中英论文翻译对照塑料光纤传光原理通信大学论文.doc

---塑料光纤传光原理通信

塑料光纤传光原理通信
1． 前言
光纤自身不能发光，但光纤可以传光，用于照明；光纤照明所选用的光纤，按照光纤材质的不同，通常可分为石英光纤、多组分玻璃光纤和塑料光纤POF等，本文主要介绍POF的传光原理，其它的光纤传光原理同POF的传光原理是一致的。
光在透明柱体中通过多次全反射向前传播的现象，他们就是古代的玻璃吹制艺人。而首次科学阐述这一现象的，却是英国皇家学会的约翰·丁达尔向英国皇家学会演示了一个著名的实验，他当时用一只盛满水的器皿，让水从器皿的侧孔中流出，这时投射在水中的光也随着水流传导出来。
1880年，威廉·惠勒(William Wheeler)提出“管道照明”的设想，并获得美国专利，这是有案可查的最早的“遥控照明”装置，其基本原理是：用内壁涂有反射层的管子把中心光源的光象自来水一样引至若干个需要照明的地点, 这实际上是光纤用于照明的雏形，光纤照明系统简单地就可以看作是和上述的“管道系统”相类似的一个系统，在这个系统中，所传输的介质是光，而用以传输光的“管道”就是光纤，光纤可以把光线从光源处传输至需要照明的特定区域。1954年，《自然》杂志发表了Hopkin's 和Kapany成功地用一束10,000到20,000 的纤维来传输图像的文章,Van Heel发现低折射率光纤包层的作用，纤维的图像传输的成功实现和光纤包层的提出这两个进步标志着光导纤维作为一个新兴学科的诞生, 1966年,英国标准电信研究所英籍华裔科学家高锟(K.C.Kao)博士和G.A.Hockham 在详细研究了玻璃的传输损耗后,撰写的文章《用于光频的介质纤维表面波导》发表在伦敦电气工程师协会（IEE）会刊上，他们从理论上指出:如果减少或消除光导纤维中的有害杂质如过渡金属离子，可大大降低光纤传输损耗, 提高光纤的传光能力，从而推动了光纤制造工艺的研究。美国杜邦DuPont公司亦在这一年向市场推出了世界上第一根POF[1]，POF就是光纤的一种,而光纤用于光纤照明的基本原理是利用光线在不同折射率介质的界面发生全反射，实现光在光纤中的高效传输以及光纤与光源的充分耦合，并通过与各种光学元件的组合，达到需要的照明效果，为了解光在光纤中的传输方式,现介绍子午光线在POF中的传输特性。
2． 光的基础知识
　　光是通过光源内大量的分子或原子振动而产生的辐射。1894年，麦克斯韦从理论上指出，光是一种电磁波，1905年爱因斯坦提出光是一粒一粒的粒子流，每个粒子可被称为光子。也就是说光既具有粒子性，又具有波动性，光在传播时表现为波动性，而与物质作用时又表现为粒子性。通常我们所说的光是电磁波的一种，它通常由紫外光、可见光和近红外光组成，其中1-390nm 波段的光为紫外光UV，波长为280-300nm波段为UV-B，它的强光可以杀死或严重损伤地球上的生物;200-280um波段为UV-C，它的强光可以杀死地球上一切生物，包括人类, 比紫外光频率更高的还有X光和γ射线等; 390-760nm波段的光为可见光；波长在760-1500nm为近红外光，中红外波段波长范围为1.5-25μm，远红外光谱波长范围25-300μm,比远红外光频率更小或波长更长的有毫米波、微波、短波、中波和长波等。而可见光又是由七色光组成的，即可见光含有红色光、橙色光、黄色光、绿色光、蓝色光和靛青光等色光
国际照明委员会统一规定的标准是：选水银光谱中波长为700nm的红光为红基色光， 波长为546.1nm的绿光为绿基色光, 波长为435.8nm的蓝光为蓝基色光。常规POF一般在紫外光波段并没有很好的透光性，而石英光纤和特制的液芯光纤在这一区域有很好的透光率，POF在可见光区域有很好的透光率，由POF芯材选用氟化和氘化聚合物材料制备的POF在近红外光区域才有很好的透光率。
光在真空中的传播速度是最快的，传输介质不同，其折射率不同，传光速度也不同。相对而言，折射率大的传输介质是光密介质，折射率小的传输介质是光疏介质，对于POF而言，POF芯材为光密介质，POF皮材为光疏介质，由于光在光密媒介－芯材中的传播速度会降低，故光在芯材中的传输速度慢于皮材中的传输速度;在空气中，由于n≈1，光波的传播速度接近于真空中的传播速度C；纯PMMA的折射率为1.49,故光在其中的传输速度约为2.01×108m/s。
光在均匀媒质或不均匀媒质中传输时，满足费玛(Fermat) 原理，即光从空间一点到另一点是沿着时间为极值的路程而传播的，即光沿着光程为最小或最大或恒量的路径传播。
3.POF传光原理
荧光POF就是在POF芯材中掺入一定量的荧光剂制备而成的POF，这种POF经过特定波长的光照射后，将发出特定波长的光，其原理比较复杂，可简单认为基态分子中成键电子吸收光后激发，然后单线态分子返回到基态，即发出荧光。荧光POF 按折射率分布结构分类，可分为荧光SI POF 和荧光GI POF，掺杂有机染料的POFA最重要特性是在宽波长范围内提供高功率输出。荧光POF的传光原理示意图如下，它满足一般的SI 型光纤的传光特性，但入射光的波长不同于出射光的波长。
荧光POF还有另一种传光方式，这就是入射光可从侧面照射荧光POF，出射光从光纤两端面出射，当然入射光的波长不同于出射光的传输波长。荧光材料的光特性主要依赖于基质材料，荧光POF增益放大特性同泵浦波长、荧光POF长度及所用掺杂剂和浓度有关。所谓增益G是指POF输出信号光功率Pout与输入光功率Pin之间的一种比值。
4.结束语
POF之以能传光是因为光纤具有芯皮结构，光在POF中传输是按全反射原理进行传光的，光在SI POF中的传输方式为全反射式锯齿型，光在GI POF中的传输方式为正弦曲线型；同时为了简化计算，选用子午线进行了参数计算，子午线就是光线的传播路径始终经过光纤轴并在同一平面内，这些参数计算包括最大入射角或发射光角度、数值孔径、子午线在阶跃型光纤中的几何行程及反射次数；侧面发光POF和荧光POF也是按全反射原理进行传光的，对于单芯侧面发光POF多是由非固有损耗导致侧面发光，而对于多芯侧面发光POF则是由弯曲损耗产生侧面发光的。荧光POF经过特定波长光激发后发出特定波长的光，而且激发光不仅可从端面入射，而且可从侧面入射。

Principles of Plastic Optical Fiber Communication
Optical Communication
1. Preface
Fiber itself is not light, but can return optical fiber for illumination; fiber optic lighting, the choice of optical fiber, optical fiber materials according to different, often can be divided into quartz fiber, multi-component glass fiber and plastic optical fiber POF, etc. This paper introduces POF principle of the transmission of light, the other optical fiber transmission principles with the transmission of light POF principle is the same.
Perceives light in a transparent cylinder in the forward propagation through multiple total reflection phenomenon, they are the ancient glass-blowing artists. The first described the phenomenon of science, but it is the Royal Society, John • Tyndall demonstrated to the British Royal Society, a famous experiment, he was filled with a water vessel, so that water from the vessel's side of the hole out, when the light is projected on the water with the water transfer out.
In 1880, William • Wheeler that "light pipe" scenario, and the U.S. patent, which is the earliest documented "remote lighting" device, whose basic principle is: the inner wall coated with a reflective layer center of the tube to the same light source as tap water lead to a number of locations the need for lighting, which is actually the prototype of fiber used for lighting, fiber optic lighting systems can be seen as a simple and above "pipeline system" similar to a system, in this system, the transmission medium is light, and to transmit light of the "pipeline" is the optical fiber, optical fiber can transmit light from the light source to the need for lighting a specific area. 1954, "Nature" magazine published a Hopkin's and Kapany successfully with 10,000 to 20,000 of the fiber bundle to transmit images of the article, Van Heel low refractive index cladding that the role of image transmission fiber and the fiber to achieve success layer optical fiber made marked progress in these two subjects as the birth of a new, 1966, the British Standards Institute British Telecom Chinese scientist Charles KCKao and Dr GAHockham detailed study of the glass in the transmission loss, the article "for the optical frequency of the Dielectric fiber surface waveguides," published in the London Electrical Engineers (IEE) journal, they theoretically pointed out: If the optical fiber in the reduction or elimination of harmful impurities such as transition metal ions can greatly reduce the transmission loss and improve the optical fiber transmission capacity, thus promoting the study of optical fiber manufacturing process. DuPont DuPont is also the year the company launched the world's first to market a POF [1], POF is an optical fiber, and fiber optic fiber optic lighting for the basic principle is to use light in the interface of different refractive index total reflection, to achieve high optical transmission in optical fibers and optical fiber coupled with a sufficient light source, and through a combination with a variety of optical components to achieve the desired lighting effects, to understand the transmission of light in fiber mode, are presented in the meridional ray POF in the transmission characteristics. 2. The basics of light
Light through the light source in a large number of molecular or atomic radiation generated vibration. In 1894, Maxwell theory that light is an electromagnetic wave, Einstein proposed in 1905 alone, a piece of particle flow, each particle can be called photons. That is both a particle nature of light, they are volatile, when the light showed in the dissemination of volatility, but the performance and matter for the particle nature of the role of Shiyou. Usually we are talking about a light wave, usually from the ultraviolet, visible and near infrared light, composed of 1-390nm wavelength UV light is UV, wavelength 280-300nm wavelength of UV-B, it light can kill or seriously damage life on Earth; 200-280um band for the UV-C, its light can kill all living things on Earth, including humans, there is a higher frequency than ultraviolet light and γ X rays; 390-760nm band of light to visible light; wavelength of 760-1500nm for the near-infrared light, the infrared wavelength range of 1.5-25μm, far infrared spectrum wavelength range 25-300μm, more than far-infrared optical frequency or wavelength smaller longer a millimeter wave, microwave, short wave, medium wave and long wave and so on. The visible light is again composed of seven colors, that contain visible red light, orange light, yellow light, green light, blue light and shade of indigo light, etc.
International Commission on Illumination uniform standard is required: select a wavelength of 700nm mercury spectrum in the red for the red-based color light, green light of a wavelength of 546.1nm base for the green shade, the blue wavelength of 435.8nm blue base shade. Conventional POF usually ultraviolet light is not very good, while quartz fiber and a special liquid-core optical fiber in the region has a good transmittance, POF in the visible region have very good light transmission rate, from POF core material selection and deuterium fluoride polymer material prepared POF in the near infrared region have a very good light transmission.
Propagation of light in vacuum is the fastest speed, transmission medium, its refractive index is different from the speed of light transmission is also different. In contrast, a large refractive index of light transmission medium is denser medium, the refractive index of the transmission medium is a little sparse optical media, in terms of the POF, POF core material for the optical denser medium, POF material for light skin thinning medium, the light optical density media - in the core material will reduce the propagation velocity, so the light transmission in the core material in the skin material slower than the transmission speed; in the air, due to n ≈ 1, close to the propagation velocity of light propagation in vacuum Speed C; the refractive index of pure PMMA is 1.49, so the light in which the transmission rate of about 2.01 × 108m / s.
Homogeneous or inhomogeneous medium light transmission medium to satisfy Fermat (Fermat) principle, that light from the space point to another along the time for extreme distance and spread, that is, the smallest of light along the optical path or the path of maximum or constant communication.
3.POF principle of light transmission
Fluorescent POF POF core material is mixed with a certain amount of fluorescent agent prepared from the POF, POF after such a specific wavelength of light irradiation, will send a specific wavelength of light, the principle is more complex, can be simply that the ground state molecule After bonding electron absorption of light excitation, and then return to the singlet ground state molecules that fluoresce. Refractive index distribution by fluorescence of structure POF can be divided into fluorescent SI POF and fluorescence GI POF, doped organic dye POFA most important feature is the wide range of wavelengths to provide high power output. Fluorescent POF schematic diagram of the transmission of light below, it meets the general fiber of the transmission SI optical properties, but different from the wavelength of incident light wavelength of light emitted.
Fluorescent light POF there is another way of transmission, which is irradiated from the side of the incident light can be fluorescent POF, the output beam emitted from the fiber surface at both ends, of course, the wavelength of incident light is different from the transmission wavelength of light emitted. Optical properties of fluorescent material mainly depends on the matrix material, the same fluorescence characteristics of POF gain amplification pump wavelength, fluorescence POF length and the amount of dopant and concentration. Gain G is called POF output signal power Pout to the input optical power ratio between a Pin.
4. Conclusion
POF can be passed just because of the fiber with the core structure of the skin, the light transmission of POF is based on principle of total reflection of light transmission, light transmission in the SI POF in the zigzag way for the total reflection type of light in the GI POF in the transmission mode is the sine curve type; the same time to simplify the calculation, the parameters used for calculation of Meridian, Meridian is the propagation path of light through the optical axis and is always in the same plane, the calculation of these parameters include the maximum angle of incidence or emission angle, numerical aperture, In the step-type fiber radial geometry and reflection travel times; side light and fluorescence POF POF is by total internal reflection of light transmission principle, for more than single-core POF side light loss caused by the side of non-natural light, and for multi-core side of the light bending loss POF is produced by the luminous side. After a specific wavelength of fluorescence excitation POF issued after a specific wavelength of light, and not only exciting light incident from the end, but also from the side of the ncident.