随着光信息处理技术的发展, 基于光纤模式色散的光信息处理技术也开始得到了关注, 但是如何准确地激励出满足条件的模式一直限制着其应用。对于渐变多模光纤的模式激励已经有解析解, 阶跃多模光纤的模式激励没有解析解, 然而基于模式色散的光信息处理需要采用阶跃光纤来引入较大的模式色散。文中用Matlab数值仿真讨论阶跃光纤的模式激励。仿真结果表明, 改变高斯光束的入射条件, 例如偏移光束、倾斜光束、改变光束束腰半径, 均能得到不同的激励模式。最后, 通过实验验证了倾斜光束时的模式激励和模间色散的情况。

数值仿真研究了双曲正割、高斯(m=1)、超高斯脉冲(m=5)形皮秒脉冲泵浦在高非线性光纤正常色散区中时频域演化特性.计算结果表明,在峰值功率、泵浦光纤参数相同的条件下,泵浦脉冲前(后)沿陡峭程度影响频谱展宽宽度,脉冲前后沿越陡峭,生成的超连续谱带宽越宽;脉冲前(后)沿的拖尾部影响展宽频谱的平坦性,脉冲前后沿拖尾越小,生成的超连续谱频带平坦度越高.泵浦脉冲中是否含有啁啾对生成的超连续谱的带宽和平坦性影响微弱.脉冲前(后)沿拖尾小或者陡峭的脉冲在高非线性光纤正常色散区可以产生带宽平坦的超连续谱.

A novel approach for the implementation of microwave photonic filter with positive and negative coefficients based on an unbalanced Mach-Zehnder modulator (MZM) is proposed. In the proposed filter, a microwave signal to be filtered is applied to an unbalanced MZM. Thanks to the unbalance between the two arms of the modulator, a π phase shift is obtained by adjusting the wavelength interval between the adjacent wavelengths, which leads to the generation of the positive and negative coefficients. The theoretical fundamentals of the design are described, which show that the required unbalanced MZM in the scheme can be well fabricated by the current technology, and the required other components, including the wavelength multiplexer, are also commercially available devices. An eight-tap microwave photonic filter with positive and negative coefficients is demonstrated. The tunability and reconfigurability of the eight-tap microwave photonic filter are also investigated to verify our approach.

An improved multiplier-free feed-forward carrier phase estimation algorithm is proposed for dual-polarization quadrature- phase-shift-keying (DP-QPSK) with coherent detection. The bit error rate (BER) performance, block length effect and linewidth tolerance of the proposed algorithm are evaluated for a 112 Gbit/s DP-QPSK system. A linewidth symbol duration product of 2.9×10^-4is demonstrated for 1 dB optical signal-to-noise-ratio (OSNR) penalty at BER of 10^-3for the proposed algorithm. The hardware complexity of the proposed multiplier-free algorithm is demonstrated to be much lower than that of the 4th power algorithm.

详细研究了单控制脉冲 TOAD(terahertz optical asymmetric demultiplexer)结构开关窗口的非对称缺陷及其产生机理。通摘过理论分析和 optisystem仿真证实了双控制脉冲 TOAD结构能够很好地解决单控制脉冲 TOAD结构的开关窗口缺陷。仿真结果显示, 双控制脉冲 TOAD获得了波形对称、对比度更高的开关窗, 详细解释了仿真中出现的双峰现象。

提出了一种能够同时对高速光时分复用技术信号解复用与时钟提取的光电反馈环单元.在接收端，采用光电反馈环单元，信号单次通过即可同时完成160 Gb/s到10 Gb/s的解复用与时钟提取：两级电吸收调制器级联工作方式缩减了采样窗口宽度，满足了解复用小于6.25 ps超窄采样窗口的要求；而闭合环路的锁相同步工作方式，使所提取的时钟信号抖动(Jitter RMS)由2.4 ps降至450 fs.基于该结构，实验上成功实现了无误码的100 km 160 Gb/s光时分复用技术传输及传输后无误码地解复用与时钟提取，功率代价小于3 dB.

第一次把DIRECT算法用于偏振模色散补偿中作为反馈控制算法的第一部分，来寻找初始的全局最优解。用著名的Hartman6函数的返回值模拟偏振度的测量值，给出了DIRECT算法对Hartman6函数全局最优解的寻找过程，通过与其它几种全局最优化算法的比较，对DIRECT算法进行了初步的评价。