Data Transmission via Glass Fibre

Nowadays, world wide communication is based on fibre optics combined with laser diodes and the development in this area is amongst to the most exciting ones in this century. In principle this new technology does not require a new understanding of physics because the related phenomena are well known and can be considered as a combination of classical optics and lasers. However, for realisation a lot of technical problems had to been solved. In the fibres mainly used in communication, the light is guided within a „glass tunnel“ with a diameter of only 5 µm. The necessary mechanical components as well as the production process of the fibres themselves were the subject of comprehensive developments in the past. Meanwhile, the traditional copper wire lines will be substituted world-wide by optical fibres due to their outstanding technical as well as economical superiority. Within this project, a data transmission segment will be set-up with a fibre length of 5 km and the transmission of video as well as audio signals are studied. The project starts with the connection of the fibres to the transmitter and receiver. In the next step, the electronical connections are made. The set-up comes with a colour CCD video camera and a CD - Player as an audio source and a TV screen as a monitor. This project demonstrates in an impressive way the new exiting telecommunication via optical glass fibre, the technology for today and tomorrow.

Principle of operation

The video signal of the CCD camera (CCD) is fed to the high speed modulator (HSM) of the diodelaser (LD) which is mounted into the same housing of the laserdiode in order to achieve the highest possible bandwidth. The light of the laserdiode is collimated by the optics (C1) and focused by means of (L1) into the 5000 m long multimode fibre. The laser light at the exit of the fibre is focused by means of the lens (L2) onto the sensitive area of a high speed Si PIN photodiode from where it is fed to the amplifier unit (HSA). A video monitor is used to display the transmitted video as well as the audio signal when the provided CD player is used.