影响光纤寿命因素的探讨

为了预测光纤的寿命,对光纤寿命的影响因素(Weibull指数m,疲劳指数n,强度保持因子B)进行了详尽地探讨.如要获得高强度、使用寿命长(强度衰退慢)的光纤,就要充分注意光纤制作的每一环节,以期提高Weibull指数m;并合理地使用密封被覆技术提高光纤的疲劳指数n.     

A high gain, high output saturation power Pr/sup 3+/-doped fluoride fiber amplifier operating at 1.3 mu m

A high net gain of 30.1 dB at 1.309 mu m and an output saturation of 13 dBm are obtained using a Pr/sup 3+/-doped fluoride fiber amplifier pumped at 1.017 mu m. The critical Pr/sup 3+/ concentration at which concentration quenching begins to occur was obtained by fluorescence lifetime measurement. The Pr/sup 3+/ concentration should be less than 1000 ppm to suppress the concentration quenching by cross relaxation. A high signal output power of 17.8 dBm was extracted from the Pr/sup 3+/-doped fluoride fiber. The Pr/sup 3+/-doped fluoride amplifier shows good potential for use in 13. mu m telecommunication systems.<>     

Drawing influence on the lifetime of optical fibres

Strength and lifetime measurements carried out on optical fibers with different residual tensile stress at the surface are discussed. This stress was optically measured and included in the theory of fiber strength and lifetime. The strength results were compared with measurements done on pure silica fibers without residual stress. In lifetime predictions, this residual tensile stress in the outside region of the fiber has to be taken into account. However, the decrease in intrinsic strength was much larger than the increase in residual stress in the outside region of the fiber. This phenomenon, which is not well understood, depends on drawing conditions     

Reliability of fluoride fiber module for optical amplifier use

We report reliability test results for a fluoride fiber module. We developed a sealed fluoride fiber module for practical optical fiber amplifier use. Trouble-free damp heat storage and low-temperature storage for 5000 h and trouble-free temperature cycling and temperature-humidity cycling tests revealed that our fluoride fiber module has long-term stability under practical environmental conditions     

Heavy metal fluoride glasses and fibers: A review

A comprehensive summary is provided on the subject of heavy metal fluoride glasses. This includes discussions on glass compositions, preparation, structure, fiber drawing characteristics, and intrinsic and extrinsic optical properties. Other relevant glass and fiber characteristics such as strength, durability, and thermal Shock resistance are also outlined. Particular emphasis is given to the measurements of optical attenuation in fluoride glasses and their potential for use in ultralow-loss fiber optic waveguides. An excellent bibliography of recent work in the area of heavy metal fluoride glasses has been generated for those seeking more detailed information on this topic.     

Mechanical durability of ZBLAN and aluminum fluoride-based opticalfiber

Zero stress aging and static fatigue experiments were performed on fluoride glass fibers of ZBLAN and aluminum fluoride-based compositions to examine the mechanical durability in aqueous solutions. ZBLAN fiber, which has the higher initial strength, becomes weaker than initially lower strength aluminum fluoride-based fiber in less than one hour in pH 7 buffer solution at 30°C. This is shown to be due to dissolution of the glass and precipitation of crystals at the glass/coating interface. In 1N NaOH the solubility is higher, resulting in less precipitation and hence less strength degradation. Although ZBLAN fiber degrades more quickly when a high strain is applied, at low applied strain the residual strength is higher than is observed when do strain is applied. These results indicate that future work on fluoride glass fibers for use in aqueous environments should focus on optimization of the as-drawn strength of durable glass, such as aluminum fluoride-based material, rather than on making small strength improvements to already strong but less durable glass, since such improvements will be quickly lost in aggressive environments     

新型掺铒离子氧氟碲酸盐玻璃的光谱性质

探求新的具有优良的热学和光学性能的基质玻璃系统，是获得具有宽带宽和增益平坦的掺Er^3＋光纤放大器（EDFA）的一种有效途径。制备了一种新型氧氟碲酸盐玻璃TeO2-BaF2-LaF3，并对其热学性能和光学性质进行了测试。应用乍得-奥菲尔特（Judd-Ofelt）理论计算了Er^3＋离子的J-O理论参量和荧光寿命r。探讨了氟化物的引入对碲酸盐玻璃结构的改变的影响，并分析了其对玻璃的热学性质和光学性质的影响。实验发现，获得的氧氟碲酸盐玻璃具有优良的热学稳定性（△T=156.6C），宽的荧光半峰全宽（72nm），长的荧光寿命（r=4．9ms）以及良好的平坦增益特性。该玻璃系统有望成为新的宽带光纤放大器用基质玻璃材料。     

Strength assurance for stress-induced polarization-holding fibers

A new method of assuring strength for stress-induced polarization-holding fibers has been clarified on the basis of prooftesting. A simple equation considering the residual stress in a fiber is derived. Design diagrams for strength assurance of a polarization-holding fiber are shown. Using the diagrams, allowable applied stress and proof-testing conditions can be determined for a given failure rate and lifetime. The residual stress value and the strength parameter representing the strength distribution of inner cracks are quantitatively evaluated.     

Development of an efficient praseodymium-doped fiber amplifier

This paper describes the development of an efficient praseodymium-doped fluoride fiber amplifier (PDFA) using newly developed PbF₂-InF₃-based fluoride single-mode fiber. First, the spectroscopic properties of Pr³⁺ in PbF₂-InF ₃-based and ZrF₄-based fluoride glass are compared and then the fabrication of high-NA PbF₂-InF₃-based fluoride single-mode fiber is presented. The gain coefficients obtained with the developed fiber are 0.36 dB/mW with a forward pumping scheme and 0.4 dB/mW with a bidirectional pumping scheme. We use this newly developed fiber to construct two types of an efficient PDFA module. We realized a 19-in rack size PDFA module with a master oscillator/power amplifier laser diode (MOPA-LD) and a plug-in type PDFA module with a wavelength-stabilized 1.017-μm LD and describe their amplification characteristics     

面向链路稳定性的MANET路径建立机制

为了适应拓扑动态变化的Ad hoc网络,该文提出了一种面向链路稳定性的路由机制,节点根据少量接收信号强度样本值建立牛顿插值多项式描述连续时间域上的信号强度,进而在不预测节点运动方向和速度等相关参数的情况下估计链路生存时间,按照链路生存时间和跳数两个约束条件,源节点逐跳建立稳定的端到端路径。仿真结果表明,所建立的牛顿插值多项式能够准确地逼近节点随机移动过程中的实际接收信号强度,并且该路由机制能够有效地减少路由重建次数,降低数据包丢弃概率。     

Experimental measurement of gain in erbium-doped fluoride fiber amplifier in the 850-nm signal band

In this letter, we report an efficient single-mode Er/sup 3+/ doped fluoride fiber amplifier (EDFFA) in the 850 mn signal band. The Ti-sapphire laser was used to pump the EDFFA at 792 mm with an estimated absorbed pump power of 35 mW. The EDFFA used a 4.2 meter long NA=0.39, /spl lambda//sub c/=850 nm fluoride fiber as the active medium. A peak gain of 25 dB was observed at 852 mm. The gain was measured for a 10 nm region between 847.5 mn and 857.5 nm. The 3 dB gain bandwidth is less than 3 nm. However, the gain exceeded 20 dB over wavelength region of at least 7.5 nm. The gain and the gain bandwidth can be further increased by optimizing the length of the active fiber.     

通信用光纤可靠性影响因素分析

光纤的可靠性是保证光网络寿命的关键,可靠性由光纤的强度分布和疲劳行为共同决定.应用光纤的强度分布数据和蒙特卡洛方法,分析了筛选强度、应力腐蚀敏感性参数和载荷水平等因素对光纤可靠性的影响.分析结果表明,筛选强度的提高可改善筛选后光纤的强度分布,但同时会导致部分筛选后光纤的强度明显降低;按照基于幂定律理论的光纤疲劳行为模型...     

通信光纤可靠性问题的研究

为保证通信光纤在使用寿命内有正常的工作状态和特性,光纤的长期可靠性是一个至关重要的问题。关于光纤的可靠性有三个方面:(1)长期的机械强度;(2)由辐照引起的衰减变化;(3)氢对光纤损耗的影响。本文着重讨论这些方面的关键问题并强调对目前应用于光通信中光纤特性的理解。     

Relationship between texture and electromigration lifetime in sputtered AI-1% Si thin films

The relationship among the grain structure, texture, and electromigration lifetime of four Al-1% silicon metallizations produced under similar sputtering conditions was explored. The grain sizes and distributions were similar and the grain structure was near-bamboo for all metallizations. All metallizations exhibited a near-(111) fiber texture, as determined by the pole figure technique. Differences in electromigration behavior were noted. Three of the metallizations exhibited a bimodal failure distribution while the fourth was monomodal and had the longest electromigration lifetime. The electromigration lifetime was directly related to the strength of the (111) fiber texture in the metallization as anticipated. However, whereas the grain size distribution has an effect on the electromigration lifetime when metallization lines are several grains wide, the electromigration lifetime of these near-bamboo metallizations appeared independent of the grain structure. It was also observed that a number of failures occurred in the 8 μm interconnect supplying the 5 μm wide test lines. This apparently reflects an increased susceptibility of the wider interconnect lines to electromigration damage.     

Crosstalk in 1.3 μm praseodymium fluoride fiber amplifiers

Praseodymium-doped fluoride fiber amplifiers have been demonstrated to provide good gain, output power, and noise performance in the second telecommunications window. This paper presents a study of the crosstalk performance of these amplifiers. A theoretical analysis is presented from which a numerical model is developed and is used to predict the crosstalk performance of a typical amplifier. Experimental results, using two separate signals within the gain band, show good agreement between measurement and theory, indicating that it is unlikely that crosstalk will present a problem in anticipated amplifier applications. From the measured crosstalk, an upper limit is placed on the lower level lifetime, indicating that the population of this level will have a negligible effect amplifier gain. A novel technique for measuring the upper state lifetime in an amplifier, based on pump power dependence of crosstalk, is described and experimental results which are in agreement with fluorescent decay are presented     

Fabrication of fluoride glass single-mode fibers

Single-mode optical fibers are obtained using ZrF4-based fluoride glasses. The fibers are drawn from a preform and jacketing tube. The preform with cladding/core ratio of 5.1 is made by using a built-in casting method. The cutoff wavelength of the fiber is experimentally determined to be 2.7 μm by bending loss measurement. Minimum transmission loss of the obtained fiber is 160 dB/km at a wavelength of 3.28 μm. TheV-value at this wavelength is estimated to be 2.03 from the core diameter and the refractive index difference.     

Tunable Pr/sup 3+/-Yb/sup 3+/-doped all-fiber upconversion laser

Fiber lasers in the visible spectral range at 603 and 634 nm were demonstrated using upconversion in fluoride Pr/sup 3+/-Yb/sup 3+/-doped fibers and Bragg gratings photoinduced in germanosilicate fibers. Reliable fine tuning of the all-fiber laser over 6.9 at 603 nm has been demonstrated using high strength fiber Bragg gratings.     

Visible fiber lasers excited by GaN laser diodes

This paper describes and discusses visible fiber lasers that are excited by GaN laser diodes. One of the attractive points of visible light is that the human eye is sensitive to it between 400 and 700 nm, and therefore we can see applications in display technology. Of course, many other applications exist. First, we briefly review previously developed visible lasers in the gas, liquid, and solid-state phases and describe the history of primary solid-state visible laser research by focusing on rare-earth doped fluoride media, including glasses and crystals, to clarify the differences and the merits of primary solid-state visible lasers. We also demonstrate over 1 W operation of a Pr:WPFG fiber laser due to high-power GaN laser diodes and low-loss optical fibers (0.1 dB/m) made by waterproof fluoride glasses. This new optical fiber glass is based on an AlF₃ system fluoride glass, and its waterproof property is much better than the well known fluoride glass of ZBLAN.     

2～5μm超长波段红外光纤通信的发展

评述了新的光纤通信,特别是长距离光纤通信的发展,这种光纤通信是基于超低损耗的氟化物玻璃纤维;讨论了氟化物玻璃纤维的进展和存在的问题;报道了我国应用于红外光纤通信的氟化物玻璃纤维、半导体激光器以及其它元件的研究结果;分析了长距离无中继的光纤通信的可能性。     

Gain and output-saturation limit evaluation in Pr/sup 3+/-doped fluoride fiber amplifier operating in the 1.3 mu m band

The optical amplification characteristics in a Pr/sup 3+/-doped fluoride fiber have been demonstrated. The amplification band in a Pr/sup 3+/-doped fluoride fiber fully covers the 1.3 mu m telecommunication window, and a practical optical gain value of over 13 dB was obtained. Moreover, a saturation power of +9 dBm was attained. If the problems of pumping efficiency and wavelength are solved, Pr/sup 3+/-doped fluoride fiber will become available for 1.3 mu m booster amplifiers.<>