菏泽城区有线电视网络设计方案

介绍了菏泽城区有线电视网络的改造方案,主要讲述了网络设计的原则、思路及指标计算,以及方案构思的过程.     

密集波分复用技术在京九铁路的运用

本具体分析了京九线密集波分复用技术的组成和实现方法。     

初始啁啾对光脉冲放大影响的数值研究

文章通过数值计算研究了掺铒光纤放大器(EDFA)中超短光脉冲放大的情况.结果表明,当相邻两超短脉冲的初始间距较小时,两脉冲在放大过程中会相互吸引,并产生新的子脉冲,从而导致放大效果变差.增大初始间距并不能有效地改善放大效果.为此,提出对输入光脉冲对引入合适的初始啁啾的方法,该方法可以减小因光脉冲互作用带来的负面影响,提高脉冲放大质量.     

基于参数比较法的大信号功率攻击检测方法

介绍了大信号功率（HSP）攻击和参数比较法的原理;从理论上分析了用参数比较法检测光信噪比实现对HSP攻击检测的可行性,提出了大信号功率攻击的检测器件判决方法。仿真结果表明：被检测器件EDFA的输入和输出端光信噪比之差在有无攻击时的差值,随着攻击功率的增大不断增大,通过测量和计算,可以找出一个合适的差值作为门限来检测光网络中有无HSP攻击的存在。     

新时期网络的先进设计理念与几个热点问题

介绍新时期广电网络设计的一些新动向,包括1550nm城域网、1550nm市县联网、EPON＋EOC技术的组合、高电平输出光接收机的大量使用和集中分配等,就这些先进的设计理念在广电网络中的应用提出自已的看法。     

High-power EDFA applied in distributed optical fiber Raman temperature sensor system

In this paper, a high-power erbium-doped fiber amplifier (EDFA) for the temperature sensor system is theoretically designed and experimentally demonstrated. It consists of an erbium-doped fiber that is pumped bidirectionally with two 980-nm high-power laser diodes (LDs). At the EDFA input, an optical isolator (ISO) is used to ensure that the signal pulse transmits forward only. After that, a wavelength division multiplexer (WDM) is employed to combine the forward pump laser (980 nm) and incident optical pulse (1550nm) into the erbium-doped fiber for direct amplification in the optical domain. At the EDFA output, another WDM couples the backward pump laser (980 nm) into the erbium-doped fiber and outputs the amplified optical pulse (1550 nm) with an ISO followed to isolate the backscattering light. According to this structure, we carried out the experiment in the condition as follows. For 980 nm pump LD, the operating current is 590 mA, and the setting temperature is 25℃. For EDFA, the length of erbium-doped fiber is 12.5 m, and the power of 1550 nm input signal is 1.5 mW. As a result, the power of pump LD is 330 mW, and the power uncertainty is 0.5%. The power of EDFA output at 1550 nm is 300 mW, and the power uncertainty is ±3 mW.     

一种新型低噪声掺Er光纤放大器的研究

提出了一种新型的低噪声掺Er光纤放大器(EDFA)。将光波长交错器的输入端口与普通EDFA的输出端相连接,用于降低噪声,信号光由光波长交错器的偶信道端口输出。利用光波长交错器的梳状反射特性,抑制EDFA的放大自发辐射(ASE),改善EDFA的噪声特性,使其具有低噪声的特点。采用4m长的掺Er光纤(EDF)作为增益介质,小信号功率为-26dBm时,在1530～1560nm带宽范围内,测得低噪声EDFA的噪声系数低于3.83dB,仅比噪声系数的量子极限3dB大0.83dB。     

光环形网的光信噪比分析与系统设计

文章指出光环形网的设计中必须考虑最长环路保护时的光信噪比(OSNR)计算问题。导出了光分插复用／光交叉连接(OADM／OXC)节点级联的OSNR的计算公式。最后针对链路发生故障点不同的同一业务波长配置的保护倒换情况进行了OSNR的分析，给出了环路保护倒换情况下的OSNR最低条件的模型，并依据此模型建立了光环形网工程设计方法，简化了工程设计中OSNR验证的计算量。     

All-optical wavelength reuse with simultaneous upstream data and PPS timing signal transfer for flexible optical access networks

All-optical wavelength reuse is a viable approach for realization of low cost colourless ONUs. We experimentally demonstrate a novel all-optical wavelength reuse technique with simultaneous upstream data and pulse-per-second signal transfer, exploiting EDFA gain saturation with a holding beam. A DFB laser is modulated with 8.5 Gbps data and transmitted downstream over 24.7 km fibre. A saturated EDFA located at the ONU is adopted to reduce the extinction ratio of the downstream data from 6.2 dB to 839.1 mdB. This allows for data rewrite and wavelength reuse for upstream transmission. Receiver sensitivities of ?20.19 dBm and ?19.60 dBm are achieved at back-to-back analysis and 24.7 km downstream link respectively. A holding beam is further exploited to attain simultaneous carrier reuse and PPS clock upstream transfer. PPS jitter stability of 1.01 × 10^-08 ns and 6.64 × 10^-08 ns are attained respectively. This work offers a convenient all-optical wavelength reuse solutions for optical access networks.     

级联M-Z型掺铒光纤放大器增益平坦滤波器的设计

针对掺铒光纤放大器（EDFA）增益不平坦对波分复用（WDM）系统传输质量的影响，将有限冲激响应（FIR）滤波器的设计方法引入到级联Mach Zehnder干涉仪型EDFA增益平坦滤波器的设计中.利用混合遗传梯度算法，计算了级联Mach Zehnder干涉仪EDFA增益平坦器中各个耦合器的系数.对于给定的任意形状的EDFA增益谱，设计的EDFA增益平坦滤波器在1530~1560nm波长内误差为±0.25dB，计算时间约为其他方法的1/3，证明了该方法不仅可以得到理想的结果，而且可提高设计效率.