Principle of Operation

The radiation of the green and red LED is launched to the plastic fibre PF by means of the Y coupler. The lens (L2) focuses the radiation which has passed the fibre onto the two photo detectors (PD1) and (PD2). The dichroic beam splitter (DBS) separates the two wavelength ranges (green and red) emitted by the LED. By independent modulation, the €žred€œ and €žgreen€œ channel of the LED two optical signals can be transferred via one fibre without crosstalk. The quality of the channel separation depends on the separation characteristic of the dichroic beam splitter.

The goal of this experimental system is to teach and train the handling and the signal transmission via optical plastic fibre. As a transmitter, a green and red LED is used to demonstrate independent dual wavelength data transmission in a single fibre. The radiation of the LED is coupled by means of a Y coupler into the fibre. The light at the exit of the fibre passes a dichroic beam splitter plate which is coated in such a way that the green radiation will be totally reflected whereas the red radiation is transmitted. Two photo detectors convert the light signal into electrical signals which are amplified by the receiver module and can be either displayed on a two channel oscilloscope or connected to two loudspeakers. The transmitter unit contains two independent drivers for both the LED as well as internal modulators. Other signal sources can be connected directly.