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标题: [求助]关于光通信的中英文对照的资料哪里找？ [查看完整版帖子] [打印本页]

时间: 2007-6-1 09:05

作者: jellyma 标题: [求助]关于光通信的中英文对照的资料哪里找？

不知道咱论坛里的英文资料都在哪？找不到，希望各位大侠给于帮助，给小弟些中英文对照的关于光通信的资料，不胜感激！

[此贴子已经被作者于2007-6-1 9:06:32编辑过]

时间: 2007-6-8 21:08

作者: jellyma

我自己做沙发，偷着乐！！！WDMEven visionaries such as Albert Einstein and Isaac Newton, who contributed significantly to our understanding of the properties of light and its fundamental importance, would not likely imagine the communications networks today. Highways of light span the globe, transmitting massive amounts of information in the twinkling of an eye. The equivalent of millions of telephone calls are transmitted on a single fiber, thinner than a human hair. Astounding as these advances may seem, we are only at the beginning of what is possible.   The current explosion of traffic in the worldwide networks is ample evidence of the speed with which we are well-documented phenomena. No matter what application it is that is generating traffic, most of this traffic will be carried by the unifying optical layer. For this reason, the growth of various applications such as telephony (whether cellular of fixed), Internet, video transmission, computer communication and database access leads directly to an increase in the demand placed on the optical network. It is very likely that the optical network will be used convey large amounts of video information in the future.   The most striking recent advance in optical networking have taken place in the field of Wavelength Division Multiplexing (WDM). These advances have benefited both terrestrial and submarine system, increased available capacities by several orders of magnitude and, correspondingly, reduced costs.   Until quite recently, it was possible to send only one wavelength, or color, of light along each fiber. A lot of effort has therefore been concentrated in maximizing the amount of information that can be transmitted using a single wavelength. Commercial systems will soon be able to carry 40Gbit/s on a single wavelength, while in the labs 320Gbit/s systems have already been demonstrated.   WDM, on the other hand, makes it possible to transmit a large number of wavelengths using the same fiber, effectively sending a “rainbow” of colors, where there was only one color before. Already today, commercially available systems can transmit 400Gbit/s of information on a single fiber. That is equivalent to transmitting approximately 200 feature-length films per second. Recently, a team of researchers from Bell Labs demonstrated long-distance, error-free transmission of 3.28Tbit/s over a single optical fiber.   The major advance that has led to the WDM revolution has been the invention of the Optical Amplifier (OA). Before the invention of the OA, after having traveled down a fiber for some distance, each individual wavelength had to be converted into electronic form, then back into optical form and then retransmitted into the next span of fiber. This was relatively expensive, since the optical components involved are highly specialized devices. The OA, however, can boost the signal power of all wavelengths in the fiber, thus eliminating the need for separate regenerators, and allowing many wavelengths to share the same fiber. Advances in optical amplifier design have been considerable. First, the operating window has expanded from 12nm, in the first generation, to about 80nm today. This allows the OA to amplify more signals simultaneously. Second, the development of gain equalization techniques has enabled a much flatter response and allows a number of these amplifiers to be connected in series. There have also been advances in the fibers themselves. In the early days of optical systems, optical fibers were not built for multi-wavelength transmission. Today’s fibers, on the other hand, are designed to have wide transmission windows and are optimized fir high-capacity, multiple-wavelength transmission.   The growing demand on optical network is a complex issue. On the one hand, the growth in capacity demand is extraordinary, and this in itself would be a big enough challenge to meet. However, this is accompanied by an increasing variety of services and application, as well as much more exacting requirements for quality differentiation. For example, there is quite a difference in the quality requirement for a signal being used to transmit an emergency telephone call or live video coverage of a medical operation, as compared with an E-mail that is not urgent and can arrive after several hours.   However, the same optical infrastructure is expected to support this wide variety of serviced. Internet protocol (IP) traffic, in particular, is growing exponentially. In some parts of the world, it is expected that IP will constitute the majority of traffic in the near future. Therefore, existing networks will have to be progressively optimized to handle various types of traffic. WDM has a major advantage in this regard, which is that the different types of traffic can be assigned to different wavelengths, as required.   Fortunately, we will soon be in a position to route individual wavelengths flexibly through an optical network. Features such as add/drop and cross-connection in the optical domain are being made possible by advance in photonics. I would like to draw attention to a few recent advances in this area. Firstly, the so-called digital wrapper is in the process of being standardized in the international bodies. A second significant development is the all-optical cross-connect. Bell Labs has recently unveiled its all-optical cross connect called the Lambda Router. Based on Micro Electro Mechanical Switching (MEMS) technology, it consists of microscopic mirrors that tilt, and thus re-direct optical signals. It is a such technology that will enable us to build networks that are purely optical. As more routing functions are implemented in the optical plane, more sophisticated intelligence is needed to control and manage the network. Control systems are being developed for these optical routers with which it will be able to build optical networks that can be easily configured in response to demand, and which also have self-healing properties and fast restoration times in the order of fifty to a hundred milliseconds, much the same as today’s SDH and SONET networks.   A further aspect to consider is access to the optical network. Most users would like to have direct access to the optical network and the enormous capacity it provides. This will take place in stages. Multi-wavelength optical systems are rapidly spreading out from the core towards the end user. In regional and metropolitan areas, the requirements are somewhat different from the long-distance area. The dream of Fiber To The Home (FTTH) or desktop is yet to materialize, mainly because of the cost-sensitive nature of this part os the network. In the near future, residential access may remain copper-based, using technologies such as ADSL to boost the capacity of traditional copper lines. However, for business offices, optical technology will be used to bring bandwidth to the end-used. Currently, a lot of Fiber To The Building (FTTB) networks are being deployed involving ATM and SDH access equipment at customer premises. The next step is to use WDM technology for these applications. WDM will first be used in industrial and campus Local Area Network (LAN) environments.   We are at the beginning of a revolution in communications networks, where increasing capacity, variety of applications, and quality of service are placing enormous demands on the optical network. The revolution of optical network is just beginning, and is advancing very swiftly towards a future online world in which bandwidth is essentially unlimited, reliable and low-cost.

[此贴子已经被作者于2007-6-8 21:12:09编辑过]

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