摘要
提出以改进型双二进制归零码(MD-RZ)信号作为标记,分别采用差分相移键控非归零码(NRZ-DPSK)信号和差分正交相移键控非归零码(NRZ-DQPSK)信号作为载荷进行正交调制的新方案.然后提出了一种从标记信号中提取和恢复时钟的简单方案.比较了背对背系统中2.5 Gbit/s的MD-RZ标记叠加到10 Gbit/s的NRZ-DPSK载荷和20 Gbit/s的NRZ-DQPSK载荷上的频谱特性,证明了MD-RZ标记占空比越大,光分组信号的频带利用率越高.采用传统的二进制强度调制-直接检测(IM-DD)系统的接收机检测得到了背对背系统中不同占空比的2.5 Gbit/s MD-RZ标记的眼图.结果表明,若采用色散补偿技术,两种光分组信号中的MD-RZ标记能够在长距离传输时克服接收端眼图的失真;当入纤功率值高于18 dBm时,占空比取值越大,MD-RZ标记的眼开度代价具有越高的传输鲁棒性.
Two novel orthogonal modulation schemes, in which a modified duobinary return-to-zero （MD-RZ） signal was generated as a label for optical switching network, were proposed. In one scheme, a non-return-to-zero differential phase shift keying （NRZ-DPSK） signal was generated as a payload, while in another scheme, a non-return-to-zero differential quadrature phase shift keying （NRZ-DQPSK） format payload was introduced. A simple method, in which the clock was extracted and recovered from label signals, was adopted. The spectra of two optical packet signals in the back-to-back label switching systems with 2.5 Gbit/s label and 10 Gbit/s payload, respectively, are compared. It is shown that the optical packet signal with a larger duty cycle label has higher spectral efficiency. In the back-to-back system, 2.5 Gbit/s MD-RZ labels with different duty cycles can be directly measured by a conventional binary intensity modulation direct detection （IM-DD） receiver. The MD-RZ labels of two optical packet signals can avoid the eye diagram distortion for long-distance transmission if the dispersion can be compensated. When the input power is beyond 18 dBm, the eye-opening penalty of MD-RZ label with a larger duty cycle is more robust in the label-detecting path.
出处
《中国激光》
EI
CAS
CSCD
北大核心
2008年第8期1201-1207,共7页
Chinese Journal of Lasers
基金
教育部新世纪优秀人才支持计划和高等学校博士学科点专项科研基金(20040532005)资助项目
关键词
光通信
标记交换
改进型双二进制归零码
相位调制器
双臂马赫-曾德尔调制器
optical communication label switching modified duobinary return-to-zero format phase modulator dual-arm Mach-Zehnder modulator
