折射率调制深度误差对切趾啁啾光纤光栅特性的影响

从耦合模方程出发,用一种矩阵方法分析了折射率调制深度误差对切趾啁啾布拉格光纤光栅传输特性的影响。结果表明：折射率调制深度误差的分布频率越高,光栅传输特性受到的危害越小;误差平均幅值越高,光栅传输特性的劣化程度越大。因此,在光栅的制作过程中,应注意避免和减小高幅值误差,并注意减少低空间频率分布的误差。     

折射率调制深度误差对切趾啁啾光纤光栅特性的影响

从耦合模方程出发,用一种矩阵方法分析了折射率调制深度误差对切趾啁啾布拉格光纤光栅传输特性的影响.结果表明:折射率调制深度误差的分布频率越高,光栅传输特性受到的危害越小;误差平均幅值越高,光栅传输特性的劣化程度越大.因此,在光栅的制作过程中,应注意避免和减小高幅值误差,并注意减少低空间频率分布的误差.     

Highly sensitive distributed liquid-droplet sensor based on evanescent-wave linearly chirped fiber Bragg grating

We propose a highly-sensitive distributed addressable liquid-droplet sensor based on an evanescent-wave linearly chirped fiber Bragg grating (LCFBG). Due to liquid-droplet-induced increase of the localized effective refractive index, a transmission window is generated within the original reflection stopband of LCFBG. Utilizing the spatial encoding feature of Bragg wavelength in LCFBG and spectrum properties of the created passband, both numerical and experimental results demonstrate that the position, size, and refractive index information of multiple distributed discrete liquid-droplets can be detected simultaneously.     

拉锥型啁啾光纤光栅滤波器的研究

本文主要对拉锥型啁啾光纤光栅滤波器进行详细的理论分析和实验研究. 结合传输矩阵法, 谐振理论和耦合模理论, 深入细致地分析了啁啾光纤光栅自身参数 (光栅长度, 折射率调制幅度, 啁啾系数), 拉锥参数和锥区损耗对拉锥型啁啾光纤光栅滤波器透射谱的影响, 并研究拉锥对啁啾光纤光栅各波长反射率影响. 在此基础之上进行相应的数值仿真及实验验证, 数值仿真与实验结果基本一致. 关键词： 光栅拉锥 啁啾光栅 传输矩阵法 滤波器     

Fabrication of high quality chirped fiber Bragg grating by establishing strain gradient

To fabricate chirped fiber Bragg grating (CFBG) with high reflectivity and accurately controlled chirp profile with low cost, we develop the CFBG fabrication technique based on strain gradient: fabricating CFBG using fabricated fiber Bragg grating (FBG) by establishing strain gradient along the length of grating. We theoretically analyze the form of such CFBGs, and study the characteristics of gratings using piecewise-uniform approach. It is shown that increasing UV-induced index change or the length of the grating or both are the efficient ways to obtain high quality CFBG with high reflectivity and good reflection spectrum. The dispersion of this grating is decided by and varies inversely with the slope of the strain gradient along the length of the grating, not decided by UV-induced index change or by the length of grating. One can control the dispersion and the chirp profile by adjusting the slope of the strain gradient. Based on the theoretical analysis, we have fabricated CFBG whose reflectivity is maintained at 100% in a large range of strain gradients.     

Code synchronization based on lumped time-delay compensation scheme with a linearly chirped fiber Bragg grating in all-optical analog-to-digital conversion

We propose a novel lumped time-delay compensation scheme for all-optical analog-to-digital conversion based on soliton self-frequency shift and optical interconnection techniques. A linearly chirped fiber Bragg grating is optimally designed and used to compensate for the entire time-delays of the quantized pulses precisely. Simulation results show that the compensated coding pulses are well synchronized with a time difference less than 3.3 ps, which can support a maximum sampling rate of 151.52 GSa/s. The proposed scheme can efficiently reduce the structure complexity and cost of all-optical analog-to-digital conversion compared to the previous schemes with multiple optical time-delay lines.     

双带通啁啾光纤光栅光谱特性仿真及分析

针对啁啾光纤光栅的带通滤波特性,设计了纤芯/包层复合结构的啁啾光纤光栅滤波器.基于光纤耦合模和传输矩阵理论及坐标变换方法,对其光谱特性进行仿真分析,验证了该光栅的双带通滤波特性;对周期为536、537、538nm,长度为8、10、12mm,折射率调试深度为0.0002、0.0003、0.0004,啁啾系数为0.05、0...     

光栅不理想特性对不同调制码型的光传输系统的影响

分析了光纤光栅不理想特性的产生机理，对以啁啾光纤光栅为色散补偿器的10Gb/s光传输系统中，啁啾光纤光栅的不理想特性包括群时延纹波、反射纹波及光栅通带带宽对采用归零码(RZ)、非归零码(NRZ)以及载波抑制归零码(CSRZ)三种调制格式传输系统性能的影响进行了详细的数值分析和比较. 同时进行了基于光纤光栅色散补偿的1500km无误码传输实验，通过对啁啾光纤光栅由于不理想特性的差别而导致对实际传输系统不同信道性能影响的比较，进一步验证了仿真分析的正确性. 关键词： 光传输 啁啾光纤光栅 不理想特性 调制码型     

A novel adjustable PMD compensator based on a tapered high-birefringence linearly chirped fiber Bragg grating

A novel solution for polarization mode dispersion (PMD) compensation is proposed by applying tension on a tapered high-birefringence linearly chirped fiber Bragg grating. The compensated differential group delay changes with the applied tension, for its cross-sectional area varies nonlinearly along the grating. Its performance as PMD compensator for short pulses fiber-optical transmission system and 10 Gb/s NRZ fiber-optical transmission system is demonstrated experimentally.     

啁啾莫尔光纤光栅特性的研究

较全面地分析了啁啾莫尔光纤光栅的特性。介绍了啁啾莫尔光纤光栅的发展与应用前景。提出了利用薄膜传输矩阵的方法来计算光纤光栅 ,这种算法将光栅视为多层均匀薄膜的叠加 ,利用传输矩阵计算光栅特性 ,并将这种算法与其它相关算法进行了比较。作为一种滤波器 ,啁啾莫尔光纤光栅的透射特性尤为重要 ,针对这种光纤光栅的长度、啁啾量及相移等重要参数计算了光栅的透射率变化 ,并对结果进行了优化数值分析 ,得出了它们之间的关系     

一种新型的利用重构等效啁啾超结构光纤光栅消啁啾技术研究

提出了一种利用重构等效啁啾超结构光纤光栅对啁啾光脉冲进行频域消啁啾和时域脉宽压缩的方法.由于重构等效啁啾技术可实现任意物理可实现滤波特性的光纤光栅,因此所提出的新型消啁啾方法可以针对任意啁啾模型的脉冲.仿真结果表明,对于脉宽为20 ps,啁啾系数为-5,啁啾模型为线性、高斯型、洛仑兹型的啁啾高斯脉冲,其被消啁啾后时间带宽积分别由初始的225,265,250下降到0458,0708,0731,脉宽压缩效果明显.针对商业软件给出的增益开关分布反馈半导体激光器输出光脉冲的模型,实际制作相应的重构等效 关键词： 重构等效啁啾 光纤光栅 啁啾 增益开关分布反馈半导体激光器     

啁啾相移光纤光栅分布式应变与应变点精确定位传感研究

利用啁啾相移光纤光栅狭缝的中心波长对应变点和应变量的波长敏感性,实现应变与应变点精确定位的传感.当啁啾光纤光栅上的某一位置产生微应变时,该应变点会产生相移,其频谱则会出现一个与之对应的狭缝,且狭缝的深度和中心波长与应变的大小和位置相关.当串接不同中心波长的啁啾光纤光栅后,即可实现一定范围内的分布式应变与应变点精确定位检测.本文通过V-I传输矩阵法建立了狭缝深度和中心波长关于应变量和应变位置的理论模型,分析结果表明理论上可以实现微米量级的精确定位.搭建了级联啁啾相移光纤光栅的分布式应变传感装置,实验获得的最大应变灵敏度为0.19 pm/με.该精确定位传感装置在先进制造、精密加工、航空航天、铁路系统等高新技术领域具有重要的应用前景.     

简支梁调谐啁啾光纤光栅的实验研究

利用有机玻璃块和螺旋测微器组成的简支梁系统调谐线性啁啾光纤光栅,将中心波长为1548.6nm、3dB带宽为0.43nm、长为25mm的均匀Bragg光纤光栅按一定角度牢牢的固定在一块长为90mm,宽为10mm,高为5.2mm的有机玻璃块中,再用螺旋测微仪在有机玻璃的中心位置向下施加压力,使简支梁及其中的光纤光栅变形,成为可调谐的啁啾光纤光栅。实验结果表明啁啾光纤光栅反射谱宽与简支梁弯曲量成线性关系,当简支梁最大弯曲量为1.2mm时光纤光栅反射谱展宽了4.02nm,而反射中心波长基本不变,该实验装置可以用于光控相控阵雷达天线的实时延迟线和光纤色散补偿。     

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     

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     

Chirped Bragg光纤光栅的优化设计与优化指数

根据线性ChirpedBragg光纤光栅的一般原理 ,探讨了不同啁啾系数 ,准高斯耦合函数对Bragg反射光栅的反射率及色散补偿特性的响应。结果表明 :增大啁啾系数以及选取适当的准高斯耦合函数 ,在保证反射率较大的情况下 ,能有效地改善色散补偿特性。通过引入微波领域的“优化指数”这一概念 ,量化了色散补偿器的补偿能力。     

300 W线偏振飞秒全光纤啁啾脉冲放大系统

报道了高平均功率的线偏振啁啾脉冲放大系统。该系统包括全光纤结构的多级放大器以及透射光栅脉冲压缩器。压缩前, 实现了近衍射极限光束输出, 平均功率425 W, 光光效率81%, 消光比约13 dB;压缩后, 获得了平均功率300 W、脉宽315 fs、峰值功率12 MW的激光脉冲, 为目前报道的最高平均功率的线偏振光纤啁啾脉冲放大系统。     

线性啁啾光纤光栅色散补偿性能的数值分析

对线性啁啾光纤光栅的色散补偿性能进行了数值分析。结果表明 ,啁啾光栅时延曲线的纹波大小和线性度是影响其色散补偿性能的两个重要因素。对高斯型耦合系数分布光栅而言 ,更长的光栅将具有更佳的色散补偿性能     

A phase-shifted linearly chirped fiber Bragg grating with tunable bandwidth

We demonstrate a new method to broaden and adjust the transmission bandwidth of a phase-shifted linearly chirped fiber Bragg grating (PS-LCFBG) after its fabrication. A movable thermal head is used to heat the PS-LCFBG at a small contact point. The original ultra-narrow transmission bandwidth of the PS-LCFBG can be broadened due to both the presence of the passband peak caused by the thermally-induced temporary phase shift and the passband caused by the thermally-induced local Bragg wavelength shift. The transmission bandwidth of the new passband peak can be adjusted by changing the position of the thermal head. The transmission bandwidth of the PS-LCFBG can be broadened from <10 pm to 0.16 nm, and can be tuned from 0.16 to 1.05 nm.     

Improving the performance of chirped fiber grating with cladding being etched as sinusoidal function

A new grating structure of cladding being etched as sinusoidal function along the grating length is introduced to improve their performance. When a tension is applied to it, the fiber grating not only exhibits a flattop spectrum with steep edges and high reflectivity, but also has a smoothly time delay curve. The bandwidth utilization defined as the ratio of −1:−30 could be achieved a larger value (>0.90). The −3 dB bandwidth and the bandwidth utilization could be tunable with the increment of tension applied to the grating and the linearly chirped modulus.