SMC - 09 Optical Transmitter and Receiver

Topics

Optical Fibre Transmitter
Optical Fibre Receiver
Optical Glass Fibre, 5 km
CCD Camera
Video & Audio Transfer via 5 km Optical Fibre
Optical Signal Detection
Fibre Coupled Photodetector
 

Basic Concept

Nowadays,  world-wide communication is based on fibre optics combined with laser diodes and the development in this area is amongst the most exciting 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 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 fibre due to their outstanding technical as well as economical superiority. Within this project, a data transmission segment will be set-up with a total fibre length of 5 km and the transmission of video and 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 done. The set-up can operate with a colour CCD video camera, a CD Player as an audio source, a TV screen as a monitor as well as serial RS232 data devices. This project demonstrates in an impressive way the new exiting telecommunication via optical glass fibre, the technology for today and tomorrow.

Experimental Set-up

The set-up consists of the base unit housing which provides all further slot-in modules with the required electrical power. The data transmission line consists of 5 segments of optical single mode fibres each having a length of 1 km. The electronic signal (video, audio or data) are fed into the optical transmitter where the conversion to laser light takes place. The optical output of the transmitter with a wavelength of 1.3 µm is connected via a fibre patch cable to the desired glass fibre segment. Depending on the goal of the investigation, the 5 fibre segments can be inter-connected also via fibre patch cables. A maximum distance of 5 km is achieved when all segments are connected in series which each other. The end of the fibre line is either patched to the provided InGaAs fibre coupled photodetector (PD) in order to measure or monitor the optical signal or it is connected to the optical receiver. Here, the back conversion to electronic signals takes place and the individual video, data or audio signal can be connected to a monitor, computer or audio system.
Due to the fact that a combination of 5 different lengths of the fibre line is available, reliable measurements of the attenuation can be carried out. For this purpose, the use of the frequency generator is recommended for a steady signal.