Sub-200-fs pulsed erbium-doped fiber laser using a carbon nanotube-polyvinylalcohol mode locker

Abstract

We study the difference in mode-locked operations of different saturable absorber films made of single wall carbon nanotube-polyvinylalcohol nanocomposite. The films have different nanotube concentrations and thicknesses. For the study, a mode-locked erbium-doped fiber laser in a ring cavity configuration was constructed by setting the films in a microgap between a pair of fiber end facets. With the optimum film among those we have tested, the shortest pulses with a width of $178\mathrm{fs}$ were achieved at $1.56\mathrm{\mu }\mathrm{m}$ with a repetition rate of $22.8\mathrm{MHz}$ and an average power of $1.55\mathrm{mW}$ .