基于MR-BPSK技术的超长跨距光传输

提出了一种全新的MR-BPSK(受控旋转二进制相移键控)方法。通过预定义的二进制序列,将BPSK(二进制相移键控)信号随机进行0°或者90°旋转,所得到的伪QPSK(四相相移键控)信号能够通过传统CMA(恒模算法)进行恢复。采用上述方法,成功实现了2Gbit/s速率、440km的无中继传输。     

521 km超长站距无中继光传输系统研究

文章介绍了利用新型SMF-28 ULL超低损耗光纤作为传输介质,使用相位啁啾、前向拉曼、增强型前向纠错(FEC)以及前置随路远程泵浦光放大(ROPA)技术,实现了2.5 Gbit/s系统无中继521 km的超长站距传输,这也是迄今所报道的使用前置随路ROPA技术所实现的距离最远的传输.     

Bit-dependent degradation caused by stimulated Brillouin scatteringin CPFSK coherent optical repeaterless systems with booster amplifiers

An interesting phenomenon due to stimulated Brillouin scattering (SBS) is experimentally found in a CPFSK heterodyne system with a booster amplifier. We find that the demodulated waveform amplitudes of just a few distinguished bits are strongly suppressed leading to a significant increase in BER. It is confirmed that the BER degradation can be reduced by adjusting the threshold voltage bias of the receiver decision circuit     

10ns～500ns宽度连续可调的快速光脉冲发生器

脉宽可调的脉冲发生器常用于精密检测。本文阐述了一种运用叠加原理设计的脉冲宽度从10ns到500ns连续可调的快速光脉冲发生器。在驱动电路中应用了脉冲叠加原理。     

光纤传输光电检测脉冲间隔与宽度双重调制

文章给出了脉冲时间调制的分类方法及实现方案。推导了非同步型脉冲间隔与宽度双重调制（ Ｐ Ｉ Ｗ Ｍ） 的频谱及其特点。说明了 Ｐ Ｉ Ｗ Ｍ 是模拟信号测量的一种经济有效的调制方法,在光纤传输光电检测中有广泛应用前景     

Modeling high-speed optical transmission systems

Computer simulation of a 2.5-Gb/s intensity-modulated/direct-detected optical system with high path dispersion is described. This simulation, based on single-mode laser diode rate equations, includes transmit and receiver circuit filtering, receiver circuit noise, avalanche photodiode noise, fiber dispersion, and laser chirp. The rate equations are sufficiently general to model mode-offset distributed feedback laser diodes. The system power penalty, due to laser chirp and fiber dispersion, is calculated using Gaussian quadrature numerical integration. By simulating a population of some 12800 laser diodes and correlating the performance of each laser in a transmission system with its spectral characteristics, it is possible to deduce laser specifications that will assure satisfactory operation in long-span links. These results are used to study a laser diode specification under consideration by CCITT, and, by studying the simulated laser line shapes, some modifications to the CCITT specification are considered     

Skew-free parallel optical transmission systems

This paper proposes two kinds of parallel line codes based on multiplexing and nonmultiplexing, and a method of automatic skew suppression based on bit synchronization and frame synchronization. This achieves parallel high-speed optical transmission to overcome bottlenecks in parallel electronic transmission and to increase the distance of high-throughput interconnections. We have developed GaAs coder/decoder large-scale integrations (LSIs) for the coding algorithm and skew suppression, and analog LSIs for compact, low-power, highspeed parallel optical links. Experimental results show that our proposed parallel transmission methods and fabricated LSIs can play a key role in realizing high-speed, long-distance parallel transmission and in reducing the size and power consumption of high-throughput parallel optical links     

Nonlinear noise amplification in optical transmission systems with optical phase conjugation

Taking into account the influence of group-velocity dispersion (GVD) and the nonlinear Kerr effect, the nonlinear amplification of the amplified spontaneous emission (ASE) noise in fiber transmission systems using optical phase conjugation (OPC) is studied. Under a path-averaged power approximation for long-haul transmission systems, an equivalent system is developed to evaluate ASE noise amplification and accumulation in OPC systems. Combining the theoretical analysis and numerical simulations, the noise suppression effect in OPC systems is demonstrated and discussed. By using the numerical calculation method, the power variation along the system is involved in the evaluation of noise amplification. It is shown that the power variation through the system results in an imperfect compensation of the modulation instability (MI) effect, which furthermore causes the degradation of the noise suppression performance in OPC systems with anomalous dispersion.     

Simple polarisation-independent optical circulator for optical transmission systems

A simple polarisation-independent optical circulator has been developed. The circulator consists of a 45°Y3Fe5O12 rotator and a quartz rotator and two polarising beam-splitting cubes. Measured insertion loss was about 1.3 dB at 1.32 ?m wavelength. The circulator was connected to graded-index multimode fibres using rod lenses.     

252 km repeaterless 10 Gb/s transmission demonstration

Using a practical erbium-doped fiber postamplifier, a dual-stage optical preamplifier, a lithium niobate Mach-Zehnder external modulator and a dispersion-shifted line fiber, IM/DD repeaterless transmission over 252 km at 10 Gb/s with a wavelength-independent receiver sensitivity in the 1530-1565-nm range is achieved     

Constraint-based design of optical transmission systems

The last decade has witnessed wide-scale deployment of optical networks to support the growing data traffic. This success can be traced back to advances in optical transmission systems such as dense wavelength-division multiplexing, Raman amplification, etc., which allow a single fiber to carry several wavelengths very far, while sharing expensive equipment. However, these cutting-edge technologies require careful placement of amplifiers and other network elements to ensure error-free propagation of the signal and to minimize costs. In practice, it is common to use a set of constraints to ensure valid configurations for deployment. It is nontrivial to identify the optimal configuration under all but the simplest constraints. In this paper, we consider a set of constraints with varying flexibilities and present algorithms for efficiently computing the cost-optimal configuration under them. We also present experimental and theoretical results to evaluate the various constraints and algorithms.     

Frequency-domain equalisation for optical transmission systems

The first optical single-carrier (SC) transmission system to employ frequency-domain equalisation (FDE) is proposed; 25 Gbit/s SC with FDE is demonstrated in severe chromatic dispersion conditions. The results show that SC with FDE is very tolerant of the chromatic dispersion.     

Integrated optoelectronics for optical transmission systems

A brief overview is given of research on optoelectronic integrated circuits (OEICs). Their performance, design, and manufacturing advantages are discussed. Device approaches and state-of-the-art OEICs are described. Future prospects for OEICs are considered     

Jitter accumulation in optical transmission systems

Jitter accumulation on a high-bit-rate submarine optical link has been investigated through signal circulating experiments. One-, 6- and 12-repeater loops exhibit similar accumulation. The variance of the systematic jitter increases as the number of repeaters and the random jitter tends to saturate.     

光传输网管海量数据存储访问研究

文章主要针对光传输网管系统中网无数量急剧增长导致的网管数据库更新查询效率极低,甚至出现系统崩溃的问题,提出了一种高效的分布式数据库系统架构.该系统采用主从技术、Memcached技术与分布式数据库结合的方式,将数据分散地存储在多台独立的设备上,提高了数据的查询效率.系统容量大、可靠性高、扩展能力强,具有很强的实用性.     

脉冲式半导体激光器准直光学系统的设计

根据具体的探测环境和探测精度,通过理论分析,提出了脉冲式半导体激光器准直光束的单透镜设计方法和柱面透镜的设计方法,并且给出了具体的设计参数。可以获得高斯光束的准直发散角为1.48mrad;高斯光束的腰粗为0.325mm。     

Performance evaluation of optical fiber transmission systems

A method is presented for evaluating of error probability for optical-fiber communication systems in the present of intersymbol interference and additive noise. It is based on deriving a best approximation, in a minimax sense, for the cumulative distribution function of the additive noise. The method takes into account the avalanche photodetector's non-Gaussian shot noise statistics. The additive noise is also not constrained to be Gaussian. Examples are presented for comparison to previously published techniques     

Error probability in optical fiber transmission systems

A method for evaluating the average error probability in digital fiber optic transmission systems is described. It takes into account the statistical properties of the main impairments that affect the information signal, i.e., shot noise (dark current included), thermal noise, and intersymbol interference. Unlike other methods, the analysis of shot-noise statistics does not entail the second-moment characterization alone, but uses a number of moments sufficient to evaluate the error probability with a high degree of accuracy. For this purpose it is shown how the cumulants of shot noise and intersymbol interference of any order can be computed. The baseband pulse response and the statistical distribution of the avalanche-photodetector gain are assumed to be available. Moreover, techniques for exploiting the cumulants are given; knowledge of the cumulants allows one to compute the probability of error by means of Gaussian numerical integration rules. Finally, some results and comparisons are reported.     

Bidirectional optical fiber transmission systems using Ramanamplification

Bidirectional optical fiber transmission systems using Raman amplification are discussed. Analytical expressions for signals amplified by both forward and backward Raman scattering are presented. It is found that there exists an optimal pump power for the maximum unrepeated transmission length in a bidirectional system and that the maximum length is about 450 km, which is about the same as that of the unidirectional system     

Long-span optical FSK heterodyne single-filter detection transmission experiment using a phase-tunable DFB laser diode

High receiver sensitivity (?51.9 dBm) and long span (243 km) transmission expriments have been achieved with a 140 Mbit/s optical FSK heterodyne single-filter detection system, using a phase-tunable DFB laser diode as a transmitter. This has enabled direct FSK modulation without waveform distortion. Also, a 280 Mbit/s 204 km transmission experiment has been carried out successfully.