text12_WDN光网的.pptVIP

Technical English For Communication Engineering;WDM Optical Communication; As we enter the new millennium with exploding Internet traffic volume（爆发的网际网路流量）and limitless（无限的）business opportunities, it is natural to pause and think about how we are going to meet this challenge. Needless to say, there is no better known physical medium than fiber, and no signal source better than light to meet these new and emerging（新兴的）requirements. Therefore, as optical networking technology evolves（进化） from;megabits per second to gigabits per second to terabits per second, and soon to petabits per second, we should get really comfortable with the power of the exponents（指数）and what it means at the service level. Fortunately, we have a way（有办法）to go to reach the data transport limit of fiber. For example, with the current;state of device technology, a good laser source can emit（发射）106 photons/s, and a good detector, which can detect a bit with 10 photons, can get 1 Pb (105 p/s) on a single fiber. Nevertheless（虽然如此）, the device technology is going to get better with time, further pushing the limit of optical fiber capacity. Thus, fiber optics is a future-proof technology. ;With wavelength-division multiplexing (WDM：波分复用), it is now possible to transmit different colors of light over the same fiber, which has provided another dimension（维度）to increasing bandwidth capacity and channeling（分为多路）raw data capacity into smaller chunks（块）of bandwidth. This advance is akin to（类似于）a self-expanding;highway where you light another channel when the traffic load increases without laying（铺设）new fiber. Thus, WDM optical networks offer, among other capabilities, flexibility, scalability（可伸缩性）, and capacity. Current systems are capable of delivering 10 Gb/s/channel on an over-100-channel system. In addition to bandwidth increase, new technologies also enable more functionality（功能）in optics. ;If history is any indicator, these capabilities will only get better and richer in features（特性）. Optical