Purely phase-sampled fiber Bragg gratings for broad-band dispersion and dispersion slope compensation

We demonstrated numerically that both the chromatic dispersion and the dispersion slope can be compensated by using purely phase-sampled superstructure fiber Bragg gratings provided both the grating period and the sampling period are chirped linearly along the grating. Adjusting the refractive index modulation and the chirp of sampling function, they can be designed to compensate dispersion of a large number of wavelength-division-multiplexing channels.     

Fiber Bragg grating fabrication for dispersion slope compensation

Group-delay dispersion slope causes signal deterioration in long-distance high-data-rate communication systems. We report the fabrication of high-quality apodized and chirped fiber gratings with dispersion slopes as high as -1800 ps/nm/sup -2/ over a 0.7-mn bandwidth-sufficient to compensate for the dispersion slope of >25000-km length of standard fiber at a wavelength of 1550 nm. We believe this is the first time that fiber Bragg gratings have been specifically designed and fabricated for dispersion slope compensation. The fabrication technique uses a standard unchirped phase mask and two scans of the inscribing UV beam.     

Phased-only sampled fiber Bragg gratings for high-channel-count chromatic dispersion compensation

Binary and multilevel phase-only sampling functions are proposed for the sampled fiber Bragg gratings (FBGs) with high channel count, which require significantly less refractive-index modulation than that does the sampled grating with amplitude sampling. The design using the new simulated quenching optimization with temperature rescaling results in high channel uniformity and minimum energy in the out-of-band channels. The technique can be applied to the sampled FBGs with very high channel count. A five-channel nonlinearly chirped multilevel phase-only sampled FBG for tunable chromatic dispersion compensation is demonstrated.     

Custom design of long chirped Bragg gratings: application togain-flattening filter with incorporated dispersion compensation

We present and experimentally demonstrate simple relationships between the refractive index modulation, the chirp-rate or dispersion and the transmission loss through, and reflection of, chirped Bragg gratings, and apply them to the design of a new type of gain flattening filter with incorporated dispersion compensation     

Analysis of fiber Bragg gratings for dispersion compensation inreflective and transmissive geometries

Numerical analysis of the dispersion-compensating properties of fiber Bragg gratings (FBGs) in both reflective and transmissive modes is presented. First, the sensitivity of chirped, reflective gratings to the grating chirp parameter, index modulation, and grating length is examined, showing that apodization provides lower sensitivity to variations in these parameters. Second, we introduce a new transmissive geometry for grating-based dispersion compensation that utilizes the dispersive properties of a uniform Bragg grating in transmission     

利用啁啾光纤光栅的色度色散补偿方案的研究

本文针对高速率光传输系统中的色度色散问题,利用啁啾光纤光栅,设计了后置补偿、前置补偿和混合补偿三种方案并实现了320k。的G．652光纤单信道40Gbit/s的无中继传输,仿真实验结果表明：较之后置补偿和前置补偿,混合补偿具有最好的色散补偿性能。     

Multiple stage dispersion compensation in long haul optical fibresystems using chirped fibre Bragg gratings

Modelling is used to assess the performance of an optical fibre link which has fibre grating dispersion compensators spaced at intervals along its length. A 10 Gbit/s electroabsorption modulator with high positive chirp is shown to transmit in excess of 158 km in normal dispersion fibre using two 2 cm long compensators, incurring a dispersion penalty of only 1.0 dB. Thus the transmission range is improved by a factor of 6.6 over the uncompensated case     

光纤布拉格光栅温度补偿研究

提出了一种新颖结构的光纤光栅温度补偿器件,它由两种不同的热膨胀系数的材料组成。利用该器件实现了光纤光栅的温度补偿。在-18~50℃温度范围内光栅波长变化0.028nm,是未补偿光纤光栅的1/23倍。     

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     

Dispersion compensation of fiber Bragg gratings in 3100 km high speed optical fiber transmission system

By optimizing the fabrication process of the chirped optical fiber Bragg grating (CFBG), some key problems of CFBG are solved, such as fabrication repetition, temperature stability, group delay ripple (GDR), fluctuation of the reflection spectrum, polarization mode dispersion (PMD), interaction of cascaded CFBG, and so on. The CFBG we fabricated can attain a temperature coefficient less than 0.0005 nm/℃, and the smoothed GDR and the fluctuation of the reflection spectrum are smaller than 10ps and 0.5dB, respec-tively. The PMD of each CFBG is less than 1 ps and the dispersion of each grating is larger than -2600 ps/(nm·km). With dispersion compensated by the CFBGs we fabricated, a 13×10 Gbit/s 3100 km ultra long G.652 fiber transmission system is successfully imple-mented without electric regenerator. The bit error rate (BER) of the system is below 10-4 without forward error correction (FEC); when FEC is added, the BER is below 10-12. The power penalty of the carrier-suppressed return-to-zero (CSRZ) code transmission system is only 2.5 dB.     

Electronic technique for temperature compensation of fibre Bragg gratings sensors

Optical sensors composed of fibre Bragg gratings (FBG) are becoming a choice for a wide range of sensing applications. However, in order to manufacture temperature independent sensors, it is necessary to compensate for the intrinsic temperature dependence of the FBG. In this letter we present an extremely effective, simple and low cost novel technique for stabilising the bias point of an interrogation current amplitude detection system which uses a laser diode source and a pair of matched FBGs. An electronic feedback control circuit measures the wavelength shift due to temperature variations in a reference FBG and actuates on the laser diode temperature, to induce changes in its wavelength output and compensate for the temperature dependence of the FBG sensor.     

V-I传输矩阵方法在布拉格光纤光栅分析中的运用

介绍了V-I传输矩阵方法用于布拉格光纤光栅的理论分析,该方法通过参量变换将相邻薄层间的界面矩阵退化为单位矩阵,从而大大提高了计算效率。从传输矩阵出发,数学上推导出耦合模方程,证明了该方法的正确性,有助于加深对V-I传输矩阵方法物理机制的理解。数值模拟分析发现V-I传输矩阵方法具有计算快速、简单明了的优点。最后还指出V-I传输矩阵方法仅适用于短周期光纤光栅,若要运用于长周期光纤光栅,需要进一步理论修正。     

Analysis of linearly tapered fiber Bragg grating for dispersion slope compensation

We demonstrate that linearly tapered fiber Bragg gratings (FBGs) display nonlinear group delay under strain or stress. The nonlinear group delay of the tapered FBG is analyzed theoretically. Experimental results show a good agreement with the analysis. We are the first to find that linearly tapered FBGs can be used in dispersion slope compensation.     

啁啾光纤光栅中偏振模色散的研究

首先介绍了不同种双折射率差Δn的光纤制成的啁啾光纤光栅中偏振模色散现象 ,然后说明了光栅中偏振模色散的大小与 Δ n的相关性 ,并阐述了对用于色散补偿作用的啁啾光纤光栅中偏振模色散的消除 (补偿 )方法 ,最后指出利用啁啾光纤光栅中大的偏振模色散对高速光通信系统传输线路中偏振模色散的补偿方法。     

Fiber optic cable infrastructure and dispersion compensation for storage area networks

The fiber optic cable infrastructure currently used by many large data centers is over 10 years old, and may soon require upgrading in order to support higher-data-rate services. Legacy multimode optical fiber is typically low bandwidth, and will only support limited distances at data rates exceeding 1 Gb/s. In this article we investigate various methods for extending the distance of multimode fiber at higher data rates. This includes the tactical use of enhanced bandwidth multimode fiber, electronic dispersion compensation, and wavelength tuning control loops.     

Efficient design of spatially symmetric Bragg gratings for add/drop multiplexers

A simple and fast numerical procedure is presented for designing spatially symmetric Bragg gratings with no need for iteratively solving the coupled mode equations. Using a unique relation between the phase and the amplitude of the reflection spectra valid for spatially symmetric gratings, the grating spectra are suitably optimized to fit given specifications. At the end of the design process an inverse-scattering algorithm determines the spatial structure of the corresponding Bragg grating. This method is particularly useful for the design of add/drop multiplexers, where symmetry can be a crucial prerequisite.     

光孤子在高斯变迹光栅中传输特性的数值分析

为了研究光纤光栅中布喇格孤子的传输特性,基于耦合波理论采用有限差分法在孤子传播速度与传输距离无关的条件下,数值模拟了布喇格孤子在高斯变迹光纤光栅中的传输以及孤子之间的相互作用,得到一些有意义的结果.结果表明,输入功率和初始脉宽等初始条件的不同将导致孤子峰值强度的周期变化;具有初始频率啁啾时布喇格孤子在传输过程中被展宽(正啁啾)或被窄化(负啁啾),并始终受到高斯变迹光栅的制约.当输入两个孤子时,它们之间的相互作用对其相对相位和相对振幅参量敏感.     

Microwave V-I transmission matrix formalism for the analysis of photonic circuits: application to fiber Bragg gratings

We propose the use of V-I matrices well known in microwave engineering to the analysis of photonic devices, especially those based on multilayer dielectrics. As an application we present a novel fast effective index method for the analysis of fiber Bragg gratings based on the use of V-I transmission matrices. It combines the exactitude of traditional effective index methods and the speed of coupled-mode methods.     

Microstructured fibre Bragg gratings: analysis and fabrication

A microstructured fibre Bragg grating that relies on a partial and localised etching of the cladding layer along the grating region is proposed. The main effect is the formation of defect states inside the bandgap depending on surrounding refractive index. This leads to the possibility of realising novel optoelectronic devices for sensing and telecommunication applications.     

Narrow-depressed cladding fiber design for minimization of claddingmode losses in azimuthally asymmetric fiber Bragg gratings

The cladding and radiation mode loss characteristics of photo-induced gratings written in fibers with a narrow-depressed inner cladding are compared to the properties of gratings written in matched clad, photosensitive clad, and wide-depressed cladding fibers under varying grating azimuthal asymmetry conditions. Fibers with narrow-depressed claddings are found to have lower cladding mode losses for small degrees of asymmetry than previously proposed fiber designs for cladding-mode reduction