弯曲损耗减小的渐变折射率塑料光纤的波导参数设计

为了消除光纤的弯曲损耗，甚至是恶劣弯曲条件下的弯曲损耗，日本Keio大学的科研人员对渐变折射率塑料光纤（GI—POF）的波导结构，如折射率分布、数值孔径（NA）和芯径进行了适当设计。当芯径小于200μm、NA大于0．25时，GI—POF在恶劣弯曲条件下的弯曲损耗明显减小。当芯径为200μm、NA为0．24时，即使在恶劣弯曲条件下GI—POF的弯曲损耗也消失了。首次试验证实。由弯曲引起的模式耦合导致了弯曲损耗。光纤弯曲前的模式耦合强度对弯曲损耗有很大的影响。通过相邻模之间的传播常数差△β评定了模式耦合强度。随芯径和NA而变的△β影响弯曲损耗。因此，根据邸的计算结果，日本Keio大学的科研人员提出适当设计GI—POF的波导参数的指导性意见，以便抑制弯曲损耗。     

氘化渐变折射率聚合物光纤的制造工艺和光学性能

日本横滨Keio大学的科研人员提出一种将两步界面凝胶聚合工艺用于氚化聚合物材料、使其能在短距离网络中进行千兆比特以上数据传输的渐变折射率聚合物光纤（GI—POF）。采用这种工艺可以获得几乎最佳的折射率分布，具有良好的重复性。叙述了采用聚甲基丙烯酸甲酯（PMMA）包层制备氚化聚甲基丙烯酸甲酯（PMMA—d8）基GI—POF的情况。这表示，低损耗PM—MA-d8材料仅用于纤芯。因为包层仅传输一小部分的光功率，不需要用低损耗材料。已经证实．即使包层由氢化PMMA组成，PMMA-d8仍具有低的衰减。因此。采用PMMA—d8纤芯和PMMA包层的GI—POF能实现300m以上千兆比特数据传输，而这是普通PMMA基GI—POF无法实现的。     

涂覆法制作聚苯乙烯芯聚合物光纤工艺

阐述了溶液涂覆法生产苯乙烯（PS）芯聚合物光纤（POF）的工艺过程，其中皮材溶液可采用皮材和溶剂配制的方法制备，也可采用溶液聚合物的方法制备，POF皮层的形成可采用烘干和紫外固化工艺。并介绍了皮材单体的选择及溶剂，引发剂的浓度、聚合温度和氧气对皮材分子量及性能的影响。     

POF在三方面的最新进展

聚合物光纤（POF）和微结构POF（MPOF）分别是数据通信和不同类型传感器应用中“最后一百米”最有前途的解决方案。但为了进一步开发新型POF，需要在预制棒制造新工艺、新型光纤拉丝设备和POF的新应用三个方面进行研发。在POF拉丝过程中，采用普通电阻炉加热，沿预制棒径向会不可避免地产生大的温度升降。为了克服这一问题，开发出一种具有红外（IR）炉和普通电阻炉两种加热方法的新型加热炉。采用1．2μ波长的IR加热装置进行IR加热。因此，可以采用较大直径的预制棒并提高拉丝速度。制造出多个阶跃折射率新型预制棒用于开发工作。采用带有旋转管的车床装置进行预制棒制造。当观察到UV激活不足时，高效施加热激发径向聚合反应并对反应加以控制。通过在高温和高压下聚合预制棒芯使预制棒最终成型，由此获得的预制棒不需要缩棒。对POF深入细致的研究和开发包括两种标准折射率导引光纤以及用于激光器、放大器、非线性信号处理和生物光子应用的微结构POF。这样可以进一步扩展POF的有效应用范围。芬兰和丹麦的几位研究人员证明，此项研究工作是独创的，以前没有介绍或公布过。     

塑料光纤在裂缝监测中应用的可行性研究

针对普通石英光纤断裂应变较小在实际工程应 用中易发生断裂的问题,本文提出在结构裂缝监测 工作中运用塑料光纤(POF)代替普通石英光纤,设计了由光源、POF及光功率计组成 的塑料光纤裂 缝传感装置,并通过裂缝模拟装置对纤芯直径分别为0.25mm及0.5mm的POF在裂缝 监测中应用的可 行性进行了验证。实验结果表明,裂缝开度为0到6mm范围内,两种型号POF内部光 的强度随裂缝扩 展呈现逐渐减弱的变化,裂缝开展初期光强度变化明显,当裂缝宽度趋近于6mm时变化逐渐 减弱,符合理 论规律,且光纤直径较大时光强度变化更明显。因此POF可以有效感知裂缝的扩展 ,且光纤直径较大时对裂缝感知更敏感,将其应用在结构裂缝监测工作中是可行性的。     

近红外用高带宽渐变折射率聚合物光纤

1引言随着信息处理和传送需求的增长，光纤应用于高速信息传输日益增多．而在长距离传输系统中，单模玻璃光纤是最合适的传输媒质，这是由于它具有高带宽和高透明的特性。另一方面，同玻璃光纤相比，聚合物光纤（POF）具有芯径大、柔软性好、易于生产、处理且价格低等优点．近几年来，由于多队体的发展，人们的兴趣热点也集中在家庭、建筑物中的短距离高速信息传输中．POF因具备高带宽、低损耗的特性而应用于短距离信息传输中，而所有商用阶跃折射率（SI）型POF在100m的传输中其带宽仅有50MHz，这是由于它具有较大的模式色散．为了解…     

POF芯材中残留挥发性组分对其损耗的影响

随着通信技术的发展,视频和图像传输对网络宽带提出了更高的要求.塑料光纤(POF)由于线径较粗,使得光纤的接口成本得到降低.POF据此也被认为是解决"最后一公里"的最佳媒介.芯材PMMA树脂的纯度是影响POF损耗的关键因素.文章在PMMA树脂连续本体聚合制备技术的基础上,研究了纤芯树脂中挥发性组分含量对POF损耗的影响.     

HDPE-POF的选材与制作

光纤通信已经成为现代通信网络的主要方式.与传统通信方式相比,塑料光纤(POF)具有很多无可比拟的优点,因而,在很多领域都得到了广泛的应用.但是POF本身也有很多缺陷,为此研发了新的原材料以及新的光纤结构,使POF得到更广阔的发展空间.同时,还对制备光纤的一些实验设备进行了改进和更新,以利于研究的顺利进行.     

塑料光纤的技术发展及其应用

本文介绍了塑料光纤（POF）最重要的性能，包括POF的主要类型、制造及其目前和将来的应用，讨论了POF的带宽、误减特性及外部参数的影响。这些光纤可作为短距离通信链路用玻璃光纤的补充，因为它们易于加工、柔软且经济。由于这些优点，业已开发出不同的POF应用并已实用性，从用作简单的光传输波导作用作传感器和电信缆。本文全面介绍了POF。     

聚碳酸酯POF的拉制

主要介绍了聚碳酸酯(PC)塑料光纤(POF)拉制的情况.掌握了PC的性质及其软化温度.解决了光纤拉制过程中的许多问题,包括加热炉温度的控制、拉丝速度的控制、PC管应力的去除,以及预制棒的制作等.对拉制的光纤进行了分析并指出存在的问题,为PC- POF的拉制成功奠定了基础.     

塑料光纤预制棒折射率分布的测量

针对界面凝胶法制作的梯度折射率塑料光纤预制棒，提出了一种利用预制棒成像测量其折射率分布的方法，它是一种非破坏性测量。实验结果表明这种测量方法简单有效。     

Accurate refractive index profiling in a graded-index plastic optical fiber exceeding gigabit transmission rates

An optimum index profile offering the highest bit rate communication was formed in a poly methyl methacrylate (PMMA)-based graded-index plastic optical fiber (GI-POF) by modifying the polymerization process. The interfacial-gel polymerization process we have proposed to fabricate the PMMA-based GI-POF is capable of forming a nearly optimum refractive index profile. However, the theoretically calculated bandwidth from the measured index profile was reduced compared with a GI-POF with an optimum profile. In this paper, we report how to obtain a PMMA-based GI-POF having exactly the optimum index profile. The bandwidth of this ideal GI-POF was experimentally measured and a very high value of 2.88 GHz, even for a 150-m fiber length, was confirmed. The calculated bandwidth agreed well with the experimentally measured one. These results indicate that very low modal dispersion can be expected in a GI-POF fabricated by the modified interfacial-gel polymerization process.     

Fabrication process and optical properties of perdeuterated graded-index polymer optical fiber

We proposed a graded-index polymer optical fiber (GI-POF) enabling greater-than-gigabit data transmission in a short reach network by applying a two-step interfacial-gel polymerization process to a perdeuterated polymer material. Using this process, it is possible to fabricate a nearly optimum refractive-index profile with good reproducibility. In this paper, the preparation of a perdeuterated polymethyl methacrylate (PMMA-d8)-based GI-POF utilizing a PMMA cladding is described. This means that the low-loss PMMA-d8 material is used only for the core. Because the cladding transmits only a small fraction of the optical power, a low-loss material is not necessarily required for the cladding. It was verified that the low attenuation of the PMMA-d8 was maintained even if the cladding was composed of hydrogenated PMMA. As a result, a gigabit data transmission over 300 m was achieved by the PMMA-d8-core and PMMA-cladding GI-POF, which was impossible by the conventional PMMA-based GI-POF.     

梯度型塑料光纤棒制备工艺的研究

本文研究了通过界面凝胶聚合法制备折射率呈梯度型（GI）分布的塑料光纤棒,以溴苯（BB）作为高折射率掺杂单体。研究发现,在聚合反应前期,混合物在真空70℃的环境下聚合,而后期反应在高压气氛中进行,可以制备出没有任何真空泡和气泡的梯度型塑料光纤棒。     

Graded-index polymer optical fiber with high temperature and high humidity stability

It was clarified for the first time that the slight attenuation increment observed in the previous poly methyl methacrylate (PMMA)-dopant system graded-index polymer optical fiber (GI POF) we reported originated in the excess scattering loss induced by the aggregation of absorbed water into the POF. Although the PMMA material generally absorbs two weight% of water at maximum, the low attenuation of the conventional step-index (SI) POF whose core material is PMMA can be maintained at 70/spl deg/C, 80% relative humidity (RH) atmosphere because the absorbed water might be homogeneously dispersed without any aggregation in the core of POF. On the other hand, addition of dopant material having higher refractive index than that of PMMA is required to form the refractive index distribution in the GI POF, which decreases the amount of water absorption into polymer, because the dopant material is more hydrophobic than PMMA. Therefore, in spite of the small amount of absorbed water such as 0.5 wt.%, the absorbed water molecules can not be uniformly dispersed but must be aggregated to form heterogeneities in the refractive index of the polymer matrix. It was clarified that a dopant material that is as hydrophilic as PMMA was required to maintain the attenuation of the PMMA-dopant system GI POF under high temperature and high humidity atmosphere, and such a suitable dopant system GI POF was proposed.     

Large-core, high-bandwidth polymer optical fiber for near infrareduse

High bandwidth (more than 500 MHz·km) graded-index polymer optical fiber (GI POF) for near infra-red use was successfully fabricated by using partially fluorinated acrylate polymer. Since only three carbon-hydrogen bonds exist in a monomer unit, an absorption loss due to the stretching vibration of the carbon-hydrogen bond was remarkably reduced compared with the conventional POF's. The attenuation of the GI POF at 780-nm wavelength was 135 dB/km, which is much lower than that of the PMMA core POF (800 dB/km). The fluorinated polymer-based GI POF is satisfying a significant segment of high-speed multimedia network applications     

Thermally stable high-bandwidth graded-index polymer optical fiber

High-bandwidth poly (methyl methacrylate) PMMA base graded-index polymer optical fiber (GI POF) with high thermal stability is proposed. No distortion of bandwidth was observed even after more than 10000 hours aging at 85°C by selecting the large sized aromatic dopant which has a stable secondary interaction with PMMA matrix and maintains the high glass transition temperature (Tg) of the core of GI POF. The relationship between the heat-drawing condition from the GI preform to the fiber and the thermal stability in the attenuation was investigated. It was clarified that the length shrinkage of the fiber during the aging at high temperature caused large attenuation increase. On the other hand, the degree of shrinkage could be tightly controlled by changing the heat-drawing tension. It was confirmed that the GI POF drawn with optimized heat-drawing tension had no shrinkage of the fiber during aging at 70°C and no attenuation increase was observed     

塑料通信光纤

本文在阐述聚甲基丙烯酸甲酯芯和全氟化聚合物芯塑料光纤（POF）研究现状的基础上，评价了POF传输系统及其元器件、应用领域等问题。     

Theoretical investigation on the dispersion of graded-index polymeroptical fibers

Various experiments on polymer optical fibers (POF's) suggest that they present a large transmission capacity, but this is not confirmed by the standard theory. In this paper we present a full dispersion model based on evaluating the frequency response of the fiber instead of the direct calculation of the pulse broadening from the moments of the impulse response. The mathematical formalism is firstly displayed and subsequently applied to the graded-index POF made with polymethylmethacrylate (PMMA). The simulation results show that the baseband bandwidth is indeed enhanced due to the strong differential mode attenuation (DMA)     

Which is a more serious factor to the bandwidth of GI POF:differential mode attenuation or mode coupling?

It is clarified for the first time that the effect of the mode coupling on the bandwidth characteristic is very small in the graded-index polymer optical fiber (GI POF) compared with in the step-index (SI) POF. Although there have been several trials regarding the theoretical prediction of bandwidth characteristics of the GI POF, a disagreement between measured and estimated properties was observed. The origin of disagreement has been generally explained as the mode coupling effect. However, it is clarified in this paper that the effect of the differential mode attenuation is the dominant factor of disagreement between measured and predicted bandwidth characteristics, while the effect of the mode coupling is small. In order to clarify the reason why the calculated bandwidth characteristics of the GI POF show a disagreement with that measured, differential mode delay and differential mode attenuation were investigated. It was found that the highest order mode in the poly methyl methacrylate (PMMA) base GI POF attenuated 17 dB compared with the lowest order mode through 100-m transmission. By taking into account this differential mode attenuation, an excellent agreement is observed between calculated and measured results of both the bandwidth characteristics and group delay, in which no mode coupling was considered