一种基于小波变换的OTDR事件分析算法的研究

简单分析了用 OTDR卡进行光纤检测的原理 ,根据小波分析检测信号突变点的理论 ,提出了运用小波分析对光纤断点及反射事件准确定位的方法。理论分析和实例计算表明 ,这种方法对 OTDR曲线中反射事件尤其是断点的定位非常准确 ,是一种行之有效的方法     

用于色散补偿的双芯光子晶体光纤设计

WDM系统的传输速率受单模光纤(SMF)中色散D的制约.针对WDM系统中的色散补偿问题,本文提出了一种新型的用于色散补偿的双芯光子晶体光纤(DCPCF),其构成材料是纯石英和空气.采用高斯--厄密函数法计算了此DCPCF的模场和等效折射率,理论模拟表明这种DCPCF的色散可达-18000 ps/(nm.km),并可补偿超过自身长度1000倍的普通单模光纤.     

光纤通信系统中色散补偿的研究

本文从光纤色散和啁啾光栅所提供的延时两方面对光通信系统中的色散补偿进行了分析，表明每隔放大器的中继距离插入一啁啾光栅进行色散补偿可实现信号无失真传输，在此基础上提出了在中继器中同时实现全光信号放大和色散补偿的光纤通信系统方案。     

色散缓变光纤中Raman孤子自频移效应的研究

利用绝热扰动法研究了色散缓变光纤中Ｒａｍａｎ孤子自频移效应，得到了色散缓变光纤中Ｒａｍａｎ孤子自频移的表达式。结果表明：光纤色散变化率存在一个可以有效抑制孤子自频移的阈值，当光纤色散变化率大于这个阈值时，色散缓变光纤可以抑制孤子自频移，而当光纤色散变化率小于这个阈值时，色散缓变光纤不仅不能抑制孤子自频移，反而加剧孤子自频移。     

Calculation of the Figure of Merit of Linearly Chirped Fiber Gratings for Dispersion Compensation

1IntroductionBecauseoftheadventoferbium-dopedamplifiers,thelengthoftheophcalfiberlinksisnolongerlicitedbytheabsorphon,butratherbythechromaticdispersionofthefiber.Especially'theophcalsignalshapeissoseriouslydestroyedthatthebit-error-rate(BER)isratherhigherinthelonghaulhigh-bit-rateophcalcommunicationsystem.Sothedispersionoffibermustbecompensatedbyvariouskindsofdevices.Amongthem,thecompensatorusingthelinearlychirpedfibergratingshascausedagreatinterestindispersioncompensatingdeVices11-5].Onemus…     

A Neural Network Method for Traffic Dispersion

１ＩｎｔｒｏｄｕｃｔｉｏｎＴｒａｆｉｃｄｉｓｐｅｒｓｉｏｎ［１］，ｗｈｉｃｈｍｅａｎｓｔｈｅｔｒａｆｉｃｉｓｄｉｓｔｒｉｂｕｔｅｄｏｖｅｒｍｕｌｔｉｐｌｅｐａｔｈｓａｎｄｔｒａｎｓｍｉｔｅｄｉｎｐａｒａｌｅｌ，ｉｓｕｓｅｄｔｏｉｍｐｒｏｖｅｔｈｅｎｅ...     

Theoretical Discussion of Couple-Mode Using Chirped Fiber Grating for Dispersion Compensation

１ＩｎｔｒｏｄｕｃｔｉｏｎＡｔｐｒｅｓｅｎｔ，ａｓｔｈｅｅｒｂｉｕｍｄｏｐｅｄａｍｐｌｉｆｉｅｒｓｈａｖｅｓｕｃｅｓｆｕｌｙｂｅｅｎａｐｐｌｉｅｄｔｏｏｐｔｉｃａｌｆｉｂｅｒｌｉｎｋｓ，ｔｈｅｌｏｎｇｈａｕｌｈｉｇｈｂｉｔｒａｔｅｏｆｏｐｔｉｃ...     

Equaliser Performance for HIPERLAN in indoor channels

In order to accomplish practical deployment modelling for system performance evaluation and comparison for possible modulation and equalisation schemes to be used in HIPERLAN, a wide band tapped delay line (WTDL) channel model has been adopted by ETSI to characterise the multipath fading in the indoor radio environment. Based on this statistical channel model, and using Monte Carlo method, this paper evaluates the average probability of error for linear and decision feedback equaliser as a function of signal-to-noise ratio. It also evaluates the matched filter bound for this channel model. The results show the optimum performance levels achievable via the use of any equaliser.The work described in this paper was supported by the UK DTI/EPSRC LINK project: PC2011 High Throughput Radio Modem under EPSRC grant reference GR/K00318 in collaboration with Symbionics Networks limited.     

Design of a flat field fiber with very small dispersion slope

We have given designs of a small dispersion fiber with large effective area and small dispersion slope. The fiber has flat modal field over the central part of the core, which provides large mode field diameter (8.3 μm at λ₀=1550 nm) leading to the relatively large effective area (A_eff=56.1 μm²) required to reduce nonlinear effects. The total dispersion of the proposed fiber is in the range of 2.7–3.4 ps/km/nm in the wavelength range of 1530 to 1610 nm, which covers the entire C- and L-bands of erbium doped fiber amplifiers. The dispersion slope at λ₀=1550 nm is 0.01 ps/km/nm², which is also very small.     

超声分散技术在制备小颗粒(Y,Gd)BO_3∶Eu~(3+)粉体中的应用

采用共沉淀法结合超声分散技术制备亚微米级红色荧光粉(Y,Gd)BO3∶Eu3+,研究了超声时间对离子混合及沉淀过程的影响,以及进而对粉体性能的影响。采用红外光谱(IR)、扫描电子显微镜(SEM)、粉末X射线衍射(XRD)、PDP真空紫外荧光粉测试系统对荧光粉的组成、结构与光学性能等进行表征,结果表明:(Y,Gd)BO3∶Eu3+中[BO3]基团中B原子以四配位为主,同时混有三配位,主体基质YBO3以六方碳钙石结构存在,空间群为P63/mmc(194),晶胞参数a=3.778,c=8.814;在离子混合和沉淀过程中经过超声分散制备的粉体与未经超声分散制备的粉体相比较,相对发光强度提高,色坐标红移(x=0.6392,y=0.3604→x=0.6422,y=0.3575),红橙比(626nm/592nm)提高12%,粒径细小,颗粒形貌均匀,分散性良好。