扫频相干探测光谱幅度码标记交换系统的传输性能分析

基于光谱幅度码(SAC)标记的生成原理,利用扫频相干探测技术,搭建对156Mbit/s SAC标记进行识别的SAC标记交换系统。加载40Gb/s强度调制(IM)净荷信息后,分别对背靠背、40km和80km传输距离下,本振光源(LO)线宽、发射功率以及净荷与标记频率间隔对标记接收质量的影响进行仿真分析。同时分析接收光功率(ROP)、光信噪比(OSNR)、标记与净荷频率间隔对净荷误码(BER)特性的影响。结果表明:传输40 km、80 km后,标记接收眼高度(EH)与背靠背系统相比差别较小,且都能达到-0.6 dB左右;同时,传输80 km后,当净荷BER为10-9时,其ROP与OSNR分别为-17.8dBm和14.5dB。     

16QAM/PPM光标记交换系统的仿真研究

提出一种脉冲位置调制光标记(PPM)与正交幅度调制(QAM)净荷相结合的光标记交换系统。利用仿真对携带40Gbit/s 16QAM净荷和2.5Gbit/s 2PPM标记的系统传输特性进行验证。通过优化系统频率间隔,得到BER=10-9时,标记和净荷的接收灵敏度与光信噪比(OSNR)分别为-28.51dBm/13.65dB和-22.03dBm/15.02dB。经96km光纤传输后,传输代价均未超过1.5dB。结果证明:16QAM/2PPM光标记交换系统具备良好的传输特性。     

基于8PSK的新型高速正交光标记交换技术

提出了一种以八相移键控(8PSK)为净荷、ASK为标记的新型高谱效率高速正交光标记交换技术,首次实现了100 Gbit/s的高速正交光标记信号的80 km传输.分析了光信噪比(OSNR)、窄带滤波效应、信道中的非线性效应对标记与净荷性能的影响,并采用平衡相关探测和多符号相位估计(MSPE)技术实现了净荷8PSK信号的接收.与传统接收方式相比,8PSK净荷在相同误码率条件下,OSNR容限提升了约3 dB.经过80 km传输,ASK标记在BER=10~(-9),时OSNR为22.8 dB,8PSK相应的OSNR为20.3 dB.     

DQPSK/ASK正交调制光标记交换系统的研究

将DQPSK净荷引入正交调制光标记交换系统.利用仿真,对携带40Gb/s RZ-DQPSK净荷和2.5Gb/s ASK标记的系统传输特性进行验证.优化系统消光比和色散补偿方案,得到BER为10-9时,标记和净荷接收灵敏度与光信噪比分别为-24.1/-22.95dBm和16.1/18.85dB;经96km光纤传输后,传输...     

基于POLMUX-CSRZ-DQPSK/DB的新光标记流研究北大核心

针对现有的正交调制OLS(光标记交换)系统传输容量小且标记和净荷间串扰大的问题,提出了一种以POLMUX(偏振复用)-CSRZ(载波抑制归零)-DQPSK(差分正交相移键控)为净荷、DB(双二进制)为标记的新型正交调制光标记流编码方案。研究结果表明:当误码率为10-9时,系统最大传输距离达到了1 380km,净荷和标记的接收机灵敏度分别为-4.364和-4.268dBm,标记和净荷的传输功率代价均未超过1.8dB,净荷携带标记的功率代价未超过0.8dB。     

基于调频调幅方式的光标记网络的传输性能

数值模拟了IP-over-WDM光网络中基于频移键控/幅移键控(FSK/ASK)正交调制的光标记信号/净荷的传输性能.结果表明,ASK净荷的传输同时受到调制器消光比、接收光功率及光纤色散的影响;FSK光标记信号则主要受到调制器消光比和接收光功率的影响,几乎不受光纤色散因素的影响.     

40Gb/s DWDM系统不同码型传输性能的比较

采用Optisystem软件,对比分析了非归零码(NRZ)、归零码(RZ)、载波抑制归零码(CS-RZ)和载波抑制归零差分相移键控码(CSRZ-DPSK)四种码型在8×40Gb/s DWDM系统的传输性能。结果表明,CSRZ-DPSK码抗色度色散和PMD性能最优,CS-RZ码的OSNR容限最低。当入纤光功率适中、色散和色散斜率同时补偿时,CSRZ-DPSK码和CS-RZ码的最大传输距离超过2700km。     

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.     

40 Gbit/s传输系统的OLP解决方案研究北大核心

为了寻找一种可行的针对40Gbit/s传输系统的OLP(光线路保护)解决方案,分析了40Gbit/s传输系统保护所面临的色散补偿、光功率补偿和系统OSNR(光信噪比)等方面的挑战,介绍了针对40Gbit/s传输系统的色散补偿方案,并对一个应用案例进行了分析说明,验证了该解决方案的可行性。     

一种基于SOA的XGM效应构成的XOR光逻辑门实现光标记交换的方法

提出了一种基于半导体光放大器(SOA)的交叉增益调制(XGM)效应构成异或(XOR)光逻辑门实现光标记交换的方法,并将该方法应用于载荷采用DPSK调制/光标记采用ASK调制的正交调制光标记交换系统中,以此来验证其可行性。通过仿真,在载荷信息速率为10Gbit/s,标记信息速率为2.5Gbit/s的非归零码DPSK/ASK正交调制光标记交换系统中实现了标记交换。     

Transmission performance of implicit optical label switching system with coherently detected spectral amplitude code labels

A new optical label switching system with coherently detected implicit spectral amplitude code (SAC) labels is proposed in this paper. The implicit SAC labels are recognized using a frequency-swept local light source oscillator. An explicit SAC-label switching system with 40 Gbit/s intensity modulation (IM) payloads and 156 Mbit/s label and an implicit SAC-label switching system with 2.5 Gbit/s IM payloads and 156 Mbit/s label are both considered. Label and payload bit error rate (BER) performance is assessed and compared by simulations. The results reveal that after 80 km transmission and at the BER of 10-9, the received optical power (ROP) values of label and payload are -8.3 dBm and -23.5 dBm in implicit SAC-label switching system, respectively, while those are -18.2 dBm and -18.6 dBm in explicit SAC-label switching system, respectively. As a result, the payloads of 40 Gbit/s and 2.5 Gbit/s in explicit/implicit SAC-label switching system have little influence on the received payload quality at the BER of 10-9 after 80 km transmission. Finally, a payload of 40 Gbit/s can obtain 12.5 dB optical signal-to-noise ratio (OSNR) after 80 km transmission.     

Label Stacking in Photonic Packet-Switched Networks With Spectral Amplitude Code Labels

Label stacking is used for hierarchical addressing to reduce the size of lookup tables and to increase the speed of the routing process. We propose an optical label stacking using spectral-amplitude codes (SAC) as labels to accomplish ultrafast packet forwarding. We discuss the advantages of this label architecture compared to other proposals in the literature and present experimental results. We experimentally examine two types of optical packets, one with separable SAC labels and the other one with SAC-encoded payloads. In the first case, the SAC label is a collection of spectral tones modulated at the packet rate (low rate), and the payload is on a separate wavelength modulated at the data rate (fast rate). In the second case, the payload data modulates the collection of wavelengths that constitute the code. We implement a network with two forwarding nodes, and we transmit the packets with two labels in the label stack over 80 km of fiber and measure the bit error rate (BER) after two hops. We achieve error-free transmission (BER<10 ^-9) for the packets with SAC labels and SAC-encoded payload at payload bit rates of 10 and 2.5 Gb/s, respectively. This is the first experimental demonstration of optical label stacking to our knowledge     

Improve the performance of orthogonal ASK/DPSK optical label switching by DC-balanced line encoding

Orthogonal amplitude shift keying/differential phase-shift keying (ASK/DPSK) labeling is a promising approach to ultrahigh packet-rate routing and forwarding in the optical layer. However, the limitation on the payload extinction ratio (ER) is a detrimental effect for network scalability and transparency. This paper presents theoretical and experimental studies of ASK/DPSK labeling. It proposes that dc-balanced 8B10B coding can greatly improve ER tolerance, which in turn leads to better system performance. By using the 8B10B coding method, the paper demonstrates transmission and optical label swapping for a 40 Gb/s ASK payload and a 2.5 Gb/s DPSK label with an overall power penalty of 3.3 dB for the payload and 0.3 dB for the label. The experimental results also show that the ER is allowed to be as high as 12 dB.     

Optical Packet Switching via FWM Processing of Time-Stacked Weight-2 Codes

We demonstrate recognition of time-stacked multiwavelength (M-$lambda$ ) weight-2 code labels using four-wave-mixing (FWM) sideband allocation and selective optical filtering. At the forwarding node, the labels are separated using a highly reflective fiber Bragg grating and the FWM terms are generated using a highly nonlinear semiconductor optical amplifier. We show successful forwarding of packets through a two-hop network. We report error-free transmission (bit-error rate $≪ 10 ^{-10}$) of the payload through the entire network with less than 1.5-dB power penalty.      

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 architecture of optical code label processing in parallel designed for all optical routing system

A novel architecture of optical code label routing is designed based on optical code division multiplexing techniques, which performs the data packet forwarding and processing in parallel with a way of making the label and payload encoded and decoded separately. It uses optical polarity characteristics to realize the separation of the label and payload, employs fiber Bragg grating to encode/decode the label and payload so as to process them in parallel, and makes the forwarding and routing process realized in the optical domain. In the core router, the separation of the label and payload guarantees that the switch processing only includes the short label code recognition, without processing the payload. The payload recognition is carried out in the edge router. Thus, the router can simplify the processing of encoding and decoding in the core router, accelerating the switching, and increase the throughput greatly. Moreover, the novel routing scheme not only supports the varying of data packets, transparent transmission, fine granularity switching, and so on, but also is suitable for the aggregation of data service. It is attractive for the future development of all optical routing.     

Investigation of Dispersion Compensation in 2.5 Gbit/s OOK Label and 40 Gbit/s RZ-DPSK Payload Optical Label Switching System Based on Optical Carrier Suppression and Separation

Three dispersion compensation schemes of an optical label switching transmission system were investigated, which employs 40 Ghit/s return zero differential phase-shift keying(RZ-DPSK) payload labeled with 2.5 Gbit/s on-off keying(OOK) signal based on the optical carrier suppression and separation(OCSS) technique. In the system, proposed are the receiver sensitivity of payload and label, achieving -32.4 dBm and -38. 5 dBm, respectively. Using the optimal dispersion compensation scheme, after transmitted over 160 km and 320 km SMF respectively, the label can be recovered without power penalty, while the payload can be recovered with less than 2 dB and 5 dB penalty, respectively.     

Optimization of Key Parameters in 622-Mb/s Amplitude Shift Keying Labeled 40-Gb/s Return to Zero Differential Phase Shift Keying Optical Switching Network

Optimized are the label extinction ratio and dispersion compensation of an optical label switching transmission system, which employs 40-Gb/s return to zero differential phase shift keying（RZ-DPSK） payload labeled with 622-Mb/s amplitude shift keying（ASK） control data. In our scheme, the receiver sensitivities of payload and label achieves -27.8 dBm and -33.5 dBm, respectively. After transmitted over 40 km, 60 km and 80 km single mode fiber（SMF）（with dispersion compensation） respectively, the payload can be recovered with no power penalty, while the label can be recovered with less than 2 dB penalty.