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QD-SOA的动态仿真模型及其在光信号处理中的应用研究
【作者】 邢艳东；
【导师】 邱昆；
【作者基本信息】 电子科技大学 ， 光学工程， 2008， 硕士
【摘要】 在当前光网络的发展中,现有网络节点的光/电(电/光)转换的局限已经成为进一步扩大带宽的“瓶颈”,光分组交换可以解决这一问题。对光信号进行全光处理成为光分组交换研究中最关键的问题之一。量子点半导体光放大器(QD-SOA)与普通半导体光放大器(Bulk SOA)和量子阱半导体光放大器(QW-SOA)相比,具有低注入电流、低温度灵敏性、低线宽增强因子、高微分增益、高调制带宽、增益恢复时间快等优点,适合应用于全光信号处理。本文主要针对QD-SOA的动态仿真模型、放大特性及其在光分组交换网络中全光信号处理方面的应用进行研究,主要工作内容如下:1.根据QD-SOA的电子跃迁速率方程和光在QD-SOA中传播的光场方程,并采用牛顿法和四阶龙格-库塔法,建立了QD-SOA的动态仿真模型。2.利用建立的动态仿真模型,对QD-SOA的一些放大特性进行了数值仿真研究。包括最大模式增益、有源区的长度、以及基态与激发态的跃迁时间对输出光信号的消光比、脉宽和增益的影响,对影响因素进行了分析,提出了优化QD-SOA设计参数应注意的问题。3.分析了基于QD-SOA交叉增益调制(XGM)的波长转换器中,有源区长度L、基态与激发态之间的跃迁时间、信号光功率对输出光的消光比和脉冲宽度的影响。得出,增加有源区长度L、同时增加基态与激发态之间的跃迁时间、增加输入信号光功率都可以提高输出探测光的消光比、增加脉冲宽度的结论。4.提出了一种基于QD-SOA的XGM全光逻辑或非门方案。对方案的可行性进行了研究,输出的逻辑门没有码型效应,输出的消光比达到11dB,信号光速率可以达到400Gb/s。
【Abstract】 In the development of optical network, the limit of the O/E (E/O) conversion in the switching nodes has been the bottleneck of further improving the bandwidth of the network. Optical packet switching (OPS) can solve this problem. All-optical signal processing is one important part of the researches on OPS. Comparing to bulk Semiconductor Optical Amplifier (SOA) and Quantum-well Semiconductor Optical Amplifier (QW-SOA), Quantum dot Semiconductor Optical Amplifier(QD-SOA) have many unique advantages, such as lower threshold current, lower temperature sensitivity, lower linewidth enhancement factor, high differential gain, high modulation bandwith and faster gain recovery. Owing to so many advantages, QD-SOA is much more adapted to be used in the all-optical signal technology. The amplifying characteristics of QD-SOA, the numerical fragment model of QD-SOA and it’s applications in the all-optical signal processing related to OPS are investigated in this dissertation. The main research works are listed as follows:1. Based on the rate equations of the electron transition and the traveling-wave equation for signal wave in the QD-SOA, the numerical fragment model of QD-SOA is established. The Newton method is adopted to search the initial values of the model and the 4th order Runge-Kutta method is used to calculate the dynamic variation.2. The research activities involve the influences from the device-related parameters: the maximum modal gain, the length of the active layer, the transition time between the excited-state and ground-state. The characteristics of output pulse signal including extinction ratio, pulse width and gain have been chosen to the observing and comparing objects. The analysis in theory has also been provided to explain the simulation results.3. The study of wavelength conversion based on QD-SOA’s cross gain modulation (XGM) focus on the relationships between the extinction ratios, the converted pulse width and the length of active region, the input signal power, the electron transition time. The results show that the extinction ratio can be improved by increasing the length of active region, the input signal power or the electron transition time, but companying with the increase of output pulse width.4. A novel scheme of all-optical NOR gate based on the gain properties of QD-SOA is proposed.The feasibility of the scheme is investigated by simulation. No pattern effects is observed at the outputs of the NOR gate. The extinction of the output signal are higher than 11 dB and the processing rate reaches 400Gb/s.