统中往往需要光栅级联来完成单个光栅不能实现的功能，级联光栅时，前面光栅的阻带外色散要对接续在其后面的光栅产生影响，增大了光栅的时延波动。对光栅级相互间的影响进行了理论分析与实验验证，提出了降低光栅间相互影响的方法是降低调制或光栅切趾，在光栅级联时采用高阶高斯切趾的效果最好。     

光纤通信系统中色散补偿的研究

本文从光纤色散和啁啾光栅所提供的延时两方面对光通信系统中的色散补偿进行了分析，表明每隔放大器的中继距离插入一啁啾光栅进行色散补偿可实现信号无失真传输，在此基础上提出了在中继器中同时实现全光信号放大和色散补偿的光纤通信系统方案。     

Bragg光纤光栅色散补偿的理论分析与研究

阐明了光纤的色散即脉冲的展宽这一基本概念；从光的波动理论出发，导出了Bragg光纤光栅色散的基本方程；讨论了Bragg光纤光栅的色散补偿特性和它的局限性。     

Tunable Dispersion and Dispersion Slope Compensator Using Strain-Chirped Fiber Bragg Grating

We propose a tunable dispersion and dispersion slope compensator based on induced strain-chirp in a uniform fiber Bragg grating. A specially designed mechanical rotator concatenated with a metal beam with linear thickness variation along its height was used to induce a quadratic strain gradient along the grating. We successfully demonstrated the dispersion and dispersion slope change by adjusting the rotation angle and feasibility of dispersion and dispersion slope compensation at 160-Gb/s nonreturn-to-zero transmission by simulation     

Ramped, unchirped fiber gratings for dispersion compensation

The effective medium method is used to analyze an unchirped fiber grating in which the coupling strength between the light field and grating is monotonically increasing with penetration depth into the grating. The potential use of this type of grating for dispersion compensation in intensity modulated optical systems is discussed. It is shown that, when this type of grating is used in reflection, appropriately designed linearly ramped gratings can be used to compensate fiber dispersion over a wide range of bandwidth-distance product values. In contrast, when the grating is used in transmission, there are strong limits on the bandwidth-distance product     

优化啁啾光栅耦合系数分布改善其色散特性

在对线性啁啾光栅的反射率峰值和带宽进行计算的基础上,结合新定义的光栅色散统计二阶矩构造出一个较全面反映光栅特性的品质因数。通过比较得出一组最佳的品质因数调节参数,并用于对光栅耦合系数高斯分布形状和耦合长度进行优化,最终获得了最佳的色散特性。结果表明本文提出的方法是一种能有效地优化光栅结构的定量方法。     

Plasmon dispersion for a modulated two-dimensional electron gas

Raman scattering measurements of the dispersion of intrasubband plasmons in a two-dimensional electron gas under a biased linear metal grating are presented. The momentum resolution of the Raman experiment allows a large range of wavevectors to be probed, both perpendicular and parallel to the grating fingers; in both configurations, grating assisted scattering from plasmon modes is observed. The plasmon dispersion showed gaps at the boundaries of the mini-Brillouin zones defined by the grating periodicity. Semi-classical calculations of the electrodynamics of the system, based on a scattering matrix approach, demonstrate that these energy gaps are due both to the periodic screening effects of the grating and to a lateral modulation of the electron density. The form of the plasmon dispersion was analysed from calculations of the dielectric response of a modulated two-dimensional electron gas.     

Dispersion-order selectable chromatic dispersion compensator using strain-profile modification blocks

A new method for tuning the dispersion profile of a fiber grating is described. The method involves compressing the fiber grating attached to a structure in which the cross-sectional area varies with its position. Because the cross-sectional area defines the compression rate, the local Bragg reflection wavelength that determines the dispersion profile varies along the position. A structure in which the cross-sectional area can be simply altered by inserting-extracting a part of structure was designed. Therefore, the dispersion order of the fiber grating attached to the structure can be selected. Using the method, a linearly-quadratically chirped fiber grating was made and various group delay slopes depending on the applied stress were obtained.     

Grating compensation of third-order fiber dispersion

Subpicosecond optical pulses propagating in single-mode fibers are severely distorted by third-order dispersion even at the fiber's zero-dispersion wavelength (λ₀). Using cross-correlation techniques, the authors measured the broadening of a 100-fs pulse to more than 5 ps after passing through 400 m of fiber near λ₀. The measured asymmetric and oscillatory pulse shape is in agreement with calculations. A grating and telescope apparatus was configured to simultaneously equalize both third- and second-order dispersion for wavelengths slightly longer than λ ₀. Nearly complete compensation has been demonstrated for fiber lengths of 400 m and 3 km of dispersion-shifted fiber at wavelengths of 1560-1580 nm. For the longer fibers, fourth-order dispersion due to the grating becomes important     

Tunable dispersion compensator based on a fiber Bragg grating written in a tapered fiber

We report a novel dispersion tunable device for first-order dispersion compensation. It is based on a fiber Bragg grating written in a tapered fiber with a specific profile. The taper profile allows tuning the dispersion of the grating by stretching the fiber while the linearity of the group delay is preserved. A device with 0.8 nm of useful bandwidth and dispersion value tunable over more than 400 ps/nm is reported.