光差分相移键控调制格式原理

DPSK（差分相移键控）调制格式是一种将信号调制到相位信息上的调制方式。与传统的OOK调制方式相比，DPSK最显著的优点是在达到相同的误码率（BER）时，对光信噪比的要求低了3dB。本文详细讲述了DPSK信号的产生、接收方式及特性。     

基于马赫-曾德尔调制器的先进调制格式的产生

提出了一种基于差分马赫-曾德尔调制器(MZM)产生80 Gbit/s高速率差分相移键控归零码(RZ-DPSK)、差分相移键控载波抑制归零码(CSRZ-DPSK)、差分正交相移键控归零码(RZ-DQPSK)、差分正交相移键控载波抑制归零码(CSRZ-DQPSK)的新方法.在采用两个差分MZM级联产生数据速率为80 Gbit/s的RZ/CSRZ-DPSK光信号的基础上,仅需增加一个双驱动MZM,就可以产生RZ/CSRZ-DQPSK信号,说明提出的方法有一定的扩展性,并简化了高速RZ/CSRZ-DQPSK光信号的产生过程.对产生的80 Gbit/s RZ/CSRZ-DPSK和RZ/CSRZ-DQPSK信号进行的仿真结果表明,CSRZ-DPSK信号比RZ-DPSK信号的频谱结构更加紧凑,差分正交相移键控(DQPSK)光谱形状与差分相移键控(DPSK)相同,只是由于RZ/CSRZ-DQPSK在码元速率下传输数据,得到的光谱在频域被压缩.     

光MDPSK通用调制解调结构构建及仿真

新型相位调制格式技术能够有效地减少光传输损伤,是光传输系统中的重要技术。从理论上分析了光MDPSK(M进制差分相移键控)的调制解调原理,构建了通用的调制解调结构,并首次推导出MDPSK的通式和解调公式,最后以基于CSRZ(载波抑制归零,占空比为67%)码的DQPSK(差分正交相移键控)、8DPSK(3阶差分相移键控)和16DPSK(4阶差分相移键控)为例,用MATLAB软件仿真得到了其调制后的频谱图和解调后的眼图。仿真结果表明,随着级数的增加,MDPSK调制格式的频谱宽度会逐渐变窄,且解调后的眼图也令人满意。     

晶体型差分相移键控格式解调器

介绍了利用偏振光干涉原理的晶体型DPSK与DQPSK解调器,理论推导结果表明,这种晶体型解调器能够实现与普通解调器同样的功能;更进一步地,通过旋转一个四分之一波片,该器件可以实现在DPSK与DQPSK解调器功能之间的切换。实际研制了该解调器,其PDFS在整个C波段小于0．4GHz,响应时间小于50ms,各项指标均达到了商用化的水平。     

差分相移键控的非归零到归零格式转换研究

提出了一种全新的基于相位-强度混合调制和色散补偿的光差分相移键控(DPSK)信号的非归零(NRZ)到归零(RZ)格式转换器,理论分析了转换器参数对转换的影响,数值研究了恶化条件下的10 Gb/s的NRZ-DPSK到RZ-DPSK的格式转换。实验展示了10 Gb/s的DPSK信号格式转换及解调后的误码性能。计算结果表明,通过设计转换器参数可获得低占空比RZ-DPSK信号,且转换后信号质量较高。实验结果表明格式转换功率代价较低,转换后RZ-DPSK信号时间抖动较原NRZ-DPSK信号减小。该格式转换器还适合光四相差分相移键控(DQPSK)的非归零到归零格式转换及多波长操作。     

高速光DQPSK调制中预编码器的实现

提出了高速光差分相移键控(DQPSK)调制中预编码的实现方法.该方法通过研究光DQPSK的调制方式和接收模型,得出预编码器的编码特性图,利用卡诺图化简推导出DQPSK预编码器逻辑表达式.使用该方法,可以根据光DQPSK的调制方式和接收模型,设计相应的预编码器.     

光DQPSK调制格式原理及仿真

文章简单介绍了光差分正交相移键控(DQPSK)调制格式的调制和解调方式,对光DQPSK的预编码也进行了必要的说明.使用软件Matlab构建了光DQPSK背靠背系统,得到了不同的DQPSK调制的频谱图和眼图,并对仿真结果进行了验证,就NRZ-DQPSK和RZ33-DQPSK的差异进行了比较.     

RZ、CSRZ码在CBG色散补偿系统中的传输

全部利用线性啁啾光纤布拉格光栅（CBG）作色散补偿模块和在线通道滤波顺，在2500km超长距离的G．652光纤上实现10Ghps归零码（RZ）、载波抑制归零码（CSRZ）光信号的无电中继传输，并在2080km和2560km处分别对2种信号的传输性能进行了测试。CSRZ在上述2处的功率代价分别为～1dBm和～3dBm（BER-10^12，PRBS=10^23-1），RZ的功率代价分别为～3dBm和～5dBm，验证了在相同系统平台下CSRZ光信号比RZ光信号有更好的性能.     

基于CSRZ码的多进制相位调制格式传输性能研究

将抑制载波归零(CSRZ)码与先进的多进制调制技术结合应用于40Gb/s的光通信系统中,分析了其抗色散和抗非线性能力。仿真结果表明,随着进制的提高,信号的抗色散能力增强,抗非线性性能变差。在此基础上,还研究了采用3种不同的色散补偿方式时,多进制相位调制格式的Q值随入纤光功率变化的变化情况。     

40Gb/sWDM系统中RZ&NRZ调制格式的性能比较

利用数值计算的方法对40G WDM系统进行了仿真.在考虑了光纤群速度色散(GVD)、三阶色散(TOD)、自相位调制(SPM)、交叉相位调制(XPM)、四波混频(FWM)和偏振模色散(PMD)的前提下,通过对比眼图和Q因子,对归零码(RZ)和非归零码(NRZ)调制格式的传输性能进行了研究.     

DPSK/FSK Hybrid Modulation Format and Analysis of Its Nonlinear Performance

We propose a novel hybrid modulation format-differential phase shift keying with frequency shift keying labeling for optical label switching. A modulation technique based on a dual-parallel Mach-Zehnder modulator and a label erasing scheme are presented. The tolerance of the new format to intrachannel four-wave mixing at high speeds is studied analytically and through simulations, which show robustness to nonlinear impairments.     

光DQPSK调制原理

光DQPSK作为一种新型光纤通信系统的调制格式,具有非常窄的频谱宽度,近似恒定的包络特性,能有效抑制各类光纤的非线性效应。从它的基本原理推导入手,分析了光DQPSK编码,调制和解码过程,提出了实现光DQPSK调制的两种方式和接收模型。     

Optical Systems With High-Order DPSK and Star QAM Modulation Based on Interferometric Direct Detection

Increased interest in novel modulation formats for optical transmission has come up in recent years. Receivers with interferometric direct detection can be used to detect arbitrary modulation formats with differentially encoded phases as differential phase-shift keying (DPSK) and differentially phase-encoded star-shaped quadrature amplitude modulation (Star QAM). In this paper, two novel 16-ary modulation formats, which are the 16 DPSK and the Star 16 QAM (ASK-8 DPSK), are characterized for optical transmission for the first time. To be able to identify clear performance tendencies for high-order optical modulation, the novel formats are compared to a wide range of already investigated formats by conducting comprehensive calculations in a uniform simulation environment. The influence of different transmitter structures and decision schemes is considered, and all the systems are characterized with respect to the optical signal-to-noise ratio requirements, dispersion tolerance, and self-phase-modulation (SPM) performance for nonreturn-to-zero (NRZ) and RZ pulse shapes. Moreover, an inherent problem of Star QAM transmission concerning SPM is illustrated, and compensation techniques are examined. The results give a substantial insight into the properties of high-order optical modulation formats.     

Optical Phase Add–Drop for Format Conversion Between DQPSK and DPSK and its Application in Optical Label Switching Systems

We propose and experimentally demonstrate an optical phase “add–drop” scheme to enable the format conversion between a 20-Gb/s differential quadrature phase-shift keying (DQPSK) and 10-Gb/s differential phase-shift keying. Meanwhile, the incoming DQPSK could be directly forwarded to another wavelength through the proposed optical phase “drop” scheme, which is implemented by four-wave-mixing effect in highly nonlinear fiber. By orthogonally encoding the label and payload of the optical packet on the in-phase ( $I$) and quadrature ( $ Q $) components of DQPSK, the proposed scheme could be applied in the optical label switching networks. The label erasing and rewriting of optical packets can be achieved through the proposed optical phase “drop” and “add” schemes, respectively.      

System Performance of High-Order Optical DPSK and Star QAM Modulation for Direct Detection Analyzed by Semi-Analytical BER Estimation

Recently, higher order modulation formats are intensively investigated to further increase spectral efficiency for building next generation optical transport networks. Direct detection receivers are capable of detecting arbitrary modulation formats with differentially encoded phases such as differentially phase shift keying (DPSK) and star shaped quadrature amplitude modulation (Star QAM) formats. In an earlier publication of the authors (M. Seimetz , “Optical systems with high-order DPSK and star QAM modulation based on interferometric direct detection,” J. Lightw. Technol. , vol. 25, no. 6, pp. 1515–1530, Jun. 2007) a system analysis was performed where performance was mainly characterized by eye opening penalties. Here, these investigations are extended. A tool for semi-analytical BER estimation is developed allowing to calculate the BER down to small values such as $10^{-9}$ for a wide range of modulation formats, as well as for different receiver structures. Using this module, the back-to-back OSNR requirements are calculated. CD and SPM tolerances are characterized by optical signal-to-noise ratio (OSNR) penalties at ${hbox {BER}} = 10^{-9}$ . As far as the authors know, this is the first analysis of the transmission characteristics of optical 16DPSK and Star 16QAM based on the BER. Moreover, further novel aspects such as optimization of the optical and electrical receiver filter bandwidths are investigated.      

3DPSK信号调制与解调研究

本文论述了三进制差分相位键控信号的调制与解调技术,在研究3DPSK信号产生的基础上,提出了一种延迟解调技术。     

基于FPGA的全数字化2DPSK调制系统的实现

近年来,无线通信由于具有覆盖地域广、通信距离远、通信容量大、传输质量好和具有多址联接能力等优点,己成为现代信息社会的一种重要通信手段。数字调制技术作为这个领域中极为重要的一个方面,也得到了迅速发展。目前在数字通信中,人们广泛采用2DPSK调制解调技术。文中介绍了一种以A1tera公司的ACEX1K系列芯片中的EPIK30TC144—3为主控芯片。并通过MAX＋PLUSII开发工具和Verilog HDL语言编程实现一种全数字的调制系统——2DPSK。     

All-Optical Asynchronous Serial-to-Parallel Converter Circuit for DPSK Optical Packets

We propose a novel asynchronous all-optical circuit for extraction and serial-to-parallel conversion of label bits from differential phase-shift keying (DPSK) packets. The circuit requires only two optical switches regardless of the number of bits to be extracted and parallelized from the packet. Experimental evidence of practical use of the circuit to four bit labels at 10 Gb/s is provided. The circuit is scalable with the number of bits, operates at low input power, and is suitable for photonic integration. The asynchronous nature of the circuit allows us to efficiently extract/read one specific label field of variable length without processing the entire label, leading to a simplified architecture of the label processing circuit     

2DPSK光纤通信系统的误码特性分析

通过把噪声展成KLSE级数的方法,得到了2DPSK光纤通信系统接收端噪声以及抽样判决变量的概率分布特性.在此基础上分析了2DPSK光纤通信系统的抗噪声特性.经过蒙特卡洛仿真验证可知,把KLSE方法用于2DPSK光纤通信系统是完全可行的.分析了2DPSK光纤通信和OOK光纤通信系统的抗噪性能,得出在同样误码率情况下2DPSK系统所需信噪比的值比OOK系统低3 dB的结论.