文章仿真研究了两种改进型光双二进制调制格式。首先对比分析了产生两种改进型光双二进制调制格式的发射机结构及两种调制格式的码型和频谱特性, 随后进行了系统的传输性能仿真。仿真结果表明: 当残留色散较大时, 改进Ⅱ型光双二进制调制格式性能较为优异; 而在-13.2～2.8 dBm入纤光功率范围内, 与改进Ⅱ型光双二进制和NRZ (非归零) 码调制格式相比, 改进Ⅰ型光双二进制的Q值最高, 抗非线性效应能力最强。

This paper studies by simulation two kinds of modulation formats for modified optical duobinary. It first compares and analyzes the structures of the transmitters that generate these formats, and their code type and spectrum characteristics. Afterwards, it simulates the system transmission performances. The results show that when the residual dispersion is large, the modified type Ⅱ optical duobinary modulation format has better performance. However, within the incident optical power range of -13.2 ～ 2.8 dBm, the modified type I optical duobinary modulation format has the highest Q value and hence the strongest resistance to nonlinear effects compared with the modified type Ⅱ optical duobinary and NRZ modulation formats.