排序方式： 共有33条查询结果，搜索用时 0 毫秒
21.
Three group velocity dispersion (GVD) compensation schemes, i.e., the post-compensation, pre-compensation and hybrid-compensation schemes, are discussed with considering polarization mode dispersion (PMD). In the 10- and 40-Gbit/s non-return-zero (NRZ) on-off-key (OOK) systems, three physical factors, Kerr effect, GVD and PMD are considered. The numerical results show that, when the impact of PMD is taken into account, the GVD pre-compensation scheme performs best with more than 1 dB better of average eye-opening penalty (EOP) when input power is up to 10 dBm in the 10-Gbit/s system. However the GVD post-compensation scheme performs best for the case of 40 Gbit/s with input power less than 13 dBm, and GVD pre-compensation will be better if the input power increased beyond this range. The results are different from those already reported under the assumption that the impact of PMD is neglected. Therefore, the research in this paper provide a different insight into the system optimization when PMD, Kerr e 相似文献
22.
新闻英语具有语速快、涉及词汇量大、相关目的语国家社会文化背景繁杂等特点,尤其是新闻英语词汇特性突出.分析新闻英语的词汇特性,能帮助英语学习者更好地掌握新闻英语词汇的特征和运用规律,准确地了解新闻英语的信息内容. 相似文献
23.
以空调器压缩机气缸为例，介绍了如何用MDT和MasterCAM实现铸造模具的开发过程，对其几何外形造型设计和数控加工编程进行了详细的分析，实现了CAD／CAM技术在铸造模具中的应用。 相似文献
24.
We investigate the multilevel modulation for red-green-blue light emitting diode (RGB LED). A simple approach for extracting soft values from the modulation is proposed. The mapping way from bits to the modulated symbols for the multilevel modulation is also investigated. The modified modulation is obtained through the brute force. Based on the Monte Carlo simulations, the proposed approach and modified modulation are confirmed and better bit error rate (BER) performances are obtained. 相似文献
25.
单模光纤中偏振模色散的仿真模型 总被引：3，自引：3，他引：0
利用琼斯矩阵法研究了长单模光纤中偏振模色散的仿真模型.考虑到偏振模色散的随机性,该模型中单模光纤被看作是一系列短双折射光纤段的级联,相邻两段之间耦合角是随机的.研究结果表明,当短双折射光纤段等长时,偏振模色散呈现随波长周期性变化的特点;不符合实际情况.当短双折射光纤段不等长且服从高斯分布时,周期性逐渐消失;当其长度均方差为均值的20%,周期性完全消失.最后比较了偏振模色散的时域统计特性.取短双折射光纤段的长度服从高斯分布且均方差为均值的20%,偏振模色散的统计特性接近于实际分布.因此得出结论:为了正确估计偏振模色散的影响,在单模光纤的级联模型中,短双折射光纤段的长度应服从高斯分布,均方差为其均值的20%. 相似文献
26.
分数阶傅里叶变换是传统傅里叶变换的一种扩展形式,它能够在介于时域和频域之间的分数域内分析和处理信号。由于分数阶傅里叶变换的一些独特的性质,已经被广泛应用于解微分方程、量子力学、图像处理和信号处理当中。本文介绍分数阶傅里叶变换,综述其在滤波器、神经网络、图像处理和无线通信等领域的应用;结合本课题组近年来的工作成果,重点介绍了其在光通信领域中的典型应用;展望了分数阶傅里叶变换在光通信中的发展趋势。 相似文献
27.
光纤通信单信道速率持续向100 Gbit/s甚至更高发展,对测量仪器的带宽提出了更高的要求。由于电子瓶颈的限制,传统的电示波器极限带宽在70～90 GHz。目前能够测量100 Gbit/s光通信信号的电示波器技术难度和成本越来越高。为了突破电子瓶颈的限制,需要采用新的采样机理对超高速光通信信号或超宽带光信号进行测量。介绍了光域采样的基本原理和相应的光采样示波器及光采样示波器研发的进展。随着信道速率的不断提高,光纤链路的物理损伤对信号的影响越来越显著,如何监测光纤链路的物理损伤成为超高速光通信网需要解决的问题。基于对光物理层损伤的研究,提出了采用分数阶傅里叶变换测量光纤链路色散和非线性效应的方法,并对高速光纤通信链路的测量技术发展作了展望。 相似文献
28.
The temperature dependency of a 5-mol% MgO-doped periodically poled lithium niobate waveguide was investigated in this paper. We started with the temperature-dependent refractive index equation for the waveguide. Secondly, the temperature dependency of the second harmonic generation effect was experimentally researched under different temperatures and pump powers. The quasi-phase matched wavelengths, efficiency bandwidths and peak efficiencies of the waveguide were measured. The experimental results agreed with theoretical simulations, which are indispensable in the following all-optical sampling studies based on the cascaded second harmonic generation/difference-frequency generation process in the current device. 相似文献
29.
The operational parameters including the polarization controlling and the pump power in a nonlinear polarization rotation-based passively mode-locked fiber laser are studied in this paper.The carrier rate equations of the activated erbium-doped fiber are first employed together with the nonlinear Shro¨dinger equations to reveal the relation between the operational parameters and the output state of the passively mode-locked fiber laser.The numerical and experimental results demonstrate that the output state of the mode-locked laser varies with the polarization controlling and the pump power.The periodicity of the polarization controlling is observed.With given pump power,there exists a set of polarization controlling under which the ultra-short pulse can be generated.With given polarization controlling,the mode-locked state can be maintained generally except for some particular values of pump power.Three shapes of the output optical spectra from the fiber cavity can be identified when the pump power changes.The results in this paper provide a comprehensive insight into the operation of the nonlinear polarization rotation-based passively mode-locked fiber laser. 相似文献
30.
杨爱英 《江苏技术师范学院学报》2013,(5):47-49
印第安人作为北美最早的居民,创造了辉煌的印第安文学传统。当代美国印第安女作家路易丝·厄德里奇的《爱之药》探讨了回归印第安文化传统、追寻族裔文化身份的主题,这也是贯穿当代美国印第安作家作品的主题。《爱之药》分析了深受主流社会影响的当代印第安人困顿混乱的生活状态,为现代化进程中的印第安种族指出生存的必由之路,即维护族裔文化,回归部落传统,正视社会现实,融入多元文化。从印第安文学的复兴及其发展现状来看,美国印第安文学必将成为多元文化中重要的组成部分。 相似文献