【正文】 longdistance and highdemand , infrastructure development within cities was relatively difficult and timeconsuming, and fiberoptic systems were plex and expensive to install and to these difficulties, fiberoptic munication systems have primarily been installed in longdistance applications, where they can be used to their full transmission capacity, offsetting the increased 2000, the prices for fiberoptic munications have dropped price for rolling out fiber to the home has currently bee more costeffective than that of rolling out a copper based have dropped to $850 per subscriber in the US and lower in countries like The Netherlands, where digging costs are 1990, when opticalamplification systems became mercially available, the telemunications industry has laid a vast network of intercity and transoceanic fiber munication 2002, an intercontinental network of 250,000 km of submarine munications cablewith a capacity of Tb/s was pleted, and although specific network capacities are privileged information, telemunications investment reports indicate that network capacity has increased dramatically since In 1966 Charles and George hockom proposed optical fibers at STC Laboratories(STL)at Harlow, England, when they showed that the losses of 1000 dB/km in existing glass(pared to 510 db/km in coaxial cable)was due to contaminants, which could potentially be fiber was successfully developed in 1970 by Corning Glass Works, with attenuation low enough for munication purposes(about 20dB/km), and at the same time GaAs semiconductor lasers were developed that were pact and therefore suitable for transmitting light through fiber optic cables for long a period of research starting from 1975, the first mercial fiberoptic munications system was developed, which operated at a wavelength around 181。m and used GaAs semiconductor firstgeneration system operated at a bit rate of 45 Mbps with repeater spacing of up to 10 on 22 April, 1977, General Telephone and Electronics sent the first live telephone traffic through fiber optics at a 6 Mbit/s throughput in Long Beach, second generation of fiberoptic munication was developed for mercial use in the early 1980s, operated at 181。m, and used InGaAsP semiconductor these systems were initially limited by dispersion, in 1981 the singlemode fiber was revealed to greatly improve system 1987, these systems were operating at bit rates of up to Gb/s with repeater spacing up to 50 first transatlantic telephone cable to use optical fiber was TAT8, based on Desurvire optimized laser amplification went into operation in fiberoptic systems operated at 181。m and had losses of about dB/ achieved this despite earlier difficulties with pulsespreading at that wavelength using conventional InGaAsP semiconductor overcame this difficulty by using dispersionshifted fibers designed to have minimal dispersion at 181。m or by limiting the laser spectrum to a single longitudinal developments eventually allowed thirdgeneration systems to operate mercially at Gbit/s with repeater spacing in excess of fourth generation of fiberoptic munication systems used optical amplification to reduce the need for repeaters and wavelengthdivision multiplexing to increase data two improvements caused a revolution that resulted in the doubling of system capacity every 6 months starting in 1992 until a bit rate of 10 Tb/s was reached by , bitrates of up to 14 Tbit/s have been reached over a single 160 km line using optical focus of development for the fifth generation of fiberoptic munications is on extending the wavelength range over which a WDM system can conventional wavelength window, known as the C band, covers the wavelength range 181。m, and the new dry fiber has a lowloss window promising an extension of that range to developments include the concept of “optical solitons, “ pulses that preserve their shape by counteracting the effects of dispersion with the nonlinear effectsof the fiber by using pulses of a specific the late 1990s through 2000, industry promoters, and research panies such as KMI and RHK predicted vast increases in demand for munications bandwidth due to increased use of the Internet, and mercialization of various bandwidthintensive consumer services, such as video on protocoldata traffic was increasing exponentially, at a faster rate than integrated circuit plexity had increased under Moore’s the bust of the dot bubble through 2006, however, the main trend in the industry has been consolidation of firms and offshoring of manufacturing to reduce , panies such as Verizon and ATamp。T have taken advantage of fiberoptic munications to deliver a variety of highthroughput data and broadband services to consumers’ homes.