Mode locked figure eight lasers

The figure eight laser (F8L) by the nature of its design provides the possibility for an intensity dependent element inside the cavity. It is this element which allows the laser to self-modelock, producing pulses as short as 90 fs. The laser is a special case of the additive pulse modelocked laser, hut operates in a regime where most of the analysis for that laser breaks down, namely, large changes in the pulse in one round trip. For these reasons much effort has gone into the study of the figure eight fiber laser since it was first introduced in 1990. The overall design of the laser is that of a ring cavity with a Sagnac interferometer incorporated in the cavity. This gives the laser the characteristic shape with one loop the Sagnac interferometer, and the other loop the ring laser