Principle of Operation

Fibre Laser are a special class of Lasers differing from the ��classic design��. The optical resonator consists of an optical fibre which can be coiled to a drum providing extreme long amplification lengths.
Within this experiment the students are introduced to the basics of optical pumping with subsequent application by means of an Erbium doped optical fibre (EDF). This type of fibre is commonly used as amplifier in long distance telecommunication as so called EDFA (Erbium doped Fibre Amplifier). Due to its particular properties the EDF is a promising candidate also as laser source for telecommunication. Furthermore it is also used as an active fibre laser gyroscope.
This experiment allows to study the EDF in a linear as well as ring configuration. As pump source a diodelaser emitting around 100 mW at a wavelength of 980 nm is applied. Via a wavelength division multiplexer (WDM) the pump light is coupled to the EDF. The other end of the EDF is connected to a beam expander which delivers a parallel light bundle which is coupled after a distance of 100 mm back into a patch fibre.
To close the ring this fibre is connected to the WDM. In common applications this ��free space�� propagating part is not used. However, for experimental purposes a variety of demonstrations can be done. By means of a thin glass plate - used as output coupler - a small fraction of the ring laser radiation is coupled out for further analysis. Herewith also counter propagating ring modes can be verified. Additional optical components can be inserted like passive q-switch, birefringent tuner etc. With the provided photo detector and the modulator the time response like spiking, life time of excited states can be studied