基于马赫-曾德尔调制器的多种调制格式微波信号的光学生成研究

提出了一种基于马赫-曾德尔调制器(MZM)的 多种调制格式微波信号的光学一体化生成方案。 在本文方案中,微波信号和编码矩形波信号经合路器同时输入到MZM中,通过合理设置编码 信号的幅值使 MZM能够工作在其传输曲线的不同传输点,分别实现了频移键控(FSK)、二进制相移键控(BPSK)和 二倍频BPSK微波信号一体化生成。本文方案仅需要1个MZM而不需要额外加电的或光的选频器 件, 因此具有结构简单、可大范围调谐的优势。特别的,本文方案还可以产生二倍频的BPSK微波 信号,从 而使能够满足更高频的应用需求。在仿真和实验中,分别得到10/20 GHz的FSK、10GHz的BPSK 微波信号,同时产生了20GHz的二倍频BPSK微波信号,有效验证了本 文方案的可行性。     

多种调制格式微波信号的光学产生方案

提出了一种基于偏振调制器（PolM）和Sagnac环级联的多调制格式微波信号的光学产生方案。理论分析了PolM在基带编码信号的驱动下产生偏振键控（PolSK）信号的基本原理,Sagnac环中嵌有两个马赫增德尔调制器（MZM）,分别对顺时针和逆时针传输的PolSK信号进行独立调制。通过合理调整两个MZM的驱动信号,实现了幅移键控（ASK）、频移键控（FSK）和相移键控（PSK）微波信号的产生。在仿真实验中,产生了比特率为2 Gbit/s的40 GHz ASK信号、20/40 GHz FSK信号和20 GHz PSK信号,同时验证了比特率和载波频率的宽带可调谐性。Sagnac环结构提升了系统的稳定性,并且针对每种调制格式的微波信号,在不改变链路结构的情况下其比特率和载波频率都可以通过控制基带编码信号和MZM的射频驱动来进行独立且灵活的调谐。     

STOLAS: switching technologies for optically labeled signals

GMPLS-based labeled optical burst switching (LOBS) networks are being considered as the next-generation optical Internet. GMPLS includes wavelength switching next to label and fiber (space) switching. We present a new concept of optically labeling bursts of packets suitable for LOBS networks supported by GMPLS. It is based on angle modulation, which enables control information to modulate the phase or frequency of the optical carrier, while payload data are transmitted via intensity modulation (IM). In particular, the optical label is orthogonally modulated, with respect to the payload, using either frequency shift keying or differential phase shift keying. We present a performance analysis of the modulation schemes by means of simulations where the influence of the payload IM extinction ratio and laser linewidth are investigated. In addition, the transmission performance of an IM/FSK combined modulated signal is experimentally validated at 10 Gb/s, demonstrating at the same time an FSK label swapping operation. Finally, a suitable optical label-controlled switch design is proposed that takes advantage of these novel labeling techniques, and efficiently combines widely tunable, fast switching lasers and SOA-MZI wavelength converters with an arrayed waveguide grating router.     

改进型双二进制归零码信号在标记交换系统中的新应用

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.     

ASK／FSK光标记交换系统中的OBPF谱均衡法

基于幅移键控／频移键控（ASK／FSK）正交调制光标记交换（0LS）系统工作原理,提出了一种利用光带通滤波器（OBPF）对FSK标记进行谱均衡的方法,从而有效改善ASK净荷接收灵敏度。利用仿真,对40Gb／sASK／FSK正交调制OLS系统,在使用3种不同类型OBPF进行谱均衡时的传输性能进行了验证与比较分析。结果表明...     

Investigation on the combined orthogonal FSK/ASK labeled signal based on cross gain modulation in a SOA

An optical frequency shift keying(FSK) transmitter performed by the cross gain modulation(XGM) in a semiconductor optical amplifier(SOA) is used in an optical label switching(OLS) system with 622 Mbit/s FSK label and 10 Gbit/s amplitude shift keying(ASK) payload.The key parameters in this system are optimized to achieve the best performance of FSK/ASK signal,including the input power of LD,the extinction ratio(ER) of the control light and that of the ASK payload.Besides,the transmission performance of ASK p...     

A novel orthogonal modulation format of D8PSK/ASK with differential bi-phase encoding and its application in a label switching optical network

The principle of a novel orthogonal modulation format of differential 8-level phase-shift keying amplitude-shift keying (D8PSK/ASK) with differential bi-phase encoding (DBC) is introduced. Based on it, an optical labeling scheme, in which the payload is 100 Gbit/s D8PSK signal and the label is 10 Gbit/s DBC-ASK signal, is proposed and simulated. The results are compared with other current schemes, and the effects of transmission range, modulation extinction ratio (ER) and received power on system performance are analyzed, respectively. The results show that the spectrum efficiency and bit error rate (BER) are improved greatly, and when the modulation ER is increased to 11 dB, the balanced performance between the payload and label is achieved.     

一种基于D8PSK／ASK正交调制的新型光标记方案研究

深入研究了差分八相移键控（I）8PSK）j幅移键控（AsK）正交调制格式的机理,提出了一种基于D8PsKjASK正交调制的新型光标记方案,利用D8PSK作为载荷的调制方式,ASK作为标记的调制方式,仿真实现了载荷120Gb／s、标记10Gb／s的传输速率。分析了信号的消光比（ER）对误码率（BER）的影响,仿真结果表明...     

An optical IM/FSK coding technique for the implementation of a label-controlled arrayed waveguide packet router

In this paper, we present a new concept of optical packet/burst switching suitable for generalized multiprotocol label switched (GMPLS)-based optical networks. In such networks, optical labeled switched paths are being established in a similar way as label-switched paths in MPLS. We use a wavelength label as well as an orthogonally modulated label, with respect to the payload modulation format, and which is encoded using either frequency-shift keying (FSK) or differential phase-shift keying (DPSK). Wavelength is used for switching in the node, whereas the orthogonal label defines the label-switched path. We present both simulation and experimental results to assess transmission performance of the proposed combined modulation scheme. In addition, we propose a suitable optical node architecture that can take advantage of this stacked label concept. Toward this, we use widely tunable wavelength converters to efficiently route IM/FSK (or IM/DPSK) optically labeled packets in an arrayed-waveguide grating (AWG)-based node structure. We present performance simulation results in terms of packet loss ratio and internal block probability. Internal blocking is an inherent problem of AWG optical routers, and a specific wavelength assignment algorithm has been developed to minimize it. Finally, the feasibility of IM/FSK transmission is experimentally demonstrated over an 88-km single-mode fiber span, and novel aspects of FSK generation and detection techniques are presented.     

A 40 Gb/s IM payload/2.5 Gb/s header AOLS technique based on an all fiber realization

An all fiber IM/FSK coding technique for the realization of the 2.5 Gb/s NRZ label swapping onto a 40 Gb/s NRZ payload signal has been numerically studied in this work. Four wave mixing (FWM) and cross phase modulation (XPM) on a dispersion shifted fiber (DSF) are used, for the combination of the Intensity modulated (IM) payload with Frequency Shift Keying (FSK) modulated header synchronously on the same optical carrier, and for the header removal and payload wavelength conversion respectively. Simulations have proven the feasibility of this DSF fiber based method, and shown the potential for high bit rate AOLS applications.     

Narrow-FSK optical packet labeling scheme for optical ethernet networks

In this work, an intensity modulation/frequency-shift keying (IM/FSK) orthogonal modulation scheme is achieved by direct modulation of a distributed feedback laser source using its adiabatic chirp characteristics. Optical frequencies for "1" and "0" bits are separated only 0.7 GHz, obtaining a narrow-FSK modulation and, accordingly, a low residual intensity modulation. Ethernet frames at 1.25 Gb/s (GbE) are transmitted with a label inserted using coded mark inversion codification at a 155-Mb/s rate. Error rates for the Ethernet payload and for the label have been measured for different payload extinction ratios, showing the viability of this scheme for distances up to 25 km.     

Corona Based Optimal Node Deployment Distribution in Wireless Sensor Networks

This paper shows the trade off between different modulation techniques such as multi level quadrature amplitude modulation, multi level phase shift keying, and multi level differential phase shift keying for upgrading direct detection optical orthogonal frequency division multiplexing systems with possible transmission distance up to 15,000 km and total bit rate of 2.56 Tb/s. The 2.56 Tb/s signal is generated by multiplexing 64 OFDM signals with 40 Gb/s for each OFDM. Variations of optical signal to noise ratio (OSNR), signal to noise ratio (SNR), and bit error rate (BER) are studied with the variations of transmission distance. Maximum radio frequency power spectrum, and output electrical power after decoder are measured for different multi level modulation techniques with carrier frequency. It is observed that multi level QAM has presented better performance than multi level PSK and finally multi level DPSK in optical OFDM systems. Maximum output power after decoder is enhanced with both 32-PSK, and 64-QAM. Quadrature signal amplitude level at encoder is upgraded with 64-QAM. It is noticed that OSNR, SNR, and BER are improved using 4-QAM OFDM system than either QPSK or 4-DPSK.     

A full-duplex optical access system with hybrid 64/16/ 4QAM-OFDM downlink

A full-duplex optical passive access scheme is proposed and verified by simulation, in which hybrid 64/16/4-quadrature amplitude modulation (64/16/4QAM) orthogonal frequency division multiplexing (OFDM) optical signal is for downstream transmission and non-return-to-zero (NRZ) optical signal is for upstream transmission. In view of the transmitting and receiving process for downlink optical signal, in-phase/quadrature-phase (I/Q) modulation based on Mach-Zehnder modulator (MZM) and homodyne coherent detection technology are employed, respectively. The simulation results show that the bit error ratio (BER) less than hardware decision forward error correction (HD-FEC) threshold is successfully obtained over transmission path with 20-km-long standard single mode fiber (SSMF) for hybrid downlink modulation OFDM optical signal. In addition, by dividing the system bandwidth into several sub-channels consisting of some continuous subcarriers, it is convenient for users to select different channels depending on requirements of communication.     

Design of mm-RoF system based on OFM technique with optimized OFDM modulation

We present the design of a novel bi-directional millimeter-wave radio-over-fiber (mm-RoF) system based on the millimeter-wave generation by optical frequency multiplication (OFM). A dual-drive Mach-Zehnder modulator is used to generate high-order optical side-modes which beat in the photo-detector, producing a 40-GHz carrier. Over 100-Mb/s orthogonal frequency division multiplexing (OFDM) modulation scheme is employed. The emphasis is on developing a mathematical model for optimizing optical modulation index to the Mach-Zehnder intensity modulator (IM) for OFDM signal with high peak-to-average power ratio which imposes a limitation on the system bit error rate (BER) performance due to the non-linearity of IM. The theoretical analysis on composite carrier to composite triple beat ratio is performed based on which extension to the system BER formula for quadrature phase shift keying/ multiple quadrature amplitude modulation (QPSK/MQAM) format is presented. The experimental proof is given in a 40-GHz RoF system at a bit rate of up to 280 Mb/s in 100-MHz bandwidth.     

Demonstration and Scalability Analysis of All-Optical Virtual Private Network in Multiple Passive Optical Networks Using ASK/FSK Format

We present a scalable all-optical virtual private network (VPN) in a two-stage passive optical network (PON) architecture to connect optical network units (ONUs) in different sub-PONs. It provides efficient access and VPN service covering a wider area. The scheme employs amplitude-shift keying/frequency-shift keying (FSK) orthogonal modulation formats, which are used for the VPN and upstream traffic at 625 Mb/s and 5 Gb/s, respectively. At the optical line terminal side, a fiber Bragg grating reflects one of the two frequency components in the FSK signal back to the ONUs in a same VPN. Using a bidirectional amplifier, the power budget and the scalability of the network are significantly improved, as evidenced by numerical analysis using the parameters in the experiment.     

Optical Packet-Switched Network Employing Optically Labeled 114-Gb/s RZ-8PSK Packet Signals Through Straight-Line Optical Wavelength-Selective Switching Nodes

We experimentally show the first demonstration of optically labeled 100-Gb/s packet polarization-multiplexing signals passing through four optical wavelength-selective switching (OWSS) nodes. In this architecture, the payload is generated by polarization-multiplexing return-to-zero octaphase-shift-keying format at 114 Gb/s, and 2.5-Gb/s on–off keying signal is used for the carrying label. By using the vestigial sideband filtering, the spectra efficiency is increased up to 1 b/Hz/s. The bit-error-rate performance for both payload and label are evaluated after passing through four straight-line OWSS nodes in this optical network.      

PolSK Label Over VSB-CSRZ Payload Scheme in AOLS Network

A novel orthogonal modulation scheme of polarization-shift-keying label over vestigial sideband payload is proposed and experimentally demonstrated over a 43-Gb/s all-optical-label-switching transmission. With this scheme, a high extinction ratio of the label is reached, while a spectral efficiency of 0.8 b/s/Hz is achieved by weakening the imperfection of the high-speed pulse sequence in polarization modulation. Furthermore, this modulation scheme is relatively irrelevant with payload bit rate. The payload and label penalties after 80-km NZDSF fiber transmission and label erasure are 1.5 and 1 dB, respectively. The influence of filter center frequency offset is also investigated. Besides, a label rewriting method is introduced to simplify label processing in intermedia nodes. All these results show that this scheme can be a candidate technique for the next-generation optical network.     

Study of Optical Transmission Performance in IP‐over‐WDM Networks Based on FSK/ASK Combined Modulation Format

The transmission performance of optical labeling based on a combined frequency shift keying/amplitude shift keying (FSK/ASK) format is studied by numerical simulation. The simulation demonstrates that the bit‐error ratio (BER) characteristic of an ASK signal is limited by the extinction ratio, received optical power, and dispersion, simultaneously. However, an FSK signal is mainly limited by the extinction ratio (ER) and received optical power when the peak spectrum, which is used to detect the FSK signal, is relatively narrow.     

基于级联马赫-曾德尔调制器的太赫兹通信系统

为了有效解决太赫兹通信系统中信号难以调制,影响通信系统性能的问题,提出了一种基于级联马赫-曾德尔调制器的太赫兹通信系统。将要传递的伪随机不归零码与频率为10GHz的射频本振信号混频后调制到级联马赫-曾德尔调制器上,通过调节两个调制器的偏置电压,使其分别偏置在最大传输点和最小传输点上,得到的光载波信号经过光放大器放大,结合高非线性光纤的四波混频效应,利用相移布喇格光栅进行模式选择,经过光电转换后的太赫兹信号通过基带数据恢复,可以得出该太赫兹通信系统传输的误比特率。结果表明,基于级联马赫-曾德尔调制器结构可以将太赫兹信号的产生与调制结合到一起。该研究对太赫兹通信系统的实用化有一定借鉴意义。     

一种载边比可调单边带全双工光载无线系统

理论分析了一种基于双平行马赫曾德尔调制器(MZM)的2倍频光单边带调制方案,仿真研究了基于该方案的载波重用全双工光载无线(RoF)通信系统性能.合理设置射频驱动信号相移及双平行MZM主调制器偏置电压产生单边带信号,再调整调制指数以实现光载边比ROCS的连续可调谐.讨论了射频信号相移、主调制器偏置电压、双平行MZM消光比...