Reverse horseshoe and spiral templates in an erbium-doped fiber laser

Time series obtained from the emission of an erbium-doped fiber ring laser with sine-wave pump modulation have been analyzed in order to determine the topological structure of the underlying chaotic attractor. With appropriate modulation conditions, topological structures not often observed in experimental systems have been found: the reverse horseshoe and the spiral template. The method employed for template determination is not conventional as it takes profit of the high dissipation of the system, which allows one to simplify dramatically the general procedure of analysis.