Introduction to the Congress Topic: On the Way to Optical Subscriber Lines

In a time period of only 25 years optical transmission systems based on the combination of laser diode, glass fiber and photo diode have experienced tremendous evolutionary steps and have reached a development stage which leads to the fact that for trunk lines such systems are more economical than the equivalent copper cable systems. Therefore only optical fiber systems are used for new installations in the trunk network. This is mainly due to the following two advantages of optical fiber transmission, namely low attenuation and large bandwidth. In addition to the application of optical fiber trunk lines the Deutsche Bundespost TELEKOM has installed a switched optical network VBN which gives connections between 29 German cities and therefore, allows to test new forms of broadband communication on a nationwide basis at a bitrate of 140 Mbit/s.