光纤环路控制器及其在光OFDM传输系统的应用

设计了基于FPGA的光纤环路控制器,该控制器可以动态调整信号注入时间、单圈循环时间和传输圈数,搭建了环长160km的光纤环路实验平台,进行了5Gb/s的DD-OFDM 320km的环路传输实验。通过实验证明,光纤环路实验平台性能稳定可信,环路控制器输出精准、操控方便。     

基于弯曲损耗的光纤环路温度传感器

为实现高精度光纤温度传感,本文对新型光纤环路温度传感器进行研究。该传感器通过折射率的改变感知环境温度变化,并直接影响到光在光纤中的传输损耗。通过分析温度、弯曲半径对折射率的影响,即弹光效应和热光效应。给出了传输损耗、测温范围与弯曲半径的关系,并依此进行了测温精度和稳定性实验,实验结果表明,功率型光纤环路温度传感器具有精度较高、成本低、易于集成等优点。     

单片机控制实现的光纤环路传输实验

设计了以80C552单片微机为核心、接口和爱德万Q8384误码测试仪匹配的环路控制器，实现了信号注入时间、环长、传输环数和测试控制的动态可调。以此环路控制器为基础，搭建了一个4路CSRZ码、单环传输光纤长度为240km的10Gb／s的WDM光纤环路传输系统，进行了传输560km功率代价小于1dBm的传输实验。以此传输系统为对象，分析研究了环路控制器各个控制信号误差对环路系统性能的影响。结果发现，当测试时间对信号前端留出足够余量后，可以有效避免系统瞬态效应对测试的影响。     

微蜂窝无线用户环路通信技术

改革开放以来,我国电信网数字化技术飞速发展,尤其在光纤传输数字化和数字程控交换方面,取得了举世瞩目的成就.然而整个网路中,面广量大随处可见的市内电话用户环路依旧是有线模拟网.如何实现用户环路数字化,目前有两种技术方法.其一就是所谓窄带综合业务数字网N—ISDN,将数字化信号在电缆用户线上传输至终端设备.其二就是用微蜂窝无线技术实现市话用户环路的     

用光纤环路镜实现WDM系统中的EDFA增益均衡

EDFA对不同波长的光产生的增益不同 ,这种增益不平坦特性成为 WDM系统中高速率、大容量信息传输的障碍 ,因此对 EDFA的增益进行均衡就显得特别重要。介绍用光纤环路镜实现 EDFA增益均衡的机理 ,并进行了实验 ,结果表明该方法简单易行 ,均衡效果显著     

全光传输系统的监控技术研究

介绍了一种全光传输系统的监控技术。监控信息由主信道之外的光波承载,在由传输光纤、端站和光放大器构成的环路中,以帧的方式进行传递,实现了整个系统工作状态的监视和控制。     

基于载波抑制双边带的光纤微波频率传递系统优化

针对采用分立器件实现载波抑制双边带(DSBCS)调制的被动补偿光纤环路微波频率传递方案的缺陷,对基于DSBCS调制的光纤环路微波频率传递系统进行稳定性优化设计和测试验证,设计了基于微波芯片的一体化接入节点电路,以腔体分隔的金属和高精度的温度控制模块屏蔽串扰、减小外界温度影响,实验测试了系统电路底噪、60 km光纤环路系...     

有源光纤环路脉冲复制特性的研究

理论分析和实验验证了一种提高有源光纤环路脉冲复制性能的解决方案。首先,经过理论分析推导出决定脉冲复制性能的主要参数是光放大器增益的动态特性。其次,理论分析得出通过改变环路衰减,利用光纤环路内的放大自发辐射噪声光信号调整光放大器工作状态,减小光放大器增益的动态范围。最后,通过实验测量复制脉冲序列波形,验证了光放大器工作在深度饱和状态可以提高有源光纤环路脉冲复制的性能。并且通过实验测量光纤环路光谱,进一步分析证明光放大器饱和状态是指相应频带的饱和。因此使用光滤波器对光纤环路频带进行限制是非常必要的。     

用户环路光纤化的有效设备：CT／RT传输设备

日本推行的ＣＴ／ＲＴ传输设备是促进用户环路光纤化的一种非常有效的设备，它可以经济地提供多样化的业务。这种设备的推广应用有利于光纤用户网的普及和“光纤到家庭”目标的最终实现。     

光孤子通信——未来的光通信技术

光孤子通信是实现超长距离高速通信的重要手段，它被认为是第五代光纤通信系统。近年来美、日、英等国相继进行了光孤子通信实验。美国的贝尔实验室先后进行了传输距离为4000km、6000km、15000km的光孤子传输实验，验证了光孤子跨洋通信的可能性，并且完成了32Gb/s传输90km无误码光孤子数据传输实验。日本的NTT公司在完成了5Gb/s传输400km和10Gb/s传输300km实验的基础上，又完成了20Gb/s传输200km和10Gb/s传输1000km直通传输实验。有人用光纤环路的形式来验证光孤子通信的最终潜力，先后成功地实现了2.4Gb/s传输1200km、2.5Gb/s传输1400…     

Circulating loop transmission experiments for the study oflong-haul transmission systems using erbium-doped fiber amplifiers

A circulating loop transmission experiment is a useful tool for the research and development of long-haul transmission systems that use erbium-doped fiber-amplifier repeaters. Circulating loop techniques, applied to an amplifier chain of modest length, can provide an experimental platform to study a broad range of transmission phenomena for EDFA-based transmission systems. A loop experiment attempts to simulate the transmission performance of a multi-thousand kilometer long system by reusing or recirculating an optical signal through a modest length amplifier chain of tens to hundreds of kilometers. This paper reviews original loop techniques developed to study various parameters of long-haul transmission using erbium-doped fiber-amplifiers repeaters for undersea systems. Transmission experiments were performed at transoceanic distances with 33 and 46 km amplifier spacing, operating at 5 and 10 Gb/s. Experimental data is provided here for various parameters, including bit error ratio, Q-factor, and spectral broadening     

Multi-thousand kilometer optical soliton data transmissionexperiments at 5 Gb/s using an electroabsorption modulator pulsegenerator

We have demonstrated the transmission of data-coded optical soliton pulse at the bit-rate of 5 Gb/s over a few thousand kilometers. Ultra-short optical pulses generated with a sinusoidally driven electroabsorption modulator and a DFB-LD that were approximately hyperbolic-secant squared shape were transmitted through the fiber. Both recirculating loop transmission lines and straight transmission lines were used for the experiments. The pulse width was maintained well over 6,000 km transmission in the recirculating loop experiment. Three-thousand-km stable transmission was achieved using a straight-line setup at the bit-rate of 5 Gb/s, although the average fiber chromatic dispersion deviated slightly from the optimum value. The results indicate the possibility of the soliton transmission system for multi-thousand-km optical communication systems     

An optical PSK homodyne transmission experiment using 1320 nmdiode-pumped Nd:YAG lasers

A second-order optical phase-locked loop was constructed using 1320-nm diode-pumped miniature Nd:YAG ring lasers. Using the loop, a 140-Mb/s PSK homodyne transmission experiment was demonstrated over 28.6 km of single-mode fiber. With a loop natural frequency of 13 kHz and a damping factor of 0.6, the receiver sensitivity was -62.8 dBm, or 25 photons/bit. The authors believe this is the highest sensitivity obtained to date with any optical communication system     

Record amplifier span of 105 km in a soliton transmissionexperiment at 10 Gbit/s over 1 Gm

A record amplifier span of 105 km has been achieved in a soliton transmission experiment at 10 Gbit/s by making use of in-line synchronous modulation in a recirculating loop. Transmission over 1 Gm demonstrates once more the efficiency of this type of technique     

Optical 3R regenerator using wavelength converters based onelectroabsorption modulator for all-optical network applications

The optical 3R regenerator using electroabsorption modulators was evaluated at 10 Gbit/s in terms of the all-optical network application. Its reset of impairments induced by the fiber transmission was confirmed by carrying out the multiple recirculating loop experiment. The experimental result shows that the transmission distance could be extended by almost 1.5 times compared to the case when it was not used, inserting the optical regenerator between the two recirculating loops     

光纤AM CATV外调制发射机中组合二次失真CSO的控制

提出了一种易于实现的调制器偏置点控制方案,对其进行了理论分析,导出了误差信号的表达式,并进行了计算。实验结果表明,理论分析与实验相符。采用该方案,对于PAL/D 550MHz的电视系统,能够将发射机的CSO指标控制在-65dBc以下,满足实际使用的需求。     

Dispersion compensated 80 Gbit/s WDM transmission over 1171 kmstandard singlemode fibre

WDM transmission experiment at 80 Gbit/s (8×10 Gbit/s, 0.8 nm channel spacing) over 1171 km of standard singlemode fibre has been performed with a 90.1 km recirculating loop incorporating a dispersion compensation fibre and gain-equalising optical bandpass filters     

Influence of noise in optical pulse source on soliton transmission

This paper performed a 10-Gb/s optical soliton transmission experiment in a sliding frequency recirculating loop and found that the noise in the optical pulse source decreased error-free distance. This is because the mean frequency of soliton at the pulse source is modulated by the noise which results in the increase of timing jitter at the receiver even in a strong sliding frequency controlled soliton transmission line. Jitter in arrival time of transmitted solitons was theoretically analyzed to verify experimental results     

Nonlinearity tolerance of RZ-AMI format in 42.7 Gbit/s long-haul transmission over standard SMF spans

Comparison is made of 42.7 Gbit/s return-to-zero alternate mark inversion and return-to-zero on-off keying formats in a recirculating loop transmission experiment over 24/spl times/80 km standard singlemode fibre spans. It is found that RZ-AMI is more tolerant to fibre nonlinearity, in good agreement with theoretical and numerical predictions.     

Theoretical and experimental study of self-filtering effect inconcatenated erbium-doped fiber amplifiers

This paper describes the self-filtering effect which appears in concatenated erbium-doped fiber amplifier (EDFA) systems. Employing a theoretical model we observed how the self-filtering wavelength is affected by the variation of some EDFA parameters, such as gain, fiber composition, pump wavelength and temperature. By a recirculating loop experiment which simulates a concatenated repeater transmission system, we measured the evolution of the amplified spontaneous emission (ASE) spectra with the number of circulations, and with the loss of the loop. We found a good agreement between the theoretical simulations and the experiments