【作者】 李岩；

【导师】 张以谟； 于晋龙； 周革；

【作者基本信息】 天津大学 ， 光学工程， 2007， 博士

【摘要】 由于高速光纤通信系统的色度色散(CD)容限非常低,在进行了长距离的固定CD补偿后,由于光网络中路径的动态选择、外界环境变化、光源的频率漂移及元件的老化等因素导致的动态变化的残余色散仍然会提高通信系统的误码率,动态色度色散(CD)补偿技术已经成为40Gb/s或更高速光纤通信系统中的一项关键技术。本文总结了当前存在的各种可调谐CD补偿技术和CD反馈信息提取技术,分析了高速光纤通信对动态CD补偿技术的要求。研究了高斯脉冲在色散介质中的传输。从理论上分析了光源谱宽和非线性效应对光脉冲在色散介质中传输的影响和CD对通信系统比特率和带宽的影响。完成了40Gb/s RZ码的动态CD补偿系统,包括利用DCF光纤和电光开关阵列实现的可调谐CD补偿模块、利用指定频带电功率检测法,基于微波功率放大器、窄带带通滤波器和功率检波器等实现反馈信息提取模块、基于数字信号处理器DSP实现的控制模块和采用自适应步长搜索方式实现的补偿算法。进行了基于SOA的SPM效应和XPM效应的40Gbit/s系统下可调谐CD补偿的理论分析,提出了基于SOA的XPM效应的连续动态CD补偿方案,进行了10Gbit/s系统中基于SOA的XPM效应的连续动态CD补偿实验,实现了小范围高精度的连续可调谐CD补偿。工作中的主要创新点:1.提出一种成本低廉,结构简单的检测给定频点处电功率值的CD反馈信息提取方法。从理论上推导出伪随机光脉冲序列的不同频点处电功率谱密度与系统累积色散值之间的关系式,分析了调制格式、被测频带带宽等因素对电功率法CD检测的影响。在40Gbit/s的RZ系统中实现的CD检测范围和检测精度分别为130ps/nm和3.25ps/nm/0.5dB。2.完成了基于DCF级联电光开关阵列和电功率检测技术的动态CD补偿系统,进行了40Gbit/s系统中的动态CD补偿实验,实现了82ps/nm的补偿范围和5ps/nm的补偿精度。补偿系统的最长响应时间为0.52s。3.提出基于SOA的连续动态CD补偿方案,从理论上分析了SOA注入电流、时钟光功率、时钟光与信号光之间的延时对CD补偿的影响,证明了该方案在40Gbit/s系统中可以补偿总范围大小为40ps/nm的正负色散。4.进行了10Gbit/s系统中基于SOA的XPM效应的连续可调谐CD补偿实验,实现了光源具有初始啁啾条件下的-40 ~ 60ps/nm范围内CD恶化波形的连续可调谐CD补偿。更多还原

【Abstract】 The tolerable chromatic dispersion (CD) for a very high-bit-rate transmission system (40Gbit/s or above) is very low. And even after the long distance static CD compensation, the BER of the communication system will increase due to the time-varying residual CD caused by factors like network reconfigurations, temperature fluctuation, laser’s wavelength drift and periodic repair/maintenance of fiber etc. Therefore the technology of dynamical CD compensation comes to be critical to the performance of very high-bit-rate transmission systems.In this dissertation, several reported tunable CD compensation and monitoring technologies are generalized and the needs for dynamical CD compensation of high-bit-rate transmission system are concluded. Theoretically, the transmission of Gaussian pulses in a CD media is analyzed including the influence caused by the initial chirp, laser line-width, and nonlinear effects. The influence of CD on the bit rate and bandwidth is also studied. A dynamical CD compensation sub-systems in 40Gbit/s RZ systems is established, which includes a tunable CD compensation module using DCFs cascaded with optical switch array, a CD monitoring module that based on narrow-band electrical power detecting and achieved by using devices such as microwave amplifiers, microwave filter and power detector, a controlling module with digital signal processor (DSP), and a controlling algorithm developed with adaptive searching. Tunable CD compensation method in 40Gbit/s systems based on the SPM and XPM effect of SOA is proposed and analyzed theoretically. A SOA based tunable CD compensation system is established in a 10Gbit/s system, which realized consecutive and small range tunable CD compensation.Major innovations of this dissertation:1. A cost-effective and simple CD monitoring method based on narrow-band electrical power detecting is proposed. A theoretical model is proposed and discussed focusing on the relationship between electrical power and CD at different frequency bands. The effects of factors such as modulation format, bandwidth and center frequency of microwave filter to the performance of this method are investigated. The detectable CD of 130ps/nm and resolution of 5.2ps/nm/dB are obtained experimentally within a frequency band centered at 12GHz in a 40Gbit/s system. 2. A dynamical CD compensation system is established based on DCFs cascaded with optical switch arrays and the electrical power detecting CD monitoring technique. The compensation range and resolution reaches 82ps/nm and 5ps/nm respectively. The maximal response time of the system is 0.52s.3. A consecutive tunable CD compensation method is proposed based on the XPM effect of SOA. The effects of tunable variable such as SOA inject current, optical power of clock pulse sequences and time delay between clock and signal sequences to CD compensation are analyzed theoretically and validated experimentally. The compensation range of 40ps/nm is indicated theoretically in 40Gbit/s systems.4. The 10Gbit/s consecutive tunable CD compensation based on SOA and DCF is tested,. A compensation range of -40 ~ 60ps/nm is achieved by using a serious chirped laser.更多还原