光纤通信RF方面的中英文翻译

RF和微波光纤设计指引

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RF and Microwave Fiber-Optic Design Guide

Agere Systems Inc., through its predecessors, began developing and producing lasers and detectors for linear fiber-optic links nearly two decades ago. Over time, these optoelectronic components have been continually refined for integration into a variety of systems that require high fidelity, high frequency, or long-distance transportation of analog and digital signals. As a result of this widespread use and development, by the late 1980s, these link products were routinely being treated as standard RF and microwave components in many different applications.

There are several notable advantages of fiber optics that have led to its increasing use. The most immediate benefit of fiber optics is its low loss. With less than 0.4 dB/km of optical attenuation, fiber-optic links send signals tens of kilometers and still maintain nearly the original quality of the input.

The low fiber loss is also independent of frequency for most practical systems. With laser and detector speeds up to 18 GHz, links can send high-frequency signals in their original form without the need to downconvert or digitize them for the transmission portion of a system. As a result, signal conversion equipment can be placed in convenient locations or even eliminated altogether, which often leads to significant cost and maintenance

savings.

Savings are also realized due to the mechanical flexibility and lightweight fiber-optic cable, approximately 1/25 the weight of waveguide and 1/10 that of coax. Many transmission lines can be fed through small conduits, allowing for high signal rates without investing in expensive architectural supports. The placement of fiber cable is further simplified by the natural immunity of optical fiber to electromagnetic interference (EMI). Not only can large numbers of fibers be tightly bundled with power cables, they also provide a uniquely secure and electrically isolated transmission path.

The general advantages of fiber-optics first led to their widespread use in long-haul digital telecommunications. In the most basic form of fiber-optic communications, light from a semiconductor laser or LED is switched on and off to send digitally coded information through a fiber to a photodiode receiver.

By comparison, in linear fiber-optic systems developed by Lucent, the light sent through the fiber has an intensity directly related to the input electrical current. While this places extra requirements on the quality of the lasers and photodiodes, it has been

essential in many applications to transmit arbitrary RF and microwave signals. As a result, tens of thousands of Agere Systems’ transmitters are currently in use.

The information offered here examines the basic link components, provides an overview of design calculations related to gain, bandwidth, noise, and dynamic range

and distortion. A section on fiber-optic components discusses a number of key parameters, among them wavelength and loss, dispersion, reflections, and polarization and attenuation. Additional information evaluates optical isolators, distributed-feedback lasers and Fabry-

Perot lasers, predistortion, and short- vs. long-wavelength transmission.

One of linear optical fiber relation main usages or receives between the electronic installation and the remote localization antenna in the transmission transmits RF and the microwave signal。Because of the optical fiber chain flexibility，possibly can for the simulation or digital signal design some antennas，including the military and the commercial communications satellite，the global localization satellite，the remote sensing with traces the lighthouse，or wireless cell network 。Another kind of type chain is the optical fiber delay line，installs in a package it including a transmitter，a receiver，with long textile fiber。It may provide the long delay time, high band width, with low weight.

These high-frequency RF and the microwave product has obtained benefits from the use linear optical fiber equipment cable television raging tide middle earth. In here, the textile fiber expands the TV signal the transmitting range, improves their quality and the system reliability, but when merely only has the electric cable, even with the system which used compares has saved the expense

In each of these applications, as well as many others, the Agere Systems’ transmitters and receivers comprising the links are similar and can be treated as standard microwave components. Focusing on these common elements, this design guide describes the general technical considerations and equations necessary for engineers to choose the most appropriate Agere Systems’ components for their systems. These equations also have been incorporated into various programs, which an Agere Systems’ applications engineer can use to provide an analysis for a specific link application.

Figure 1 shows the three primary components in a fiber-optic link: an optical transmitter, a fiber-optic cable, and an optical receiver. In the transmitter, the input signal modulates the light output from a semiconductor laser diode, which is then focussed into a fiber-optic cable. This fiber carries the modulated optical signal to the receiver, which then reconverts the optical signal back to the original electrical RF signal.

RF和微波光纤设计指引

大概二十年以前，Agere系统公司通过其前辈开始发展和生产激光和检测器线性光纤的联系。这些电子元件组成部分连续不断地为了进入各种各样要求高保真，高频率，或者长途模拟和数字的信号的运输的系统。由于这广泛传播的使用和发展，八十年代末，这些系列产品通常被认为是标准的RF和微波组成部分不同的应用。

光纤的许多引人注意的优势使它被越来越广泛的应用。光纤设备的最主要的好处是其损失低。由于光的减弱的小于0.4 dB每公里，光纤传送的信号几乎可以传输数十公里并且仍然保持原来的输入的质量。

对于最实际的系统低的纤维损失也是独立的频率。用激光和检测器加速到18 GHz，联系能以他们原来的形式发送高频信号，无须改变或者为了一个系统的传输部分使他们数字化。因此，信号转化设备便可以闲置或者干脆不用，这样便可以节省一部分费用。

机械的灵活性节省了费用，同时，轻量级光纤电缆，大约只有1/25波导的重量的1/10coax。考虑到高的信号速率没有昂贵的建筑投资方面的支持。许多传播线能通过小的导管支持。光缆的布局更进一步被光纤的自然免疫性简化到电磁的干扰( EMI )。不仅数目大的纤维能用电源电缆严紧地捆扎，他们也提供了一个独一的安全和电气隔离的传输路径。

纤维光学设备的巨大的优势首先使得他们在长的拖曳数字电讯中的广泛传播中被使用。按光纤通信的最基本的形式，从一种半导体激光器发射的光或者发光二极管发射的光通过一种纤维发送数字编码的信息到一个光电二极管。

通过比较，在线性的纤维光学系统中发展朗讯，光通过纤维发送的强度直接与输入的电流有关。然而这就对激光和光电二极管的质量有额外的要求，它在许多传送专断RF和微波信号应用中很重要。因此，目前有成千上万的Agere系统的传输器在被使用。

信息在这里提供检查基本的联系组成部分，与提供设计计算的一种综述与增益，带宽，噪音，动态的范围和失真有关。在光纤上的一段组成部分讨论一些主要参数，有波长，损失，弥散，反射，和极化和衰减。附加的信息评价光学隔离者，分发反馈激光和Fabry-Perot激光，和短的和长的波长传输。

线性的光纤的联系的主要的用法之一在传送或者收到电子设备和遥远的定位天线之间发送RF和微波信号。因为光纤链的灵活性，可能会为模拟或者数字的信号设计一些天线，包括军方和商业通信卫星，全球的定位卫星，遥感与追踪灯塔，或者无线细胞网络。另一种类型的链是光纤延迟线，装在一个包里的它包括一台传输器，一个接收器，和一个长的纤维。它可以提供长的延迟时间，高带宽，和低重量。

这些更高频率的RF和微波产品已从使用线性的光纤设备电缆电视的狂潮中间接地获益。在这里，纤维扩展TV信号的传输距离，改进他们的质量和系统可靠性，而当仅仅只有电缆时，甚至与采用的系统相比节省了费用。

在每个这样的应用中，还有许多其他的，Agere系统的传输器和接收器包括

一些链可以类似被对待为微波组成的标准部分。

注意这些普通的组件，这个设计指南描述了一些必要的技术考虑和方程，可以让工程师选择最适宜他们的系统的组成部分。这些方程也在各种各样计划中被使用，这样一名Agere 系统应用工程师就能通过它来为具体的联系应用提供一种分析。

一种光纤链中三个主要的组成部分：一台光学的传输器，一个纤维光学电缆，和一个光学的接收器。在传输器中，输入信号从一半导体激光二极管中输出，然后聚焦到一光缆中。

光纤把调节的光学的信号载送到接收器，然后使光学的信号恢复为原始的电子RF 信号。