Multilevel signaling for increasing the reach of 10 Gb/s lightwave systems
Multilevel signaling for increasing the reach of 10 Gb/s lightwave systems
复制标题
DOI：
10.1109/50.803016
复制
发表时间：
1999-11
影响因子：
4.7
通讯作者：
S. Walklin;J. Conradi
中科院分区：
文献类型：
--
作者：
S. Walklin;J. Conradi
研究了在标准单模光纤上工作的1550 nm光波系统中，以10 Gb/s速率工作的多进制、光调幅相移键控（AM-PSK）、多进制、M进制幅移键控（ASK）和多进制四进制信令方案。探索这些信号类型的前提是，它们将功率集中在更接近光载波的频率处，其中来自色散的光场的相位失真不太严重。研究了调制器啁啾、四进制ASK信号的最佳电平间距以及非零激光线宽下的调相-调幅（PM-AM）噪声转换问题。据发现，高阶多二进制信号不提供一个双二进制信号的色散容限的改善。4-ary ASK被证明在实验上将色散限制距离增加到225 km，并且通过仿真将色散限制距离增加到350 km，但是由于增加的电平数量和信号-自发拍频噪声的信号依赖性，以接收机灵敏度的a /spl sim/8 dB降级为代价。此外，4进制ASK信号的线宽要求小于1 MHz，以便在200-300 km上传输时最小化PM-AM相对强度噪声（RIN）的影响。
Polybinary, optical amplitude modulated phase shift keying (AM-PSK) polybinary, M-ary amplitude shift keying (ASK), and polyquaternary signaling schemes operating at 10 Gb/s are investigated in 1550-nm lightwave systems operating over standard, single-mode fiber. The premise for exploring these signal types is that they concentrate power at frequencies closer to the optical carrier where phase distortion of the optical field from chromatic dispersion is less severe. Issues such as modulator chirp, optimal level spacing in a 4-ary ASK signal, and phase modulated to amplitude modulated (PM-AM) noise conversion from a nonzero laser linewidth are studied. It is found that higher order polybinary signals do not offer an improvement in dispersion tolerance over a duobinary signal. 4-ary ASK is demonstrated to increase the dispersion-limited distance to 225 km experimentally and 350 km through simulation, but at the expense of a /spl sim/8 dB degradation in receiver sensitivity due to the increased number of levels and the signal dependence of signal-spontaneous beat noise. Furthermore, the linewidth requirement for a 4-ary ASK signal is less than 1 MHz in order to minimize the impact of PM-AM relative intensity noise (RIN) when transmitting over 200-300 km.