Defect mediated turbulence in a long laser

摘要

In this paper, we experimentally and theoretically analyse the formation and interaction of dark solitons in a long laser. The laser includes a semiconductor optical amplifier (SOA), centred around 1300nm, an intracavity filter and a fibre cavity whose length can vary from 20m to 20km. Near the lasing threshold the laser exhibits slowly evolving power dropouts the circulate the cavity. These dropouts are associated with the formation of Nozaki-Bekki Holes (NBH), also referred to as dark solitons. We observe both experimentally and numerically that the core of these holes exhibit chaotic dynamics and emit short light pulses. These pulses are found to be blue shifted with respect to the frequency of the dark solitons and therefore travel with a faster group velocity. These pulses are strongly damped, as they are detuned with respect to the filter transmission, but they may lead to the creation of new dark solitons. These pulses also play a major role in the development of optical turbulence when the filter is set at a frequency above 1310nm. In this case, the laser displays numerous dark solitons per round trip and the fast travelling pulses act as an interaction between the solitons, which can lead to the development of defect mediated turbulence.